阅读说明：本技术 可调谐激光器 (Tunable laser ) 是由 许克畇 陆龙钊 张大鹏 贾楠 卢建南 于 2020-06-17 设计创作，主要内容包括：本发明提供一种可调谐激光器,包括放大装置和FP光滤波装置,放大装置设置有放大输出端、信号输出端和信号输入端,FP光滤波装置设置有滤波输入端和滤波输出端,滤波输入端与放大输出端通过第一光纤连接,滤波输出端与信号输入端通过第二光纤连接,放大装置还设置有第一放大光路、输出光路、透反件和第一半导体光放大器,信号输入端、第一半导体光放大器和放大输出端沿第一放大光路布置,透反件设置在第一放大光路上,透反件位于第一半导体光放大器的前级或后级,透反件和信号输出端沿输出光路布置。放大装置、第一光纤、FP光滤波装置和第二光纤构成封闭的环形腔,将必要器件集成化布置,既可以缩短环形腔的长度,也可以保证整个环形腔的稳定性。(The invention provides a tunable laser, which comprises an amplifying device and an FP optical filter device, wherein the amplifying device is provided with an amplifying output end, a signal output end and a signal input end, the FP optical filter device is provided with a filter input end and a filter output end, the filter input end is connected with the amplifying output end through a first optical fiber, the filter output end is connected with the signal input end through a second optical fiber, the amplifying device is also provided with a first amplifying light path, an output light path, a transflective piece and a first semiconductor optical amplifier, the signal input end, the first semiconductor optical amplifier and the amplifying output end are arranged along the first amplifying light path, the transflective piece is arranged on the first amplifying light path, the transflective piece is positioned at the front stage or the rear stage of the first semiconductor optical amplifier, and the transflective piece and the signal output end are arranged along the output. The amplifying device, the first optical fiber, the FP optical filter device and the second optical fiber form a closed annular cavity, necessary devices are integrally arranged, the length of the annular cavity can be shortened, and the stability of the whole annular cavity can be guaranteed.)

1. The tunable laser is characterized by comprising an amplifying device and an FP optical filter device, wherein the amplifying device is provided with an amplifying output end, a signal output end and a signal input end, the FP optical filter device is provided with a filter input end and a filter output end, the filter input end is connected with the amplifying output end through a first optical fiber, and the filter output end is connected with the signal input end through a second optical fiber;

amplifying device still is provided with first enlarged light path, output light path, passes through anti-piece and first semiconductor optical amplifier, signal input part first semiconductor optical amplifier with enlarge the output and follow first enlarged light path arranges, it is in to pass through anti-piece setting first enlarged light path, it is located to pass through anti-piece preceding stage or the back stage of first semiconductor optical amplifier, pass through anti-piece with signal output part follows output light path arranges.

2. The tunable laser of claim 1, wherein:

the amplifying device is also provided with a first reflecting piece, the first reflecting piece is arranged on the output light path, the first reflecting piece is positioned between the signal output end and the transflective piece, and the signal output end and the amplifying output end or the signal input end are positioned on the same side.

3. The tunable laser of claim 2, wherein:

the first reflector is located on a reflective side of the transflective member.

4. The tunable laser of claim 1, wherein:

the amplifying device is further provided with a second semiconductor optical amplifier, the second semiconductor optical amplifier is arranged on the output light path, and the second semiconductor optical amplifier is located between the amplifying output end and the first transmission and reflection piece.

5. The tunable laser of claim 1, wherein:

the amplifying device further comprises a first optical fiber base and a second optical fiber base, wherein the output end of the first optical fiber is arranged on the first optical fiber base, and the input end of the second optical fiber base is arranged on the second optical fiber base.

6. A tuneable laser according to anyone of claims 1 to 5, characterised in that:

amplifying device is still being located on the first enlarged light path first semiconductor light amplifier's both ends set up first optical isolator and second optical isolator, first optical isolator is located first semiconductor light amplifier's front end, second optical isolator is located first semiconductor light amplifier's rear end.

7. The tunable laser of claim 6, wherein:

the first optical isolator is an optical isolator having a collimating lens, and the second optical isolator is an optical isolator having a focusing lens and a collimating lens.

8. A tuneable laser according to anyone of claims 1 to 5, characterised in that:

the first optical fiber and/or the second optical fiber adopt single mode optical fibers or polarization maintaining optical fibers.

