阅读说明：本技术 中红外激光器及其应用 (Mid-infrared laser and application thereof ) 是由 易剑 江南 褚伍波 王博 于 2019-04-18 设计创作，主要内容包括：本申请公开了一种中红外激光器及其应用,该激光器包括：种子光源和增益介质,种子光源产生种子光入射增益介质中后出射3.75～15μm波段的高功率中红外激光。该中红外激光功率高,能连续输出,尤其是能连续输出6～8μm波段的高功率中红外激光,可在常温下工作,有利于提高中红外激光器在各个领域的应用,该中红外激光器基于光波频率变换获得中红外激光。(The application discloses well infrared laser instrument and application thereof, this laser instrument includes: the device comprises a seed light source and a gain medium, wherein seed light generated by the seed light source is emitted into the gain medium and then is emitted out of high-power mid-infrared laser with a wave band of 3.75-15 mu m. The mid-infrared laser has high power, can continuously output, particularly can continuously output high-power mid-infrared laser with a wave band of 6-8 mu m, can work at normal temperature, is beneficial to improving the application of the mid-infrared laser in various fields, and obtains the mid-infrared laser based on light wave frequency conversion.)

1. A mid-infrared laser, comprising: the seed laser generates seed light, and the seed light is incident on the gain medium and then emits mid-infrared laser.

2. The mid-infrared laser as claimed in claim 1, wherein the seed light is an infrared laser having a wavelength ranging from 1 to 5 μm.

3. The mid-infrared laser as claimed in claim 1, wherein the seed light is an infrared laser, and the wavelength of the infrared laser is in a range of 2.5-5 μm.

4. The mid-infrared laser of claim 1, wherein the gain medium is a diamond crystal.

5. The mid-infrared laser of claim 1, wherein the gain medium is diamond crystals having a size greater than 3 x 3 mm; the impurity content is less than 1 ppm.

6. The mid-infrared laser as set forth in claim 1, wherein the mid-infrared laser comprises: and the focusing optical system is arranged between the seed light source and the gain medium and is respectively connected with the seed light source and the gain medium through optical paths.

7. The mid-infrared laser of claim 6, wherein the focusing optical system comprises: the first convex lens and the second convex lens are sequentially connected in an optical path, and the light incident surface of the first convex lens is connected with the optical path of the seed light source; and the light emergent surface of the second convex lens is connected with the gain medium optical path.

8. The mid-infrared laser of claim 6, wherein the focusing optical system comprises: one end of the optical fiber is connected with the seed light source optical path; the other end of the optical fiber is connected with the first convex lens light path.

9. The mid-infrared laser as claimed in claim 1, wherein the mid-infrared laser wavelength is 3.75-15 μm; the power of the mid-infrared laser is more than 1 kw;

preferably, the wavelength of the mid-infrared laser is 6-10 μm.

10. Use of the mid-infrared laser of any one of claims 1 to 9 in communications, laser guidance, electronic countermeasure, environmental monitoring, agriculture and food processing, medicine or non-destructive testing.

Technical Field

The application relates to a mid-infrared laser and application thereof, belonging to the field of mid-infrared lasers.

Background

The mid-infrared is located in a spectral wavelength range of 2.5-25 mu m, wherein the transmission loss of the mid-infrared laser of 1-3 mu m, 3-5 mu m and 8-13 mu m in the atmosphere is very small, and the laser has strong penetrating power for fog, smoke dust and the like, so that an atmosphere transmission window can be formed. Has potential application value in the military field. In view of the above, the research on the laser in this wavelength band has been an important branch of the optical field.

The mid-infrared ultrashort pulse laser with the pulse width of picosecond or femtosecond can realize the purposes of large capacity, high-speed remote communication, environmental monitoring, laser medical treatment, food inspection and the like, and is an important means for researching the dynamic problems of transient transition process between narrow-gap semiconductors and superlattice multi-quantum hydrazine bands, semiconductor internal photoexcitation dynamics, energy transfer between molecules and intermolecular and phase-resolving phenomena and the like.

Disclosure of Invention

According to one aspect of the application, a mid-infrared laser is provided, and the laser realizes the output of mid-infrared laser with the wavelength range of 3.75-15 mu m based on the conversion of light wave frequency.

The mid-infrared laser is characterized by comprising: the seed laser generates seed light, and the seed light is incident on the gain medium and then emits mid-infrared laser.

Optionally, the seed light is infrared laser, and the wavelength range of the infrared laser is 1-5 μm.

Optionally, the seed light is infrared laser, and the wavelength range of the infrared laser is 2.5-5 μm.

Optionally, the gain medium is a diamond crystal.

Optionally, the gain medium is diamond crystals, the diamond crystals having a size > 3 x 3 mm; the impurity content is less than 1ppm, the thermal conductivity is more than or equal to 2000W/m.K, and the transmittance of the wave band of 1-5 mu m is more than 50%.

Optionally, the mid-infrared laser comprises: and the focusing optical system is arranged between the seed light source and the gain medium and is respectively connected with the seed light source and the gain medium through optical paths.

