阅读说明：本技术 光功率传输装置 (Optical power transmission device ) 是由 横内则之 渡边健吾 于 2019-08-07 设计创作，主要内容包括：一种光功率传输装置具备：发光单元,其具备第一光增益产生机构和第一光反射机构；光纤；第二光反射机构；以及受光机构,所述光功率传输装置构成为,所述第二光反射机构配置于比所述光纤靠受光机构侧的位置,通过在所述第一光反射机构与所述第二光反射机构之间将所述第一光增益产生机构与所述光纤光学连接而构成第一激光谐振器,在所述第一激光谐振器产生的第一激光向所述受光机构入射。(An optical power transmission device is provided with: a light emitting unit including a first optical gain generating means and a first optical reflecting means; an optical fiber; a second light reflecting mechanism; and a light receiving mechanism, wherein the second optical reflection mechanism is disposed on the light receiving mechanism side of the optical fiber, the first optical gain generation mechanism is optically connected to the optical fiber between the first optical reflection mechanism and the second optical reflection mechanism to form a first laser resonator, and the first laser light generated in the first laser resonator is incident on the light receiving mechanism.)

1. An optical power transmission device, characterized in that,

the optical power transmission device is provided with:

a light emitting unit including a first optical gain generating means and a first optical reflecting means;

an optical fiber;

a second light reflecting mechanism; and

a light receiving mechanism for receiving the light from the light source,

the optical power transmission device is configured such that,

the second light reflection means is disposed on the light receiving means side of the optical fiber,

a first laser resonator is configured by optically connecting the first optical gain generation mechanism and the optical fiber between the first optical reflection mechanism and the second optical reflection mechanism,

the first laser beam generated in the first laser resonator is incident on the light receiving mechanism.

2. The optical power transfer arrangement of claim 1,

the second light reflecting means and the light receiving means are fixed to each other to constitute a light receiving unit.

3. The optical power transfer apparatus of claim 1 or 2,

the optical power transmission device has an energy supply mechanism that supplies energy to the first optical gain generation mechanism.

4. The optical power transmission device according to any one of claims 1 to 3,

the optical fiber is configured to be capable of optical coupling with respect to the second light reflecting means.

5. The optical power transmission device according to any one of claims 2 to 4,

the optical fiber has a first fixing portion on the light receiving unit side,

the light receiving unit has a second fixing portion,

the first fixing portion is detachably connected to a second fixing portion provided at a predetermined position where the optical fiber and the second light reflecting mechanism can be optically connected.

6. The optical power transmission device according to any one of claims 3 to 5,

the energy supply means is set to supply energy of a value in a range that causes the laser oscillation in a state where the first optical reflection means, the optical fiber, and the second optical reflection means are optically connected, and does not cause the laser oscillation in a state where the optical connection is released, to the first optical gain generation means.

7. The optical power transmission device according to any one of claims 1 to 6,

the first optical gain generating mechanism is a semiconductor optical amplifier.

8. The optical power transmission device according to any one of claims 1 to 7,

the light receiving means is a photoelectric conversion element that receives the first laser light output from the first laser resonator and converts the first laser light into a current.

9. The optical power transfer arrangement of claim 8,

the photoelectric conversion element includes a semiconductor material containing silicon (Si) as a main component.

10. The optical power transfer arrangement of claim 8,

the photoelectric conversion element includes a semiconductor material lattice-matched with gallium arsenide (GaAs).

11. The optical power transfer arrangement of claim 8,

the photoelectric conversion element includes a semiconductor material lattice-matched with indium phosphide (InP).

12. The optical power transmission device according to any one of claims 2 to 7,

the light receiving unit includes a second laser resonator and a second optical gain generating mechanism which is disposed in the second laser resonator and generates an optical gain by being supplied with energy,

the second optical gain generating mechanism receives the first laser light to generate optical gain,

laser oscillation is caused by the second laser resonator, and second laser light generated by the laser oscillation is output from the second laser resonator.

13. The optical power transfer arrangement of claim 12,

the second optical gain generating mechanism is composed of an optical material comprising Yttrium Aluminum Garnet (YAG).

14. The optical power transfer arrangement of claim 12,

the second optical gain generating mechanism comprises a semiconductor material lattice matched to gallium arsenide (GaAs).

15. The optical power transfer arrangement of claim 12,

the second optical gain generating mechanism comprises a semiconductor material lattice-matched to indium phosphide (InP).

16. The optical power transmission device according to any one of claims 1 to 7,

the light receiving means is a light emitting means that absorbs the first laser light output from the first laser resonator and emits light having a wavelength different from that of the first laser light.

Technical Field

The present invention relates to an optical power transmission device that transmits optical power through an optical fiber.

Background

As an example of application of optical power transmission using an optical fiber, there is an optical fiber power supply. The optical fiber power supply is a technique of transmitting laser light output from a high-output laser light source to a remote location using an optical fiber, and converting energy of the laser light into electric power by photoelectric conversion in a light receiving unit, thereby driving an electric device using the electric power. Compared with the conventional power supply using copper wires, the optical fiber power supply has many advantages as follows: because the electromagnetic induction is avoided, the noise resistance is strong and no noise is generated; the lightning stroke resistance is high; since it has no electric contact, it can be used even in a high humidity environment; strong explosion-proof performance and the like. Such optical power transmission is also studied as an ignition device in an internal combustion engine of an automobile or the like, for example (non-patent document 1).

On the other hand, when the laser light leaks from the power supply path to the outside and is emitted, there is a possibility that the laser light may damage a human body or a peripheral object. In order to avoid such a possibility, patent document 1 discloses the following structure: the output voltage of the photoelectric conversion mechanism is detected, and when an abnormality is detected, the optical power cut-off mechanism for stopping the laser light source is immediately operated.

Patent document 2 also discloses the following technique: when the light receiving side cannot receive an appropriate signal, the signal light including error information is transmitted from the light receiving side to the light emitting side, and the driving of the laser light source for power supply is stopped in accordance with an instruction from the control unit.