9. A tuneable laser according to anyone of claims 1 to 5, characterised in that:

the amplifying device is further provided with a bearing base and a semiconductor refrigerator, the bearing base is arranged on a first heat conduction end of the semiconductor refrigerator, and the first semiconductor optical amplifier is arranged on the bearing base.

10. The tunable laser of claim 9, wherein:

the amplifying device further comprises a packaging shell, a closed containing cavity is enclosed by the packaging shell, the transflective piece, the first semiconductor optical amplifier, the bearing base and the semiconductor refrigerator are arranged in the containing cavity, and a second heat conduction end of the semiconductor refrigerator is connected with the packaging shell.

Technical Field

The invention relates to the field of optical devices, in particular to a tunable laser.

Background

Single-frequency tunable lasers and high-speed wavelength swept lasers are widely used in many fields, such as Optical Coherence Tomography (OCT), biochemical spectroscopy, fiber sensing applications, and optical communications, and compact and stable tunable laser sources are of paramount importance for achieving a wide range of commercial applications.

In practical use, all devices of the ring cavity, including a semiconductor optical amplifier, an optical isolator, a coupler, an optical filter and the like, are generally connected in an optical fiber fusion mode, so that a short ring cavity is difficult to manufacture and is a basis for realizing discrete single-frequency tuning and rapid frequency sweeping. In addition, in the case of a long cavity length, the connection of a plurality of devices leads to a complicated laser layout structure, which is not favorable for the design trend of miniaturization.

Disclosure of Invention

The invention aims to provide a tunable laser with integrated arrangement and short cavity length.

In order to achieve the purpose of the invention, the invention provides a tunable laser, which comprises an amplifying device and an FP optical filter device, wherein the amplifying device is provided with an amplifying output end, a signal output end and a signal input end, the FP optical filter device is provided with a filter input end and a filter output end, the filter input end is connected with the amplifying output end through a first optical fiber, the filter output end is connected with the signal input end through a second optical fiber, the amplifying device is further provided with a first amplifying light path, an output light path, a transflective piece and a first semiconductor optical amplifier, the signal input end, the first semiconductor optical amplifier and the amplifying output end are arranged along the first amplifying light path, the transflective piece is arranged on the first amplifying light path, the transflective piece is positioned at the front stage or the rear stage of the first semiconductor optical amplifier, and the transflective piece and the signal output end are.

According to the scheme, the filtering input end is connected with the amplifying output end through the first optical fiber, the filtering output end is connected with the signal input end through the second optical fiber, the signal input end, the first semiconductor optical amplifier and the amplifying output end are arranged along the first amplifying light path, signals obtained through filtering processing of the FP optical filtering device are input to the first semiconductor optical amplifier for amplifying processing, the transmission and reflection piece is arranged at the front stage or the rear stage of the first semiconductor optical amplifier, the signals passing through the signal output end before or after amplifying are output, and the cavity length of the annular cavity can be greatly reduced by integrally arranging necessary devices of the tunable laser, so that tuning of the discrete single-frequency laser and supporting of the sweep laser with higher speed are effectively realized. In the whole annular cavity, the unidirectional transmission of light is realized by connecting two optical isolators in front and at the back of the SOA chip.

The amplifying device is further provided with a first reflecting piece, the first reflecting piece is arranged on the output light path, the first reflecting piece is positioned between the signal output end and the transflective piece, and the signal output end and the amplifying output end or the signal input end are positioned on the same side.

Still further, the first reflective element is positioned on a reflective side of the transflective element.

From top to bottom, through arranging of reflection part and adjusting the light path, can make then enlarge the output and lie in same one side with signal output part or signal input part to optimize the port and arrange, make things convenient for the dish fine, do benefit to the miniaturization and arrange, also improve stability.

According to a further scheme, the amplifying device is further provided with a second semiconductor optical amplifier, the second semiconductor optical amplifier is arranged on an output light path, and the second semiconductor optical amplifier is located between the amplifying output end and the first transmission and reflection piece.

Therefore, after the signal is output from the transflective element, the signal can be amplified by the second semiconductor optical amplifier and then output.

In a further aspect, the amplifying device further includes a first fiber base and a second fiber base, wherein the output end of the first fiber is disposed on the first fiber base, and the input end of the second fiber base is disposed on the second fiber base.

Still further, the amplifying device is provided with a first optical isolator and a second optical isolator at two ends of the first semiconductor optical amplifier on the first amplifying light path, the first optical isolator is arranged at the front end of the first semiconductor optical amplifier, and the second optical isolator is arranged at the rear end of the first semiconductor optical amplifier.