Optionally, the focusing optical system comprises: the first convex lens and the second convex lens are sequentially connected in an optical path, and the light incident surface of the first convex lens is connected with the optical path of the seed light source; and the light emergent surface of the second convex lens is connected with the gain medium optical path.

Optionally, the focusing optical system comprises: one end of the optical fiber is connected with the seed light source optical path; the other end of the optical fiber is connected with the first convex lens light path.

Optionally, the wavelength of the mid-infrared laser is 3.75-15 μm; the power of the mid-infrared laser is more than 1 kw; preferably, the wavelength of the mid-infrared laser is 6-10 μm.

According to a further aspect of the present application there is provided the use of the mid-infrared laser described above in telecommunications, laser guidance, electronic countermeasure, environmental monitoring, agriculture and food processing, medical or non-destructive testing.

In this application, "seed light" includes a light ray or beam that can be used as a seed laser.

In the present application, "optical path connection" means connection by light or light beams transmitted between the respective light devices.

The beneficial effects that this application can produce include:

1) the mid-infrared laser provided by the application has the advantages of simple structure, capability of working at room temperature and large wavelength tuning range. The laser is focused by a light path system through a seed light source with the wavelength of 1-5 mu m, and then is tuned through a gain medium, so that the output of mid-infrared laser in a specific waveband is realized, and the power of the mid-infrared laser output by the laser can reach more than 1 kw. The laser can realize high-power broadband laser output.

2) The mid-infrared laser provided by the application can be used for communication, laser guidance, electronic countermeasure, environmental monitoring, agriculture and food processing, medicine or nondestructive testing by outputting 3.75-15 mu m waveband mid-infrared laser.

Drawings

FIG. 1 is a schematic diagram of a mid-IR laser according to one embodiment of the present application;

FIG. 2 is a graph showing the relationship between the output laser wavelength, frequency and wavelength emitted by the seed light source when a single crystal diamond is used as the gain medium according to one embodiment of the present disclosure;

FIG. 3 is a graph of the output spectrum of a seed light source (green light) at 532nm wavelength (572nm yellow light) in one embodiment of the present application;

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

Referring to fig. 1, the present application provides a mid-infrared laser, comprising: the seed laser generates seed light, and the seed light is incident on the gain medium and then emits mid-infrared laser.

The raman characteristic peak of the gain medium in this application is determined by the gain medium used, and may be one-stage or multi-stage raman characteristic peak.

The following derivation with the formula in the field illustrates the implementation principle of the technical solution of the present application:

stokes transformation may occur when light passes through the gain medium, the frequency of the light is tuned, and the frequency shift quantity Deltav is related to the Raman characteristic peak corresponding energy of the gain medium.

The energy E of a photon is determined by the planck constant h, which is 6.63 × 10, and the frequency v (or the wavelength λ), i.e., E ═ h ν ═ hc/λ (J), and if the unit of E is converted to eV, E ═ h ν ═ hc/(k λ), the planck constant h ═ hc ═ k λ^-34，k＝1.6×10^-19J/eV, light speed c is 3.0X 10⁸m/s。

Taking diamond as an example, the Raman characteristic peak of the diamond is located at 1332cm^-1Near, wavelength of λ_d＝1/1332cm^-17.5um, corresponding to energy E_d＝hc/(kλ_d)＝0.165eV。

Assuming that the input light source wavelength is λ_inpCorresponding energy E_inp＝hc/λ_inp. Then the energy of the output light after passing through the gain medium diamond is E_out＝E_inp-E_dI.e. hc/lambda_out＝hc/λ_inp-hc/λ_d，1/λ_out＝1/λ_inp-1/λ_d. Thereby obtaining an output wavelength lambda_out＝1.24/(1.24/λ_inp-0.165)。

When the gain medium used is diamond; according to λ_out＝1.24/(1.24/λ_inp-0.165), wherein λ_inpIs the wavelength of the seed light. Adjusting the wavelength lambda of the seed laser used_inpThe output of the laser with the required wavelength can be realized. In the above formula, 0.165 is the light wave energy corresponding to the raman characteristic peak of the laser gain medium. The technical solution provided by the present application is theoretically feasible.

The present application provides a correspondence between the output wavelength and frequency of an infrared laser and the wavelength emitted by a seed light source as shown in fig. 2. According to the laser provided by the application, the output wavelength is increased along with the increase of the incident laser wavelength; when the output power needs to be increased, the input laser power needs to be increased.

In summary, when the seed light source emits light with a wavelength of 2.5 to 5 μm, the wavelength range of the output of the mid-infrared laser is 3.75 to 15 μm and the frequency range of the output laser is 20 to 82THz under the tuning effect of the single crystal diamond.

Based on the formula, the seed light source satisfying the wavelength of the formula is selected, the laser with the required wavelength can be obtained through the corresponding gain medium, and the mid-infrared laser can be simply and conveniently obtained by adopting the method.

