A white light laser source generating device and method

Abstract

The present invention relates to the field of manufacturing white light laser light sources, and specifically to a device and method for generating a white light laser light source. The device includes a first pump laser for generating a first pump laser; a second pump laser for generating a second pump laser; the wavelength of the first pump laser is smaller than the wavelength of the second pump laser; a laser beam combiner for synthesizing a pump laser with the same output light path direction from a first pump laser and a second pump laser entering the laser beam combiner from different incident light paths, i.e., a combined pump laser; a periodically polarized crystal generates a violet laser from part of the first pump laser in the combined pump laser, generates a green laser from the second pump laser, and generates a white light laser from the remaining first pump laser in the violet laser, the green laser, and the combined pump laser. The periodically polarized crystal of the present invention converts two incident pump laser beams into violet laser and green laser at the same time, respectively, to meet the necessary conditions for generating a white light laser light source.

Description

Technical Field

[0001] The present invention relates to the field of manufacturing white light laser light sources, and in particular to a white light laser light source generating device and method. Background Art

[0002] The nonlinear three-wave mixing process includes frequency doubling, sum frequency and difference frequency. In the interaction of nonlinear processes, the phase matching between the interacting phases is crucial. The main phase matching methods currently include birefringence phase matching (BPM) and quasi-phase matching (QPM).

[0003] Compared with ordinary white light sources (such as sunlight, incandescent lamps, white light LED lamps, etc.), white light laser sources, short-wave laser sources and supercontinuum laser sources have the advantages of high brightness, strong peak power and wide frequency coverage. They have wide practical application value in scientific research, national defense and military, lighting, communication technology, information technology, industrial production, biomedicine, environmental testing and other fields, and have received strong attention. At present, the main way to generate white light laser sources is to continuously generate cascade radiation through the third-order nonlinear process of femtosecond lasers in photonic crystal fibers, or to generate them by using the high-order harmonic process in periodically polarized crystals.

[0004] The prior art does not solve the technical problem of how to generate a white light laser source in a single cycle quasi-phase matching process. Summary of the invention

[0005] In order to solve the above technical problems, one of the objectives of the present invention is to provide a white light laser source generating device, which can generate a white light laser source in a single cycle quasi-phase matching process.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A white light laser source generating device, the device comprising the following components:

[0008] A first pump laser, used to generate a first pump laser;

[0009] A second pump laser, used to generate a second pump laser;

[0010] The wavelength of the first pump laser is shorter than the wavelength of the second pump laser;

[0011] A laser beam combiner, used for combining a first pump laser and a second pump laser entering the laser beam combiner from different incident light paths into a pump laser with the same outgoing light path direction, i.e., a combined pump laser;

[0012] The periodically polarized crystal is used to generate violet laser light from part of the first pump laser light in the combined pump laser light, generate green laser light from the second pump laser light, and generate white laser light from the remaining first pump laser light in the violet laser light, the green laser light and the combined pump laser light.

[0013] Furthermore, the device also includes a temperature control component for adjusting the temperature of the periodically polarized crystal.

[0014] Further preferably, the device further comprises a first polarization and focusing module located between the first pump laser and the laser beam combiner, wherein the first polarization and focusing module is used to transmit the first pump laser output by the first pump laser to the laser beam combiner.

[0015] Further preferably, the first polarization and focusing module comprises a first quarter-wave plate, a first half-wave plate and a first focusing lens which are sequentially arranged along the direction of the output light path of the first pump laser.

[0016] Further preferably, the second pump laser is a fiber laser, and the device further comprises a single-mode optical fiber and a fiber coupling head sequentially arranged along the direction of the output light path of the second pump laser;

[0017] The device also includes a second polarization and focusing module located between the optical fiber coupling head and the laser beam combiner, and the second polarization and focusing module is used to transmit the second pump laser output by the optical fiber coupling head to the laser beam combiner.

[0018] More preferably, the second polarization and focusing module comprises a second quarter wave plate, a second half wave plate, and a second focusing lens which are sequentially arranged along the direction of the output light path of the optical fiber coupling head.