Further, the first optical isolator is an optical isolator having a collimating lens, and the second optical isolator is an optical isolator having a focusing lens and a collimating lens.

It is from top to bottom, directly fix a position optic fibre through the fiber base, cooperate the one-way light effect that leads to of optical isolator to and improve coupling efficiency and whole output quality through collimating lens and focusing lens.

In a further embodiment, the first optical fiber and/or the second optical fiber is/are polarization maintaining fiber.

From the above, the polarization direction can be maintained in the annular cavity by using a sufficiently short length of fiber pigtail, and when a long cavity length is required, then connection by polarization maintaining fiber can be used.

In a further embodiment, the amplifying device further comprises a carrying base and a semiconductor refrigerator, the carrying base is disposed on the first heat conduction end of the semiconductor refrigerator, and the first semiconductor optical amplifier is disposed on the carrying base.

According to a further scheme, the amplifying device further comprises an encapsulation shell, a closed accommodating cavity is defined by the encapsulation shell, the transflective piece, the first semiconductor optical amplifier, the bearing base and the semiconductor refrigerator are arranged in the accommodating cavity, and a second heat conduction end of the semiconductor refrigerator is connected with the encapsulation shell.

From top to bottom, through the closed design of encapsulation casing, the semiconductor refrigerator can control the temperature in the encapsulation casing to and control semiconductor optical amplifier's temperature, then cool down the processing to semiconductor optical amplifier when the high temperature, heat semiconductor optical amplifier when the low temperature then, so make semiconductor optical amplifier remain throughout at best operating temperature, and then improve equipment's stability.

Drawings

Fig. 1 is a schematic structural diagram of a tunable laser according to a first embodiment of the present invention.

Fig. 2 is a schematic structural diagram of an amplifying device in a first embodiment of the tunable laser according to the present invention.

Fig. 3 is a cross-sectional view of an amplifying device in a first embodiment of a tunable laser of the present invention.

Fig. 4 is a schematic transmission diagram of a tunable laser according to an embodiment of the present invention in a single frequency mode.

Fig. 5 is a schematic transmission diagram of a tunable laser of an embodiment of the present invention in a multi-frequency mode.

Fig. 6 is a schematic structural diagram of an amplifying device in a second embodiment of the tunable laser of the present invention.

Fig. 7 is a schematic structural diagram of an amplifying device in a third embodiment of the tunable laser of the present invention.

The invention is further explained with reference to the drawings and the embodiments.

Detailed Description

Tunable laser first embodiment:

referring to fig. 1 to 3, the tunable laser includes a housing 11, an amplifying device 2 and an FP optical filter device 3, the amplifying device 2 and the FP optical filter device 3 are disposed in the housing 11, the FP optical filter device 3 includes a package housing and a FP filter device combination disposed in the package housing, the detailed structure of the FP optical filter device 3 can refer to the invention patent application with the publication number CN109557617A named as "tunable filter" in the present applicant's application, and also refer to the invention patent application with the publication number CN109491018A named as "fast tunable filter", wherein the detailed structure of the FP optical filter device is disclosed in detail, and by arranging the exit ends of two optical fiber ferrules relative to each other and matching with a combination of one or two piezoelectric ceramics, not only the slow and wide-range frequency tuning can be realized, but also the fast tuning and frequency scanning can be realized by using the high-frequency vibration. And the FP optical filter device 3 is provided with a filter input 32 and a filter output 31 on opposite ends of the package housing.

Amplifying device 2 includes encapsulation casing 21, encapsulation casing 21 includes base and lid, base and lid enclose into inclosed chamber that holds, encapsulation casing 21 is provided with on the lateral wall and amplifies output 222, signal output 223 and signal input 221, in this embodiment, signal output 223 and signal input 221 are located the same one side, signal input 221 and amplification output 222 are located opposite one side, be provided with the protection tube on input and the output, the protection tube runs through and is provided with the through-hole.

The filter input end 32 is connected with the amplification output end 222 through the first optical fiber 132, the filter output end 31 is connected with the signal input end 221 through the second optical fiber 131, and the amplification device 2 and the FP optical filter device 3 are arranged close to each other in the same shell 11, so that the length of the second optical fiber 131 of the first optical fiber 132 can be accurately controlled, the length of the optical fiber can be effectively shortened, the cavity length of the laser can be shortened, and in addition, the first optical fiber 132 and/or the second optical fiber 131 can be connected through polarization maintaining optical fibers.