On the other hand, in the optical wireless power feeding technique without using an optical fiber, as disclosed in patent document 3, the following technique is disclosed: a laser resonator is formed between a light emitting unit formed by combining a recursive mirror and a gain mechanism and a light receiving unit formed by combining the recursive mirror and a light receiving mechanism, so that when a shielding object such as a human body is inserted into an optical path of the resonator, laser oscillation is immediately stopped.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2001-37105

Patent document 2: japanese patent laid-open No. 2008 & 193327

Patent document 3: specification of U.S. Pat. No. 9705606

Non-patent document

Non-patent document 1: parallel extension to "possibility of engine ignition with a giant pulse micro laser", j.plasma Fusion res.vol.89, No.4, pp.238, 2013

Disclosure of Invention

Problems to be solved by the invention

However, as in patent documents 1 and 2, in the method of detecting an abnormality on the light receiving side and feeding back the abnormality to the light emitting side in the optical fiber feeding, an abnormality detection mechanism and a circuit for cutting off the operation of the laser light source are additionally required, and the system configuration may become complicated. In addition, this method involves the following problems because of abnormality detection, signal processing, and the like: even in a state where laser oscillation should be stopped originally, it is impossible to eliminate the possibility that laser oscillation is erroneously caused by a malfunction of a mechanism for performing abnormality detection, signal processing, or the like.

In contrast, the optical wireless power feeding system described in patent document 3 ensures high safety. However, when the distance between the light emitting unit and the light receiving unit is far, the power transmission loss increases dramatically, and laser oscillation does not occur. Therefore, a practical power transmission distance is about several meters. Further, when there is an obstacle between the light emitting unit and the light receiving unit, since optical power cannot be transmitted, there is a problem that the installation environment is limited to only a narrow space with a good visual range.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical power transmission device capable of achieving optical power transmission to a place at a long distance and short sight distance while securing high safety with a simple configuration.

Means for solving the problems

In order to solve the above problems and achieve the object, an optical power transmission device according to one aspect of the present invention includes: a light emitting unit including a first optical gain generating means and a first optical reflecting means; an optical fiber; a second light reflecting mechanism; and a light receiving mechanism, wherein the second optical reflection mechanism is disposed on the light receiving mechanism side of the optical fiber, the first optical gain generation mechanism is optically connected to the optical fiber between the first optical reflection mechanism and the second optical reflection mechanism to form a first laser resonator, and the first laser light generated in the first laser resonator is incident on the light receiving mechanism.

In the optical power transmission device according to one aspect of the present invention, the second light reflection means and the light receiving means are fixed to each other to form a light receiving unit.

In the optical power transmission device according to one aspect of the present invention, the optical power transmission device includes an energy supply means for supplying energy to the first optical gain generation means.

In the optical power transmission device according to one aspect of the present invention, the optical fiber is configured to be capable of releasing optical coupling with respect to the second optical reflection mechanism.

In the optical power transmission device according to one aspect of the present invention, the optical fiber has a first fixing portion on the light receiving unit side, and the light receiving unit has a second fixing portion, the first fixing portion being detachably connected to the second fixing portion, and the second fixing portion being provided at a predetermined position where the optical fiber and the second light reflecting mechanism can be optically connected.

In the optical power transmission device according to one aspect of the present invention, the energy supply means is configured to supply energy having a value in a range in which the laser oscillation is caused in a state where the first optical reflection means, the optical fiber, and the second optical reflection means are optically connected, and the laser oscillation is not caused in a case where the optical connection is released, to the first optical gain generation means.

In the optical power transmission device according to one aspect of the present invention, the first optical gain generating means is a semiconductor optical amplifier.

In the optical power transmission device according to one aspect of the present invention, the light receiving means is a photoelectric conversion element that receives the first laser light output from the first laser resonator and converts the first laser light into a current.

In an optical power transmission device according to an aspect of the present invention, the photoelectric conversion element includes a semiconductor material containing silicon (Si) as a main component.

In the optical power transmission device according to one aspect of the present invention, the photoelectric conversion element includes a semiconductor material lattice-matched to gallium arsenide (GaAs).

In an optical power transmission device according to one embodiment of the present invention, the photoelectric conversion element includes a semiconductor material lattice-matched to indium phosphide (InP).

In the optical power transmission device according to one aspect of the present invention, the light receiving unit includes a second laser resonator and a second optical gain generating means that is disposed in the second laser resonator and generates an optical gain by being supplied with energy, and the second optical gain generating means receives the first laser beam to generate an optical gain, causes laser oscillation by the second laser resonator, and outputs a second laser beam generated by the laser oscillation from the second laser resonator.

In the optical power transmission device according to one aspect of the present invention, the second optical gain generating means is made of an optical material including Yttrium Aluminum Garnet (YAG).

In the optical power transmission device according to one aspect of the present invention, the second optical gain generating means includes a semiconductor material lattice-matched to gallium arsenide (GaAs).

In an optical power transmission device according to an aspect of the present invention, the second optical gain generation mechanism includes a semiconductor material lattice-matched to indium phosphide (InP).

In the optical power transmission device according to one aspect of the present invention, the light receiving means is light emitting means for absorbing the first laser light output from the first laser resonator and emitting light having a wavelength different from that of the first laser light.

Effects of the invention

According to the present invention, the following effects are obtained: the optical power transmission to a remote place without the advantage of line-of-sight can be realized while securing high safety with a simple structure.

Drawings

Fig. 1 is a schematic diagram showing a schematic configuration of an optical power transmission device according to a first embodiment.

Fig. 2 is a diagram illustrating a state in which laser oscillation is stopped in the optical power transmission device of fig. 1.

Fig. 3 is a schematic diagram showing a schematic configuration of an optical power transmission device used in a comparative example.

Fig. 4 is a diagram showing an example of the relationship between the drive current and the output current.