[0019] More preferably, the device further comprises a filter located in the direction of the outgoing light path of the periodically polarized crystal, and the filter is used to filter out the second pump laser doped in the white light laser.

[0020] Furthermore, the device also includes a first focusing lens located in the direction of the output light path of the first pump laser, and a second focusing lens located in the direction of the output light path of the second pump laser;

[0021] The first focusing lens is coated with a first anti-reflection film, and the first anti-reflection film is used to improve the transmittance of the first focusing lens to the first pump laser;

[0022] The second focusing lens is coated with a second anti-reflection film, and the second anti-reflection film is used to improve the transmittance of the second focusing lens to the second pump laser;

[0023] The end face of the laser beam combiner facing the incident optical path direction of the first pump laser is also coated with a first anti-reflection film, which is used to improve the transmittance of the laser beam combiner to the first pump laser;

[0024] The end face of the laser beam combiner facing the incident optical path direction of the second pump laser is coated with a reflective film, and the reflective film is used to improve the reflectivity of the laser beam combiner reflecting the second pump laser into the periodically polarized crystal.

[0025] A second object of the present invention is to provide a method for generating a white light laser source, comprising the following steps:

[0026] S1, the first pump laser outputs a first pump laser with a wavelength of 760nm to 800nm; the second pump laser outputs a second pump laser with a wavelength of 1000nm to 1100nm;

[0027] S2, the laser beam combiner adjusts the first pump laser and the second pump laser in step S1 to the same optical path direction;

[0028] S3, the first pump laser and the second pump laser located in the same optical path direction in step S2 enter the periodically polarized crystal, the periodically polarized crystal generates the first pump laser into a violet laser with a wavelength of 380nm to 400nm, and the periodically polarized crystal generates the second pump laser into a green laser with a wavelength of 500nm to 550nm;

[0029] S3, the periodically polarized crystal generates white light laser output from the violet laser with a wavelength of 380nm to 400nm, the green laser with a wavelength of 500nm to 550nm, and the first pump laser.

[0030] Furthermore, the temperature of the periodically poled crystal is 21° C. to 22° C., the wavelength of the first pump laser is 784 nm, the wavelength of the second pump laser is 1063.8 nm, the wavelength of the violet laser is 392 nm, and the wavelength of the green laser is 531.9 nm.

[0031] The beneficial effects of the present invention are as follows:

[0032] (1) Purple laser, green laser and pump laser of specific wavelength are necessary conditions for generating white laser light source. The periodically polarized crystal of the present invention converts incident pump laser with wavelength of 760nm-800nm ​​and pump laser with wavelength of 1000nm-1100nm into purple laser and green laser respectively at the same time, that is, when part of pump laser with wavelength of 760nm-800nm ​​is converted into purple laser, pump laser with wavelength of 1000nm-1100nm is inevitably converted into green laser, so as to meet the necessary conditions for generating white laser light source.

[0033] From the above analysis, it can be seen that the present invention generates a white light laser source through single-cycle quasi-phase matching of periodically polarized crystals. The nonlinear crystal manufacturing process used in single-cycle quasi-phase matching is simple and has a higher conversion efficiency than other nonlinear conversion processes. Single cycle means that the polarized crystal can complete the operation in a single polarization cycle.

[0034] (2) The present invention generates a white light laser source through quasi-phase matching of a single cycle, and can simultaneously improve the conversion rate of a pump laser with a wavelength of 760nm to 800nm ​​into a violet laser and a pump laser with a wavelength of 1000nm to 1100nm into a green laser, so as to increase the number of violet lasers and green lasers without increasing the power of the pump laser used to generate the two pump lasers, thereby achieving a higher nonlinear conversion rate at a lower pump power. The nonlinear conversion is the conversion of a pump laser with a wavelength of 1000nm to 1100nm into a green laser, or the conversion of a pump laser with a wavelength of 760nm to 800nm ​​into a violet laser.