The amplifying device 2 in embodiment 1 is further provided with a first amplifying optical path, an output optical path, a transflective member 251, a first semiconductor optical amplifier 261, a first reflecting member 27, a combination glass 25, an optical isolator 241, a lens 242, an optical isolator 243, a lens 244, a fiber base 271, a fiber base 272, a fiber base 273, a carrier base 231 and a semiconductor refrigerator 232, the signal input terminal 221, the optical isolator 241, the transflective member 251, the lens 242, the first semiconductor optical amplifier 261, the optical isolator 243 and the amplifying output terminal 222 are arranged in this order along the first amplifying optical path, then the transflective member 251 is located at the front stage of the first semiconductor optical amplifier 261, the fiber base 271, the optical isolator 241, the transflective member 251, the combination glass 25, the lens 242, the first semiconductor optical amplifier 261, the optical isolator 243 and the fiber base 272 are provided on the carrier base 231, the first optical fiber 132 penetrates the signal input terminal 221, the output end of the first optical fiber 132 is fixed through glue to the optical fiber base 271, the input end of the second optical fiber 132 is fixed through glue to the optical fiber base 272, combination glass 25 is synthesized by two right-angle prisms bonding, specifically, the inclined plane of a right-angle prism is connected with the right-angle face of another right-angle prism, and be provided with the transflective piece 251 between inclined plane and right-angle face, the transflective piece 251 adopts the transflective film that has the preset transflective proportion, the transmissivity is T, the reflectivity is R, be 45 contained angles between the transflective piece 251 and the first amplification light path and set up. The lens 242 and the lens 244 are focusing lenses, the optical isolator 241 is an optical isolator with a collimating lens, and the optical isolator 243 is an optical isolator with a focusing lens and a collimating lens.

The first reflecting member 27 is made of a reflecting film, the reflecting film is arranged on a right-angle surface of the combined glass 25 on the other side opposite to the transflective member 251, the first reflecting member 27 is perpendicular to the transflective member 251, the first reflecting member 27 is positioned on the reflecting side of the transflective member 251, and the lens 242 is positioned on the transmitting side of the transflective member 251. The transflective member 251, the first reflective member 27, and the signal output terminal 223 are sequentially disposed along the output optical path. The adjustment of the optical path direction by the first reflecting member 27 makes the amplification output terminal 222 and the signal input terminal 221 be located on the same side. The signal input end 221 is provided with an output optical fiber 133, the input end of the output optical fiber 133 is fixed by an optical fiber base 273 through glue, and the output end of the output optical fiber 133 is provided with a connector 12.

The semiconductor refrigerator 232 is located in the accommodating cavity and disposed on the bottom wall of the package housing 21, the carrying base 231 is disposed on the first heat conduction end of the semiconductor refrigerator 232, the second heat conduction end of the semiconductor refrigerator 232 is connected with the bottom wall of the package housing 21, since the first semiconductor optical amplifier 261 is disposed on the carrying base 231, heat conduction between the semiconductor optical amplifier and the carrying base can be realized, and the side wall of the package housing 21 is provided with the connection pin 211.

Referring to fig. 4 and 5 in conjunction with fig. 1-3, fig. 4 is a schematic diagram of transmission of a tunable laser in a single frequency mode, fig. 5 is a schematic diagram of transmission of a tunable laser in a multi-frequency mode,

after the light exits from the second optical fiber 131, the light passes through the optical isolator 241 with the collimating lens and then strikes the combined glass 25 comprising the transflective member 251 and the first reflecting member 27, the light beam passes through the front end face of the combined glass with the antireflection film and reaches the transflective member 251, where the reflected light will be reflected at the first reflecting member 27, focused through the lens 244 to the end face of the output fiber 133, thereby being coupled back to the optical fiber for outputting, the transmitted light is focused on the front end face of the first semiconductor optical amplifier 261 through the lens 242, the light intensity is amplified after the light beam passes through the first semiconductor optical amplifier 261, since a divergent light beam is emitted from the rear end face of the first semiconductor optical amplifier 261, the front end of the optical isolator 243 has a collimator lens, and the rear end of the optical isolator 243 has a focusing lens that focuses the beam onto the first optical fiber 132 for coupling back to the fiber output.