Fig. 5 is a diagram showing another example of the relationship between the drive current and the output current.

Fig. 6 is a schematic diagram showing a schematic configuration of an optical power transmission device according to a second embodiment.

Fig. 7 is a schematic diagram showing a schematic configuration of an optical power transmission device according to a third embodiment.

Fig. 8 is a schematic diagram showing a schematic configuration of an optical power transmission device according to a fourth embodiment.

Fig. 9 is a schematic diagram showing a schematic configuration of an optical power transmission device according to a fifth embodiment.

Fig. 10 is a schematic diagram showing a schematic configuration of the headlight unit.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals as appropriate, and overlapping description thereof will be omitted as appropriate. Note that the drawings are schematic, and the dimensional relationship and the like of the respective elements may be different from the actual dimensional relationship and the like. In some cases, the drawings include portions having different dimensional relationships and ratios.

(embodiment I)

Fig. 1 is a schematic diagram showing a schematic configuration of an optical power transmission device according to a first embodiment. The optical power transmission device 100 includes a light emitting unit 10, an optical fiber 20, a light receiving unit 30, and a driving device 40 as an energy supply mechanism.

The light emitting unit 10 includes a semiconductor optical amplifier 11 as a first optical gain generating means, a mirror 12 as a first optical reflecting means, a low reflection film 13, a lens 14, and a housing 15.

The driving device 40 is a known driving device configured to be able to drive the semiconductor optical amplifier 11. The driving device 40 supplies the driving current DC1 to the semiconductor optical amplifier 11 as energy.

In the present embodiment, the semiconductor optical amplifier 11 is an amplifier in which a strained quantum well structure is formed as an active layer on a gallium arsenide (GaAs) substrate. The strained quantum well structure contains a semiconductor material, GaInAs, as a constituent material. The width of the active region including the active layer in the semiconductor optical amplifier 11 is set to a width capable of single-mode waveguide, for example, 2 μm. The semiconductor optical amplifier 11 is a structure obtained by cleaving a wafer into chips having a length of 1mm in the optical waveguide direction and then singulating the chips. The semiconductor optical amplifier 11 emits light by being supplied with the drive current DC1 by the drive device 40, and generates an optical gain. The semiconductor optical amplifier 11 is configured by adjusting the composition of the strained quantum well structure so as to include 980nm as a gain wavelength band.

The reflecting mirror 12 is formed on one cleaved end surface in the optical waveguide direction of the semiconductor optical amplifier 11. The reflecting mirror 12 is, for example, a dielectric multilayer film, and is configured to have a high reflectance of 95% at 980nm included in the gain wavelength band of the semiconductor optical amplifier 11.

The low reflection film 13 is formed on the other cleaved end face in the optical waveguide direction of the semiconductor optical amplifier 11 so as to face the mirror 12 with the semiconductor optical amplifier 11 interposed therebetween. The low reflection film 13 is, for example, a dielectric multilayer film, and has an extremely low reflectance of 0.1% at a wavelength of 980 nm.

The lens 14 is disposed on the opposite side of the low reflection film 13 from the semiconductor optical amplifier 11. The lens 14 optically couples light generated in the semiconductor optical amplifier 11 and output via the low reflection film 13 with one end of the optical fiber 20.

The housing 15 is a housing for accommodating the semiconductor optical amplifier 11, the mirror 12, the low reflection film 13, and the lens 14, and is made of, for example, a metal material. One end of the optical fiber 20 is connected to the frame 15.

The optical fiber 20 connects the light emitting unit 10 and the light receiving unit 30, and is a Single Mode Fiber (SMF) in the present embodiment. One end of the optical fiber 20 connected to the frame 15 is processed into a lens shape, and is optically connected to the semiconductor optical amplifier 11 via the lens 14 on the end surface side where the low reflection film 13 is formed, as described above. A connector 21 is provided at the other end of the optical fiber 20, and the connector 21 is connected to the light receiving unit 30. The connector 21 is constituted by a known ferrule or optical connector. The other end of the optical fiber 20, at which the connector 21 is provided, is polished so that the reflection attenuation is 30dB or more (i.e., the reflectance is 0.1% or less). The connector 21 corresponds to a first fixing portion of the optical fiber 20 on the light receiving unit 30 side.

The light receiving unit 30 includes a housing 31, a mirror 32 as a second light reflecting means, and a light receiving module 33.

The housing 31 is a housing that houses the reflecting mirror 32 and the light receiving module 33, and is made of, for example, a metal material. The housing 31 is provided with a connector connecting portion 31a to which the connector 21 can be connected. By connecting the connector 21 to the connector connecting portion 31a, the optical fiber 20 is connected to the light receiving unit 30. The connector 21 may be detachably connected to the connector connecting portion 31a, or may be bonded to the connector connecting portion 31 a.

The reflecting mirror 32 is disposed in the vicinity of the connector connecting portion 31 a. Specifically, the reflecting mirror 32 is disposed such that its reflecting surface faces the other end of the optical fiber 20 at a short distance, for example, a short distance of a degree of almost contact, in a state where the connector 21 is connected to the connector connection portion 31 a. The optical fiber 20 is thereby optically connected to the mirror 32. Therefore, the connector connecting portion 31a corresponds to a second fixing portion provided at a predetermined position (the light receiving unit 30 in the present embodiment) where the optical fiber 20 and the reflecting mirror 32 can be optically connected. The connector 21 as the first fixing portion is connected to the connector connecting portion 31a as the second fixing portion. The reflecting mirror 32 is, for example, an optical plate (e.g., a glass plate) formed with a dielectric multilayer film, and is configured to transmit most of light at a wavelength of 980nm and have a reflectance of 5%.