[0035] (3) Two different pump laser beams enter the periodically polarized crystal from different optical path directions. The periodically polarized crystal cannot generate a white light laser source through these two pump laser beams with different optical path directions. Therefore, the present invention designs a laser beam combiner that can combine light beams with different optical path directions into a light beam with the same optical path direction to meet the requirements of the periodically polarized crystal for the optical path direction, thereby generating a white light laser source.

[0036] (4) The white light laser light source produced by the present invention can play an important role in microscopic imaging and illumination. In addition, the present invention produces a white light laser light source by achieving quasi-phase matching of a single period through a periodically polarized crystal. The interacting light waves of the white light laser light source propagate along the optical axis without walk-off effect, thereby improving the quality of the white light laser light source of the present invention.

[0037] (5) The present invention designs the temperature of the periodically poled crystal to be 21°C to 22°C, at which temperature the conversion rate of the pump laser with a wavelength of 784nm into violet laser and the conversion rate of the pump laser with a wavelength of 1063.8nm into green laser both reach the maximum at the same time. In this way, the number of white light laser sources generated by the present invention is increased without increasing the pump power used to generate the pump laser.

[0038] (6) The ambient temperature of the periodically polarized crystal is different, and the conversion rate of the pump laser to the green laser or the violet laser is different. The ratio between the green laser, the violet laser, and the pump laser changes, and the color of the white light laser source generated by the three will be different.

[0039] The present invention places a periodically polarized crystal in a temperature control component. By adjusting the temperature of the periodically polarized crystal through the temperature control component, the conversion rate of the pump laser into the violet laser and the conversion rate of the pump laser into the green laser can be adjusted, and then the ratio among the green laser, the violet laser and the pump laser can be adjusted, so that the color of the white light laser source can be adjusted as needed, so as to expand the application range of the white light laser source of the present invention.

[0040] (7) The first polarization and focusing module is used for adjusting and controlling the polarization of the first pump laser, and is used for adjusting the polarization state of the first pump laser to be along the incident direction of the periodically polarized crystal. The second polarization and focusing module is used for adjusting and controlling the polarization of the second pump laser, and is used for adjusting the polarization state of the second pump laser to be along the incident direction of the periodically polarized crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the overall structure of the device of the present invention;

[0042] Figure 2 is the conversion rate of the pump laser of the periodically polarized crystal of the present invention into green laser or violet laser at different temperatures;

[0043] Figure 3 The periodically polarized crystal of the present invention converts the pump laser into other lasers of different wavelengths at different polarization periods;

[0044] Figure 4 It is the white light laser light source produced by the present invention.

[0045] The meanings of the symbols in the figure are as follows:

[0046] 1-first pump laser 2-first polarization and focusing module 21-first quarter wave plate

[0047] 22-first half-wave plate 23-first focusing lens 3-second pump laser 31-single-mode optical fiber

[0048] 32-fiber coupling head 4-second polarization and focusing module 41-second quarter wave plate

[0049] 42-second half-wave plate 43-second focusing lens 5-laser beam combiner 6-periodically polarized crystal

[0050] 61-Temperature control component

[0051] 7-collimation and filtering module 71-filter 72-lens 8-white paper DETAILED DESCRIPTION

[0052] The following is a clear and complete description of the technical solution of the present invention in combination with the embodiments and the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] Example 1

[0054] A white light laser source generating device, such as Figure 1 As shown, the device includes the following components:

[0055] A first pump laser 1, used to generate a first pump laser;

[0056] A second pump laser 3, used to generate a second pump laser;

[0057] The wavelength of the first pump laser is shorter than the wavelength of the second pump laser;

[0058] a first polarization and focusing module 2 located between the first pump laser 1 and the laser beam combiner 5, the first polarization and focusing module 2 being used to transmit the first pump laser output by the first pump laser 1 to the laser beam combiner 5;

[0059] A second polarization and focusing module 4 located between the optical fiber coupling head 32 and the laser beam combiner 5, and the second polarization and focusing module 4 is used to transmit the second pump laser output by the optical fiber coupling head 32 to the laser beam combiner 5;