Through long-term and intensive research, a high-power intermediate infrared laser with simple design and large wavelength tuning range is prepared unexpectedly, and the intermediate infrared laser can work at normal temperature without an external cold source for cooling.

Those skilled in the art can arrange various common optical devices in the mid-infrared laser according to requirements, such as a laser amplifier, a beam expander, a collimator, a concave lens, a convex lens, a plane mirror and the like.

Optionally, the seed light source is a laser light source.

Optionally, the seed light is infrared laser, and the wavelength range of the infrared laser is 1-5 μm. Preferably, the wavelength range of the infrared laser is 2.5-5 μm.

Optionally, the mid-infrared laser comprises: and the focusing optical system is arranged between the seed light source and the gain medium and is respectively connected with the seed light source and the gain medium through optical paths.

And the focusing system is used for focusing the light waves emitted by the seed light source and improving the power density of the light emitted by the seed light source and irradiated on the gain medium. Common optical devices such as a laser amplifier and a collimator can be arranged according to requirements.

Optionally, the wavelength of the mid-infrared laser is 3.75-15 μm.

Optionally, the gain medium is a diamond crystal, the size of the diamond crystal is larger than 3 x 3mm, the impurity content is less than 1ppm, the thermal conductivity is larger than or equal to 2000W/m.K, and the transmittance of a wave band of 1-5 μm is larger than 50%.

The diamond crystal with the size is used as a gain medium, and the high-power middle infrared band laser output is favorably realized.

In yet another aspect of the application, there is provided the use of the mid-infrared laser described above in telecommunications, laser guidance, electronic countermeasure, environmental monitoring, agriculture and food processing, medical or non-destructive testing.

The following description will be made in detail with reference to a single crystal diamond as a gain medium and a laser focusing system as a preferred embodiment of the present invention, in order to more clearly understand the objects, features and advantages of the present invention. It should be noted that the focusing system in the present invention can assist in achieving the better effect of the invention, but the achievement of the object of the present invention is not dependent on the function of the focusing system. The embodiments shown in the drawings are not intended to limit the scope of the present invention, but are merely intended to illustrate the essential spirit of the technical solution of the present invention.

The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out according to conventional conditions or according to conditions recommended by the manufacturers.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In addition, any methods and materials similar or equivalent to those described herein can be used in the methods of the present invention. The preferred embodiments and materials described herein are intended to be exemplary only.

Referring to fig. 1, the mid-infrared laser includes a seed light source, a focusing system, and a gain medium. The seed light source is connected with the focusing system light path, and the focusing system is connected with the gain medium light path. And the light connected with the seed light source, the focusing system and the gain medium is transmitted through the arranged channel.

After the seed light is emitted from the seed light source, the seed light enters the focusing system, after the seed light is focused by the focusing system, the seed light enters the gain medium, and the mid-infrared laser is emitted from the other surface of the gain medium, wherein the gain medium is a diamond medium.

The seed light source emits low-power laser with the wavelength of 532nm, and the low-power laser is focused on the diamond medium after passing through the focusing system. After frequency shifting by diamond, the output of the first-order stokes raman laser at 572nm was achieved (as shown in fig. 3).

As shown in fig. 3, the laser wavelength of the mid-infrared laser output is red-shifted by 40nm compared to the wavelength of the seed light source (572 nm). Theoretical calculation proves that the frequency shift amount is 1/lambda 532 nm-1/lambda 572 nm-1332 cm^-1Characteristic Raman Peak with Diamond (1332 cm)^-1) Correspondingly, the tuning effect of the single crystal diamond on the input light source is realized.

The seed light source emits light with the wavelength, and the light passes through the focusing system and is focused on the single crystal diamond. The light passes through the single crystal diamond, undergoing a stokes shift, whose frequency is tuned. Wherein, the tuning quantity (frequency shift quantity) Deltav of the frequency is only related to the Raman characteristic peak corresponding energy of the gain medium single crystal diamond.

Energy E of photon is constant from Planckh and the frequency v (or wavelength λ), i.e. E ═ h ═ hc/λ (J), if the unit of E is converted to eV, E ═ h ═ hc/(k λ), where the planck constants h ═ 6.63 × 10-34, k ═ 1.6 × 10 ×, and k ═ 1.6 × 10^-19J/eV, light speed c is 3.0X 10⁸m/s。

The Raman characteristic peak of the diamond is 1332cm^-1Wavelength of λ_d＝1/1332cm^-17.5 μm, corresponding to energy E_d＝hc/(kλ_d)＝0.165eV。

Assuming that the input light source wavelength is λ_inpCorresponding energy E_inp＝hc/λ_inp. The energy of the output light after passing through the diamond is E_out＝E_inp-E_dI.e. hc/lambda_out＝hc/λ_inp-hc/λ_d，1/λ_out＝1/λ_inp-1/λ_d. Thereby obtaining an output wavelength lambda_out＝1.24/(1.24/λ_inp-0.165). And selecting a seed light source with a proper wavelength according to the formula, and obtaining the mid-infrared laser through the single crystal diamond.