The light receiving module 33 includes a light receiving element 33a and an output terminal 33 b. The light receiving element 33a is a photoelectric conversion element, for example, a photodiode, which converts received light into a current of an amount corresponding to the received light power and outputs the current. Preferably, a low reflection film is formed on the light receiving surface of the light receiving element 33 a. The output terminal 33b is a terminal electrically connected to the light receiving element 33a and used for extracting current. In the present embodiment, the light receiving element 33a is an element including a semiconductor material containing silicon (Si) as a main component, for example, an element including Si. The semiconductor material containing Si as a main component means a semiconductor material in which the composition ratio of Si is higher than 50%, and for example, a semiconductor material in which the composition ratio of Si is 99% or more and the composition ratio of other impurities is 1% or less. Si has high light receiving sensitivity to light having a wavelength of around 1000nm such as 980nm and is inexpensive.

Here, the mirror 12, the optical fiber 20, and the mirror 32 are optically connected in this order, and thereby a laser resonator LC1 as a first laser resonator is configured at a wavelength of 980 nm. The semiconductor optical amplifier 11 is disposed in the laser resonator LC 1.

The operation of the optical power transmission device 100 will be described. First, the driving device 40 supplies the driving current DC1 to the semiconductor optical amplifier 11. Then, the semiconductor optical amplifier 11 emits light of a wavelength within its gain band, and generates an optical gain. Then, in a state where the semiconductor optical amplifier 11 generates an optical gain, laser oscillation is caused by the laser resonator LC1, and the laser light L1 as the first laser light generated by the laser oscillation is output from the laser resonator LC1 in the light receiving unit 30. Specifically, the laser light L1 is output from the mirror 32 constituting one end of the laser resonator LC1 in the light receiving unit 30. That is, the optical power transmission device 100 is configured such that the laser light L1 generated in the laser resonator LC1 is output from the laser resonator LC1 in the light receiving unit 30. As a result, high optical power generated by laser oscillation is transmitted as laser light L1 from the light emitting unit 10 to the light receiving unit 30 via the optical fiber 20. In the light receiving module 33, the light receiving element 33a receives the laser light L1 and performs photoelectric conversion, and the converted current is output from the output terminal 33 b.

On the other hand, as shown in fig. 2, when the connector 21 is detached from the connector connection portion 31a, the optical connection of the mirror 12, the optical fiber 20, and the mirror 32 is released. In this case, the laser resonator LC1 is not configured. As a result, the low-power light L2 not subjected to laser oscillation is output from the connector 21 side of the optical fiber 20 without causing laser oscillation.

In this way, in the optical power transmission device 100, high optical power is transmitted in a state where laser oscillation by the laser resonator LC1 is caused, and light L2 having low power is output without causing laser oscillation in a state where the laser resonator LC1 is not configured. Therefore, according to the optical power transmission device 100, when an abnormality such as a drop of the connector 21 of the optical fiber 20 connecting the light emitting unit 10 and the light receiving unit 30 occurs, the laser oscillation is automatically stopped. Thus, the laser beam can be prevented from leaking to the outside with a simple structure and high safety can be ensured without providing an abnormality detection mechanism for the light receiving unit and a cutting mechanism for the light emitting unit. Further, since the optical fiber 20 is used, it is possible to safely perform power feeding and power transmission to a remote place or a place short of sight distance, which cannot be achieved in optical wireless power feeding.

(examples and comparative examples)

As an example, an optical power transmission device having the same configuration as the optical power transmission device 100 according to the first embodiment was manufactured, and a drive current was supplied to a semiconductor optical amplifier to measure the characteristics thereof. As a comparative example, an optical power transmission device having the same configuration as the optical power transmission device 200 shown in fig. 3 was prepared, and a drive current was supplied to the semiconductor optical amplifier to measure the characteristics thereof. In the optical power transmission device 200, the light receiving unit 30 of the optical power transmission device 100 is replaced with a light receiving unit 230 configured by removing the reflecting mirror 32 from the light receiving unit 30.

Fig. 4 is a diagram illustrating an example of a relationship between the driving current and the output current of the light receiving unit. In fig. 4, the horizontal axis represents the drive current supplied to the semiconductor optical amplifier, and the vertical axis represents the output current output from the light receiving module in the light receiving unit. In an embodiment, as shown by line L11, if the current I1 (about 50mA) is exceeded, laser oscillation is caused and an output current is generated. When the driving current is about 500mA, the light receiving unit outputs about 200mA, that is, when the voltage is 0.75V, the light receiving unit obtains about 150mW of electric power.

On the other hand, in the comparative example, as shown by a line L12, it was confirmed that when the drive current was about 500mA, no laser oscillation occurred and no output current was generated. This is considered to indicate that when the laser resonator is not configured, such as when the optical fiber connector is disconnected when the drive current is about 500mA, the laser oscillation is automatically stopped and does not leak to the outside.

When the current I2 (about 650mA) was exceeded, laser oscillation was also caused in the case of the comparative example. Therefore, in order to ensure safety more reliably, it is preferable that the drive device be set to control the drive current so as to supply a current having a value in a range in which laser oscillation is caused in a state in which the laser resonator is configured by performing a predetermined optical connection, and in which laser oscillation is not caused in a state in which the laser resonator is not configured by releasing the predetermined optical connection.

Next, fig. 5 is a diagram showing another example of the relationship between the drive current and the output current. Lines L21 and L22 show the relationship with respect to the optical power transmission device in which the length of the semiconductor optical amplifier in the optical waveguide direction was 1mm, and the length of the semiconductor optical amplifier was replaced with a 3mm chip, for the optical power transmission devices of the above-described examples and comparative examples. As shown in fig. 5, when the length of the semiconductor optical amplifier is 3mm, there is no large difference in the relationship between the drive current and the output current in any case. That is, the output current starts to increase in a state where the drive current is 100mA or less, and an output current of about 200mA is obtained in a state where the drive current is 500 mA.