[0060] The laser beam combiner 5 is used to combine the first pump laser and the second pump laser entering the laser beam combiner 5 from different incident light paths into a pump laser with the same outgoing light path direction, i.e., a combined pump laser. The first pump laser and the second pump laser in the combined pump laser retain their respective properties. The combined pump laser only makes the light path directions of the pump lasers contained therein the same, so as to meet the requirements of the periodically polarized crystal 6 on the light path direction entering therein;

[0061] The periodically polarized crystal 6 is used to convert part of the first pump laser in the combined pump laser into violet laser, convert the second pump laser into green laser, and convert the remaining first pump laser in the violet laser, green laser and combined pump laser into white laser. They are introduced below:

[0062] The first pump laser 1 is a titanium sapphire laser with an output power greater than 1.5 W and a frequency line width of 100 kHz.

[0063] The first polarization and focusing module 2 comprises a first quarter wave plate 21, a first half wave plate 22 and a first focusing lens 23 which are sequentially arranged along the direction of the output light path of the first pump laser 1. The first focusing lens 23 is coated with a first anti-reflection film, which is used to improve the transmittance of the first focusing lens 23 to the first pump laser.

[0064] The second pump laser 3 is a fiber laser with a maximum output power of 5W, and the laser is output to the free space through a fiber collimator. A single-mode fiber 31 and a fiber coupling head 32 are sequentially arranged along the direction of the output light path of the second pump laser 3. The second polarization and focusing module 4 includes a second quarter-wave plate 41, a second half-wave plate 42, and a second focusing lens 43, which are sequentially arranged along the direction of the output light path of the fiber coupling head 32. The second focusing lens 43 is coated with a second anti-reflection film, and the second anti-reflection film is used to improve the transmittance of the second focusing lens 43 to the second pump laser.

[0065] The end face of the laser beam combiner 5 facing the incident optical path of the first pump laser is coated with a first anti-reflection film, which is used to improve the transmittance of the laser beam combiner 5 to the first pump laser. The end face of the laser beam combiner 5 facing the incident optical path of the second pump laser is coated with a reflective film, which is used to improve the reflectivity of the laser beam combiner 5 reflecting the second pump laser into the periodically polarized crystal 6.

[0066] The periodically polarized crystal 6 is a PPKTP crystal, which can simultaneously meet the first-order type 0 phase matching and the third-order type 0 phase matching at a polarization period of 8.95 microns. The advantage of type 0 matching is that the maximum nonlinear coefficient of the crystal can be utilized, and the conversion efficiency is high. The cross-sectional size of the periodically polarized crystal 6 is 1mm*2mm, and the length is 30mm. The temperature of the periodically polarized crystal 6 can be adjusted by the temperature control component 61 to adjust the conversion rate of the periodically polarized crystal 6 to the pump laser. The temperature control component 61 is a temperature control furnace with a maximum output current of 2A, a temperature control range of 0-100°C, and a temperature control accuracy of 0.001°C.

[0067] A filter 71 and a lens 72 are arranged along the direction of the outgoing light path of the periodically polarized crystal 6. The filter 71 is used to filter out the second pump laser doped in the white light laser. The filter 71 and the lens 72 constitute a collimation and filtering module 7. The collimation and filtering module 7 is used to transmit the white light laser light source from which the second pump laser is filtered out to a white paper 8. The white paper 8 is used to display the effect of the white light laser light source of the present invention.

[0068] Example 2

[0069] On the basis of Example 1, a method for generating a white light laser source, wherein the temperature of the periodically polarized crystal 6 is set to 21° C. to 22° C., comprises the following steps:

[0070] S1, the first pump laser 1 outputs a first pump laser with a wavelength of 760nm to 800nm; the second pump laser 3 outputs a second pump laser with a wavelength of 1000nm to 1100nm;

[0071] S2, the laser beam combiner 5 combines the first pump laser and the second pump laser in step S1 so that the optical paths of all pump lasers emitted from the laser beam combiner 5 are in the same optical path direction;

[0072] S3, the first pump laser and the second pump laser located in the same optical path direction in step S2 enter the periodic polarization crystal 6, the periodic polarization crystal 6 generates the first pump laser into a violet laser with a wavelength of 380nm to 400nm, and the periodic polarization crystal 6 generates the second pump laser into a green laser with a wavelength of 500nm to 550nm;

[0073] S3, the periodically poled crystal 6 generates white light laser output from the violet laser with a wavelength of 380nm to 400nm, the green laser with a wavelength of 500nm to 550nm and the first pump laser.