The amplifying device 2 and the FP filter device 3 are connected by optical fibers to form a ring cavity, and light can only pass through the optical amplifier in one direction under the action of two optical isolators, as shown in the figure, from left to right. In the initial stage of the ring-shaped cavity start-up, the light spontaneously radiated from the first semiconductor optical amplifier 261 passes through the optical isolator 243 and then reaches the FP filter device 3. The narrow linewidth spectrum selected by the filter passes through the filter, continues to be transmitted and emitted through the second optical fiber 131, then sequentially passes through the optical isolator 241, the transparent reflection piece 251, the lens 242, the first semiconductor optical amplifier 261 and the optical isolator 243, the light intensity of the spectrum is amplified by the first semiconductor optical amplifier 261, the amplified light returns to the optical amplifier through the filter, and secondary amplification is achieved, so that continuous circulation is achieved until the loss of the ring cavity is equal to the gain of the optical amplifier, and the loss of the ring cavity comprises the coupling loss of the light beam and the proportion of the emergent light. The drive filter scans and selects frequency, and the ring cavity can output a sweep frequency optical signal. The embodiment 1 is a front output type, and is characterized in that when a ring cavity is built, the output spectrum does not contain the spontaneous emission spectrum of an optical amplifier.

Tunable laser second embodiment:

referring to fig. 6, based on the same principle of the first embodiment, the second embodiment of the tunable laser is a signal amplification post-output, that is, the signal input end 221, the optical isolator 243, the first semiconductor optical amplifier 261, the lens 242, the transflective member 251, the optical isolator 241 and the amplification output end 222 are sequentially arranged along the first amplification optical path, then the transflective member 251 is located at the rear stage of the first semiconductor optical amplifier 261, the transflective member 251, the first reflecting member 27, the lens 244 and the signal output end 223 are sequentially arranged along the output optical path, after signal amplification, the signal is output from the signal output end 223 through reflection of the transflective member 251 and optical path adjustment of the first reflecting member 27, and the signal output end 223 of the second embodiment is located on the same side as the amplification output end 222. The embodiment 2 is a rear output type, and is characterized in that when the ring cavity is built, an output spectrum contains a spontaneous emission spectrum of the optical amplifier.

Third embodiment of tunable laser:

referring to fig. 7, based on the same principle of the first embodiment, the third embodiment of the tunable laser is a signal amplification output, the amplifying device 2 is further provided with a second semiconductor optical amplifier 262, a lens 246 and a lens 245 in an output optical path, that is, the signal input end 221, the optical isolator 241, the transflective member 251, the lens 242, the first semiconductor optical amplifier 261, the optical isolator 243 and the amplification output end 222 are sequentially arranged along the first amplification optical path, the transflective member 251, the first reflective member 27, the lens 246, the second semiconductor optical amplifier 262, the optical isolator 245 and the signal output end 223 are sequentially arranged along the output optical path, and then after the signal is reflected and output by the transflective member 251, the signal can be amplified again by the light intensity of the second semiconductor optical amplifier 262 and then output from the signal output end 223. The optical isolator 246 is an optical isolator having a focusing lens and a collimating lens, and the focusing lens is used as the lens 246. Example 3 is of the front-end output type and is matched with a rear-end secondary amplification output.

From top to bottom, pass through first optical fiber with filtering input end and amplification output end and be connected, pass through the second optical fiber with filtering output end and signal input end, utilize signal input end, first semiconductor optical amplifier and amplification output end are arranged along first enlarged light path, make FP optical filter device filtering process the signal input that reachs carry out the amplification processing to first semiconductor optical amplifier, and the setting that transflective is located the preceding stage or the back level of first semiconductor optical amplifier, make the light before enlargeing or after the amplification pass through signal output end output, through arranging the necessary device integration of tunable laser, can reduce the chamber length of annular chamber greatly, thereby realize scattered single-frequency laser tuning effectively and support the sweep laser of higher speed. On the other hand, a shorter cavity length also improves the stability of the overall optical path. In the whole annular cavity, the unidirectional transmission of light is realized by connecting two optical isolators in front and at the back of the SOA chip.

The amplifying device, the first optical fiber, the FP optical filter device and the second optical fiber form a closed annular cavity. Necessary devices are integrated, the length of the annular cavity can be shortened, the stability of the whole annular cavity can be guaranteed, and the whole annular cavity comprises an FP (Fabry-Perot) optical filter device which adopts single-mode optical fibers. The FP optical filter device based on single mode fiber has three important functions: firstly, a transmission spectrum with low loss and clean spectral line can be obtained; secondly, an irrelevant transverse mode in the annular cavity can be avoided; finally, within the limits of the FP filter mechanical dynamics and the ring cavity allowed longitudinal modes, tuning of arbitrary wavelength and frequency scanning of arbitrary speed can be achieved.