The reason for this is considered to be that since the gain is high even if the semiconductor optical amplifier is long, even if reflection is not performed by the mirror in the light receiving unit, laser oscillation is caused by the influence of reflection (for example, reflectance of 0.1%) at the low reflection film of the semiconductor optical amplifier, for example. Therefore, it is necessary to appropriately set a drive current and a gain of the semiconductor optical amplifier, for example, and to cause laser oscillation by the first laser resonator. In addition, the optical fiber has a transmission loss with respect to the wavelength, which is, for example, about 3dB/km at a wavelength of 980 nm. Therefore, when an optical fiber having a length in which the transmission loss cannot be ignored is used, the conditions necessary for laser oscillation, for example, the reflectance of the mirror in the light receiving unit, becomes higher. Thus, the reflectance is appropriate depending on the length of the optical fiber. It is more preferable that, regarding these various parameters that affect the laser oscillation by the first laser resonator, appropriate settings are made in accordance with the transmission distance, the required power output on the light receiving unit side, the allowable power consumption on the light emitting unit side, and the like, so as to cause the laser oscillation by the first laser resonator.

In the above embodiment, the reflecting mirror 32 as the second light reflecting means is an optical plate on which a dielectric multilayer film is formed, but the second light reflecting means is not limited to this, and may be realized by a dielectric multilayer film formed on the light receiving surface of the light receiving element 33 a.

(second embodiment)

Fig. 6 is a schematic diagram showing a schematic configuration of an optical power transmission device according to a second embodiment. The optical power transmission device 100A has a configuration in which the light receiving unit 30 is replaced with a light receiving unit 30A in addition to the configuration of the optical power transmission device 100 shown in fig. 1.

The light receiving unit 30A has a structure in which the reflection mirror 32 is replaced with a connector 34 and a Fiber Bragg Grating (FBG) 35 in addition to the structure of the light receiving unit 30 of the optical power transmission device 100.

The connector 34 is provided at one end of the FBG 35. The connector 34 is formed of a known ferrule or an optical connector, and is connected to the connector connection portion 31a of the housing 31 so as to face the connector 21. Thereby, the FBG 35 is optically connected to the optical fiber 20. The connector 34 may be detachably connected to the connector connecting portion 31a, or may be bonded to the connector connecting portion 31 a. The end of the FBG 35 where the connector 34 is provided is polished so that the reflection attenuation amount is 30dB or more.

The FBG 35 is an SMF having a core 35a and a cladding 35b, and a grating G having a periodic refractive index distribution is formed on the core 35 a. The grating G is configured to bragg reflect a specific wavelength, and in the present embodiment, is configured to transmit most of light at a wavelength of 980nm and has a reflectance of 5%. The FBG 35 functions as a second light reflection mechanism. The other end of the FBG 35 faces the light receiving surface of the light receiving element 33a of the light receiving module 33, and the FBG 35 is optically connected to the light receiving element 33 a.

In the optical power transmission device 100A, the mirror 12, the optical fiber 20, and the FBG 35 of the light emitting unit 10 are optically connected in this order, thereby constituting a laser resonator LC2 as a first laser resonator at a wavelength of 980 nm. The semiconductor optical amplifier 11 is disposed in the laser resonator LC 2.

The optical power transmission device 100A operates in the same manner as the optical power transmission device 100. That is, first, the driving device 40 supplies the driving current DC1 to the semiconductor optical amplifier 11. In a state where the semiconductor optical amplifier 11 generates an optical gain, laser oscillation is caused by the laser resonator LC2, and laser light L1 generated by the laser oscillation is output from the FBG 35 of the laser resonator LC2 in the light receiving unit 30A. As a result, high optical power generated by laser oscillation is transmitted as laser light L1 from the light emitting unit 10 to the light receiving unit 30 via the optical fiber 20. In the light receiving module 33, the light receiving element 33a receives the laser light L1 and performs photoelectric conversion, and the converted current is output from the output terminal 33 b. On the other hand, when the connector 21 or the connector 34 is detached from the connector connection portion 31a, the laser resonator LC2 is not configured, so that laser oscillation is not caused.

Therefore, in the optical power transmission device 100A, similarly to the optical power transmission device 100, it is possible to prevent the laser light from leaking to the outside with a simple configuration, to secure high safety, and to safely supply power and transmit power to a remote place or a place short of sight distance.

(third embodiment)

Fig. 7 is a schematic diagram showing a schematic configuration of an optical power transmission device according to a third embodiment. The optical power transmission device 100B has a structure in which the light emitting unit 10 is replaced with the light emitting unit 10B, the optical fiber 20 is replaced with the optical fiber 20B, and the light receiving unit 30 is replaced with the light receiving unit 30B, in addition to the structure of the optical power transmission device 100 shown in fig. 1.

The light emitting unit 10B has a structure in which the semiconductor optical amplifier 11 is replaced with a semiconductor optical amplifier 11B in addition to the structure of the light emitting unit 10. The semiconductor optical amplifier 11B has the same material and structure as those of the semiconductor optical amplifier 11, but the width of the active region is set to a width capable of multi-mode waveguide, for example, 100 μm.

The optical fiber 20B is a multimode fiber (MMF) having a core diameter of, for example, 100 μm.

The light receiving unit 30B has a structure in which the mirror 32 is replaced with a Volume Bragg Grating (VBG) 32B in addition to the structure of the light receiving unit 30 of the optical power transmission device 100.

VBG 32B is a large-area diffraction grating plate, and is configured to transmit most of light at a wavelength of 980nm and have a reflectance of 5%. The VBG 32B functions as a second light reflection mechanism. VBG 32B is provided on, for example, an inner wall of housing 31, faces a light receiving surface of light receiving element 33a at a predetermined distance, and VBG 32B is optically connected to light receiving element 33 a.

In the optical power transmission device 100B, the mirror 12, the optical fiber 20B, and the VBG 32B of the light emitting unit 10B are optically connected in this order, and thereby a laser resonator LC3 as a first laser resonator is configured at a wavelength of 980 nm. The semiconductor optical amplifier 11B is disposed in the laser resonator LC 3.