[0074] In the above steps, the periodically polarized crystal 6 converts the first pump laser with a wavelength of 760nm to 800nm ​​into a violet laser with a wavelength of 380nm to 400nm, and converts the second pump laser with a wavelength of 1000nm to 1100nm into a green laser with a wavelength of 500nm to 550nm, all based on the following principles:

[0075] like Figure 3 As shown, when the polarization period Λ of the periodically poled crystal 6 is 8.95 um, the first-order 0-type quasi-phase matching ( Figure 3 The curve corresponding to 3Λzzz in the figure) and the third-order type 0 quasi-phase matching ( Figure 3 The curve corresponding to Λzzz in ). For the frequency doubling process, it is necessary to satisfy the conservation of energy and momentum. The conservation of energy requires 2ω p =ω SHG , the conservation of momentum requires Δk = k SHG -2k p +2πm / Λ=0, where k q =2πn q / λ q (q=p,SHG) is the wave vector of pump and double-frequency light, m ​​is the order of quasi-phase matching, p is pump light, SHG is double-frequency light, n p is the wave vector of the pump light, n SHG is the wave vector of the doubled frequency light, λp is the wavelength of the pump light, λ SHGTherefore, by designing the polarization period Λ of the periodic polarization crystal 6, we can obtain the quasi-phase matching type of the periodic polarization crystal 6. The nonlinear conversion process that satisfies the conditions can be determined through the phase matching relationship. By substituting the dispersion equation of the PPKTP crystal into the phase matching relationship, we can theoretically determine the nonlinear process that satisfies the phase matching. The result is as follows: Figure 3 As shown, from the figure we can see that four effective nonlinear conversion processes can occur simultaneously under the same polarization period, namely 1st-order type-0 matching, 3rd-order type-0 matching, 1st-order type-2 matching and 3rd-order type-1 matching. In the example of the present invention, we use 1st-order type-0 matching and 3rd-order type-0 matching to achieve the generation of white light laser.

[0076] Example 3

[0077] On the basis of Example 2, the polarization period Λ of the periodically polarized crystal 6 of this embodiment is 8.95um, the wavelength of the first pump laser is 784nm, the wavelength of the second pump laser is 1063.8nm, the wavelength of the violet laser is 392nm, and the wavelength of the green laser is 531.9nm. Figure 2 As shown, the horizontal axis is the temperature of the periodically polarized crystal 6, and the vertical axis is the conversion rate of the periodically polarized crystal 6 from the first pump laser with a wavelength of 784nm to the purple laser with a wavelength of 392nm and the conversion rate of the periodically polarized crystal 6 from the second pump laser with a wavelength of 1063.8nm to the green laser with a wavelength of 531.9nm. Figure 2 It can be seen that at the same temperature, the conversion rates of the two are the same. In this embodiment, the temperature of the periodically poled crystal 6 is set to 21.8° C., at which time the conversion rates of the two are the highest. Figure 4 The invention relates to a white light laser light source produced by the method of the invention.

Claims

1. A white light laser source generating device, characterized in that: The device includes the following components: A first pump laser (1), used to generate a first pump laser; A second pump laser (3), used for generating a second pump laser; The wavelength of the first pump laser is shorter than the wavelength of the second pump laser; A laser beam combiner (5) is used to combine a first pump laser and a second pump laser entering the laser beam combiner (5) from different incident light paths into a pump laser with the same outgoing light path direction, i.e., a combined pump laser; The periodically polarized crystal (6) is used to generate violet laser light from part of the first pump laser light in the combined pump laser light, generate green laser light from the second pump laser light, and combine the violet laser light, the green laser light and the remaining first pump laser light in the combined pump laser light to generate white laser light based on a single-cycle quasi-phase matching process; Wherein, the wavelength of the first pump laser is 760nm-800nm.