The optical power transmission device 100B operates in the same manner as the optical power transmission device 100. That is, the semiconductor optical amplifier 11B generates laser oscillation by the laser resonator LC3 in a state where the drive current DC1 is supplied from the drive device 40 to generate an optical gain, and the laser light L3 generated by the laser oscillation is output from the VBG 32B. As a result, high optical power generated by laser oscillation is transmitted as laser light L3 from the light emitting unit 10B to the light receiving unit 30B via the optical fiber 20B.

In particular, in the optical power transmission device 100B, since the width of the active region of the semiconductor optical amplifier 11B is set to a width capable of multimode waveguide and the optical fiber 20B is MMF, extremely high optical power exceeding 1W, for example, is transmitted as the laser light L3.

In the light receiving module 33B, the light receiving element 33a receives the laser light L1, performs photoelectric conversion, and outputs the converted current from the output terminal 33B. On the other hand, when the connector 21 is detached from the connector connection portion 31a, the laser resonator LC3 is not configured, so that laser oscillation is not caused.

In the optical power transmission device 100B, the VBG 32B is spaced a predetermined distance from the light receiving surface of the light receiving element 33a, and therefore the beam diameter of the laser light L3 on the light receiving surface can be sufficiently increased compared to the core diameter of the optical fiber 20B. As a result, the power density of light on the light receiving surface can be reduced, and thus damage to the light receiving surface of the light receiving element 33a can be avoided. Preferably, the distance between VBG 32B and the light receiving surface of light receiving element 33a is appropriately set based on the resistance to the optical power density of light receiving element 33a and the power of laser light L3.

In addition, when the optical fiber 20B is MMF, it is generally difficult to form a grating in a core, and therefore it is effective to use VBG 32B.

In the optical power transmission device 100B, similarly to the optical power transmission device 100, it is possible to prevent laser light from leaking to the outside with a simple configuration, to secure high safety, and to safely supply power and transmit power to a remote place or a place short of sight distance.

In the above embodiment, the photoelectric conversion element includes a semiconductor material containing Si as a main component. However, the structural material of the photoelectric conversion element is not limited thereto, and may be appropriately selected according to the wavelength of received light, or the like.

For example, the photoelectric conversion element may also include a semiconductor material lattice-matched to gallium arsenide (GaAs). Here, the lattice matching includes both unstrained lattice matching and strained lattice matching. Examples of the semiconductor material lattice-matched to GaAs include GaAs and AlGaAs. As the structure of the photoelectric conversion element, a structure in which a GaAs layer or an AlGaAs layer is formed as an absorption layer on a GaAs substrate can be used. In the case of a photoelectric conversion element including a semiconductor material lattice-matched to GaAs, photoelectric conversion efficiency for light having a wavelength of around 1000nm, such as 980nm, can be improved.

In addition, the photoelectric conversion element may include a semiconductor material lattice-matched with indium phosphide (InP). As a semiconductor material lattice-matched to InP, GaInAsP, AlGaInAs, and the like are available. As the structure of the photoelectric conversion element, a structure in which a GaInAsP layer and an AlGaInAs layer are formed as an absorption layer on an InP substrate can be used. In the case of a photoelectric conversion element including a semiconductor material lattice-matched to InP, photoelectric conversion efficiency for light having a wavelength around 1550nm, which is one of communication bands, can be improved.

(fourth embodiment)

As a fourth embodiment, an optical power transmission device that directly utilizes light without converting optical power transmitted through an optical fiber into electric power will be described. Fig. 8 is a schematic diagram showing a schematic configuration of an optical power transmission device according to a fourth embodiment. The optical power transmission device 100C has a configuration in which the light emitting unit 10B is replaced with the light emitting unit 10C and the light receiving unit 30B is replaced with the light receiving unit 30C, in addition to the configuration of the optical power transmission device 100B shown in fig. 7.

The light emitting unit 10C has a structure in which the semiconductor optical amplifier 11B is replaced with a semiconductor optical amplifier 11C, the reflecting mirror 12 is replaced with a reflecting mirror 12C, and the low reflection film 13 is replaced with a low reflection film 13C in addition to the structure of the light emitting unit 10B.

The semiconductor optical amplifier 11C has the same material and structure as those of the semiconductor optical amplifier 11B, but the composition and structure of the material are adjusted so as to include 808nm as a gain wavelength band. The reflecting mirror 12C is, for example, a dielectric multilayer film, and is configured to have a high reflectance of 95% at 808nm included in the gain wavelength band of the semiconductor optical amplifier 11. The low reflection film 13C is, for example, a dielectric multilayer film, and has an extremely low reflectance of 0.1% at a wavelength of 808 nm.

The light receiving unit 30C includes a housing 31C, VBG32C, lenses 36a and 36b, a microchip 37 as a second optical gain generating means, reflective films 38a and 38b, and an output window 39.

The housing 31C is a cylindrical housing that houses the VBG32C, the lenses 36a and 36b, the microchip 37, the reflective films 38a and 38b, and the output window 39, and is made of, for example, a metal material. A connector connecting portion 31Ca that can be connected to the connector 21 is provided at one end of the housing 31C.

The VBG32C is configured to transmit most of light at a wavelength of 808nm and has a reflectance of 5%. The VBG32C is opposed to the end of the optical fiber 20B where the connector 21 is provided.

The mirror 12C, the optical fiber 20B, and the VBG32C of the light emitting unit 10C are optically connected in this order, thereby constituting a laser resonator LC4 as a first laser resonator at a wavelength of 808 nm. The semiconductor optical amplifier 11C is disposed in the laser resonator LC 4. The semiconductor optical amplifier 11C causes laser oscillation by the laser resonator LC4 in a state where the drive current DC1 is supplied from the drive device 40 to generate an optical gain, and laser light L4 generated by the laser oscillation is output from the VBG 32C. As a result, high optical power generated by laser oscillation is transmitted as laser light L4 from the light emitting unit 10C to the light receiving unit 30C via the optical fiber 20B.

The lens 36a is disposed to face the VBG 32C. Lens 36a functions as an optical system for inputting laser light L4 to microchip 37.

The microchip 37 is made of an optical material containing Yttrium Aluminum Garnet (YAG), and in the present embodiment, is made of YAG.

The reflective films 38a and 38b are provided on the end surfaces thereof facing the microchip 37, respectively, and are, for example, dielectric multilayer films. The reflective film 38a transmits almost all of the laser light L4 having a wavelength of 808nm and reflects light having a wavelength of 1064nm at a high reflectance (e.g., 95% or more). The reflective film 38b is configured to transmit most of the light at a wavelength of 1064nm and has a reflectance of 50%.

The reflective films 38a and 38b constitute a laser resonator LC5 serving as a second laser resonator that functions at a wavelength of 1064 nm. The microchip 37 is disposed inside the laser resonator LC 5. The microchip 37 receives the laser light L4 transmitted through the reflective film 38a as excitation light, and emits light having a wavelength of 1064nm, thereby generating an optical gain. Then, laser oscillation is caused by the laser resonator LC5, and the laser light L5 having a wavelength of 1064nm as the second laser light generated by the laser oscillation is output from the reflection film 38b side of the laser resonator LC 5. That is, the reflective films 38a and 38b and the microchip 37 function as a YAG laser unit.

The lens 36b is disposed so as to face the reflective film 38b, and functions as a condensing optical system that condenses the laser light L5. The output window 39 is an optical window disposed on the other end side of the housing 31C so as to face the lens 36b, and transmits the laser light L5 to be output to the outside.

As described above, in the optical power transmission device 100C, the laser resonator LC4 constitutes an excitation laser light generating section with respect to the YAG laser section. In the optical power transmission device 100C, similarly to the optical power transmission device 100, it is possible to prevent the laser light L4 from leaking to the outside with a simple configuration, to secure high safety, and to safely supply power and transmit power to a remote place or a place short of sight distance.

The optical power transmission device 100C can be suitably used as an ignition device in an internal combustion engine, for example. Since the YAG laser can generate pulse laser light having extremely high peak power by pulse excitation, high combustion efficiency can be achieved in the internal combustion engine. In the optical power transmission device 100C, as a method of making the laser beams L4 and L5 pulse laser beams, for example, a method of making the drive current DC1 supplied from the drive device 40 to the semiconductor optical amplifier 11C a pulse current is given. When the optical power transmission device 100C is used as an ignition device, for example, when the connector 21 is loosened, or when the light receiving unit 30C corresponding to the replacement of the spark plug is replaced, the output of the laser light L4 and L5 is automatically stopped, so that safety is ensured.

In the internal combustion engine, a space in which the light emitting unit 10C can be provided in the vicinity thereof may not be secured. In the optical power transmission device 100C, the light emitting unit 10C is preferably disposed at a mountable position, and the optical power can be transmitted from there to the light receiving unit 30C provided in the internal combustion engine through the optical fiber 20B.

In the above-described embodiment, the microchip 37 as the second optical gain generation means is made of YAG, but the material constituting the second optical gain generation means is not limited to this, and may be YVO (yttrium vanadium oxide) or the like, and may be appropriately selected according to a desired laser oscillation wavelength or the like.

For example, the second optical gain generating mechanism may also comprise a semiconductor material lattice-matched to GaAs. Examples of the semiconductor material lattice-matched to GaAs include GaAs, AlGaAs, InGaAs, and AlInGaP. As the structure of the second optical gain generation means, a structure in which a GaAs layer, an AlGaAs layer, an InGaAs layer, an AlInGaP layer, or the like is formed as a light emitting layer on a GaAs substrate can be used. In the second optical gain generating means including a semiconductor material lattice-matched to GaAs, the laser oscillator is suitable for laser oscillation at a wavelength of around 1000nm, such as 980 nm.

In addition, the second optical gain generating mechanism may also comprise a semiconductor material lattice-matched to InP. As a semiconductor material lattice-matched to InP, GaInAsP, AlGaInAs, and the like are available. As the structure of the second optical gain generation means, a structure in which a GaInAsP layer and an AlGaInAs layer are formed as a light-emitting layer on an InP substrate can be used. The photoelectric conversion element including the second optical gain generation means lattice-matched to InP is suitable for laser oscillation at a wavelength around 1550nm, which is one of the communication bands.

(fifth embodiment)

As a fifth embodiment, an optical power transmission device that directly utilizes light without converting optical power transmitted through an optical fiber into electric power will be described. Fig. 9 is a schematic diagram showing a schematic configuration of an optical power transmission device according to a fifth embodiment. The optical power transmission device 100D has a configuration in which the light emitting unit 10 is replaced with the light emitting unit 10D, the light receiving unit 30 is replaced with the light receiving unit 30D, and the headlight unit 50 is added in addition to the configuration of the optical power transmission device 100 shown in fig. 1. The optical power transmission device 100D is suitable for a laser headlamp of a motor vehicle. The laser headlamp has advantages that the spot size of light can be reduced, high-luminance illumination can be performed, and bright illumination can be performed to a distance of several hundred meters.

The light emitting unit 10D has a structure in which the semiconductor optical amplifier 11 is replaced with a semiconductor optical amplifier 11D, the reflecting mirror 12 is replaced with a reflecting mirror 12D, and the low reflection film 13 is replaced with a low reflection film 13D in addition to the structure of the light emitting unit 10.

The semiconductor optical amplifier 11D adjusts the composition and structure of the material so as to include 400nm, which is a blue wavelength (360nm to 480nm), as a gain wavelength band. The reflecting mirror 12D is, for example, a dielectric multilayer film, and is configured to have a high reflectance of 95% at a wavelength of 400 nm. The low reflection film 13D is, for example, a dielectric multilayer film, and is configured to have an extremely low reflectance of 0.1% at a wavelength of 400 nm.

The light emitting unit 10 is mounted on a member having high heat dissipation performance in an automobile, and in the present embodiment, is mounted on a frame F of a vehicle body.