2. The white light laser source generating device according to claim 1, characterized in that: The device also includes a temperature control component (61) for adjusting the temperature of the periodically poled crystal (6).

3. The white light laser source generating device according to claim 1, wherein: The device also comprises a first polarization and focusing module (2) located between the first pump laser (1) and the laser beam combiner (5), wherein the first polarization and focusing module (2) is used to transmit the first pump laser output by the first pump laser (1) to the laser beam combiner (5).

4. The white light laser source generating device as claimed in claim 3, characterized in that: The first polarization and focusing module (2) comprises a first quarter-wave plate (21), a first half-wave plate (22) and a first focusing lens (23) which are sequentially arranged along the direction of the output light path of the first pump laser (1).

5. The white light laser source generating device as claimed in claim 1, characterized in that: The second pump laser (3) is a fiber laser, and the device further comprises a single-mode optical fiber (31) and an optical fiber coupling head (32) which are sequentially arranged along the direction of the output light path of the second pump laser (3); The device also includes a second polarization and focusing module (4) located between the optical fiber coupling head (32) and the laser beam combiner (5), wherein the second polarization and focusing module (4) is used to transmit the second pump laser output by the optical fiber coupling head (32) to the laser beam combiner (5).

6. The white light laser source generating device as claimed in claim 5, characterized in that: The second polarization and focusing module (4) comprises a second quarter-wave plate (41), a second half-wave plate (42), and a second focusing lens (43) which are sequentially arranged along the direction of the outgoing light path of the optical fiber coupling head (32).

7. The white light laser source generating device according to any one of claims 1 to 6, characterized in that: The device also comprises a filter (71) located in the direction of the outgoing light path of the periodically polarized crystal (6), wherein the filter (71) is used to filter out the second pump laser doped in the white light laser.

8. The white light laser source generating device as claimed in claim 1, characterized in that: The device also includes a first focusing lens (23) located in the direction of the output light path of the first pump laser (1), and a second focusing lens (43) located in the direction of the output light path of the second pump laser (3); The first focusing lens (23) is coated with a first anti-reflection film, and the first anti-reflection film is used to increase the transmittance of the first focusing lens (23) to the first pump laser; The second focusing lens (43) is coated with a second anti-reflection film, and the second anti-reflection film is used to increase the transmittance of the second focusing lens (43) to the second pump laser; The end surface of the laser beam combiner (5) facing the incident optical path of the first pump laser is also coated with a first anti-reflection film, so as to increase the transmittance of the laser beam combiner (5) to the first pump laser; The end face of the laser beam combiner (5) facing the incident optical path direction of the second pump laser is coated with a reflective film, and the reflective film is used to increase the reflectivity of the laser beam combiner (5) reflecting the second pump laser into the periodically polarized crystal (6).

9. A method for generating a white light laser source based on the white light laser source generating device according to claim 1, characterized in that: The steps include: S1, the first pump laser (1) outputs a first pump laser with a wavelength of 760nm to 800nm; the second pump laser (3) outputs a second pump laser with a wavelength of 1000nm to 1100nm; S2, the laser beam combiner (5) adjusts the first pump laser and the second pump laser in step S1 to have the same optical path direction; S3, the first pump laser and the second pump laser located in the same optical path direction in step S2 enter the periodically polarized crystal (6), the periodically polarized crystal (6) generates a violet laser with a wavelength of 380nm to 400nm from the first pump laser, and the periodically polarized crystal (6) generates a green laser with a wavelength of 500nm to 550nm from the second pump laser; S3, the periodically polarized crystal (6) combines the violet laser with a wavelength of 380nm to 400nm, the green laser with a wavelength of 500nm to 550nm and the first pump laser to generate white light laser output.

10. The method for generating a white light laser source according to claim 9, wherein: The temperature of the periodically polarized crystal (6) is 21° C. to 22° C., the wavelength of the first pump laser is 784 nm, the wavelength of the second pump laser is 1063.8 nm, the wavelength of the violet laser is 392 nm, and the wavelength of the green laser is 531.9 nm.

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