The light receiving unit 30D includes a housing 31D and a mirror 32D as a second light reflecting means housed in the housing 31D. The optical fiber 20 is inserted into the housing 31D, and the optical fiber 20 is fixed to the housing 31D so that one end thereof is close to and faces the mirror 32D. Whereby the optical fiber 20 is optically connected to the mirror 32D. The reflecting mirror 32D is, for example, an optical plate (such as a glass plate) formed with a dielectric multilayer film, and is configured to transmit most of light at a wavelength of 400nm and have a reflectance of 5%, similarly to the reflecting mirror 32 shown in fig. 1.

The mirror 12D, the optical fiber 20, and the mirror 32D of the light emitting unit 10D are optically connected in this order, thereby constituting a laser resonator LC6 as a first laser resonator at a wavelength of 400 nm. The semiconductor optical amplifier 11D is disposed in the laser resonator LC 6. In the semiconductor optical amplifier 11D, in a state where the drive current DC1 is supplied from the drive device 40 to generate an optical gain, laser oscillation is caused by the laser resonator LC6, and the laser light L6 generated by the laser oscillation is output from the mirror 32D. As a result, high optical power generated by laser oscillation is transmitted from the light emitting unit 10D to the light receiving unit 30D as the first laser light, i.e., the laser light L6, through the optical fiber 20.

The headlight unit 50 includes a housing 51, a reflector 52, a light emitting unit 53, a reflector 54, and a projection lens 55. The housing 51 is made of, for example, resin, houses the reflecting mirror 52, the light emitting section 53, and the reflecting mirror 54, and is attached so that the projection lens 55 is exposed to the outside. Further, the light receiving unit 30D is mounted on the housing 51.

The reflecting mirror 52 reflects the laser light L6 output from the light receiving unit 30D toward the light emitting unit 53. The light emitting section 53 is made of a resin containing a known fluorescent material that absorbs blue light and emits yellow light as a complementary color thereof. Therefore, the light emitting unit 53 absorbs a part of the laser light L6 and emits yellow light having a wavelength different from that of the laser light L6. Thereby, the light emitting unit 53 outputs white light L7. The reflecting mirror 54 is not a concave mirror, and condenses the white light L7 and reflects it toward the projection lens 55. The projector lens 55 condenses the white light L7 and outputs the condensed light to the outside. The structure of the light emitting unit 53 is an example, and is not limited to this.

In the optical power transmission device 100D, similarly to the optical power transmission device 100, leakage of the laser light L6 to the outside can be prevented with a simple configuration, and high safety can be ensured. In addition, in the automobile, a space in which the light emitting unit 10D can be disposed near the headlight unit 50 may not be secured. In the optical power transmission device 100D, the light emitting unit 10D is preferably disposed at an installable position, and the optical power can be transmitted from there to the light receiving unit 30D provided in the headlight unit 50 through the optical fiber 20.

The optical power transmission device 100D is also a preferable configuration in terms of thermal countermeasure.

For example, fig. 10 is a schematic diagram showing a schematic configuration of a headlight unit incorporating a blue laser light source. The headlamp unit 350 accommodates a blue laser light source 310 in a housing 351. The blue laser light source 310 receives a current from a terminal 311 and outputs blue laser light L31. The reflecting mirror 352 reflects the laser beam L31 output from the blue laser light source 310 toward the light emitting unit 353. The light emitting unit 353 absorbs a part of the laser light L31 to emit yellow light, which is a complementary color thereof, and thereby outputs white light L32. The reflecting mirror 354 is a concave mirror, and condenses the white light L32 and reflects the condensed light toward the projection lens 355. The projection lens 355 condenses the white light L32 and outputs the condensed light to the outside.

In the headlamp unit 350, the blue laser light source 310 having high luminance is assembled in the highly hermetically sealed housing 351, and there is a problem in heat dissipation of heat generated by the blue laser light source 310. In contrast, in the optical power transmission device 100D, the light emitting unit 10D is disposed in close contact with a member having high heat dissipation, such as the frame F, and transmits the optical power to the vicinity of the light emitting portion 53 of the headlamp unit 50 with the laser light L6 through the optical fiber 20. In addition, when the optical fiber 20 is detached, the laser oscillation is stopped. As a result, a safe laser head lamp system having excellent heat dissipation properties can be realized.

In the above-described embodiment, the first optical gain generating means is a semiconductor optical amplifier, but may be another optical gain generating means used in a solid-state laser such as a YAG rod. In this case, the energy supply means is, for example, a laser light source, and supplies energy for generating a gain to the YAG rod by light.

The present invention is not limited to the above embodiments. The present invention also encompasses a configuration in which the constituent elements of the above embodiments are appropriately combined. Further, those skilled in the art can easily derive further effects and modifications. Therefore, the broader aspects of the present invention are not limited to the above embodiments, and various modifications are possible.

Industrial applicability

As described above, the present invention is suitably applied to optical power transmission using an optical fiber.

Description of reference numerals:

10. 10B, 10C, 10D light emitting unit

11. 11B, 11C, 11D semiconductor optical amplifier

12. 12C, 12D, 32D, 52, 54 mirror

13. 13C, 13D Low reflection film

14. 36a, 36b lens

15. 31, 31C, 31D, 51 frame

20. 20B optical fiber

21. 34 connector

30. 30A, 30B, 30C, 30D light receiving unit

31a, 31Ca connector connecting part

32B VBG

33. 33B light receiving module

33a light receiving element

33b output terminal

35 FBG

35a iron core

35b cladding

37 microchip

38a, 38b reflective film

39 output window

40 drive device

50 head lamp unit

53 light emitting part

55 projection lens

100. 100A, 100B, 100C, 100D optical power transmission device

DC1 drive current

F frame

G grating

L1, L3, L4, L5 and L6 lasers

L2 light

L7 white light

LC1, LC2, LC3, LC4, LC5 and LC6 laser resonators.