A compact multi-wavelength laser

Abstract

The application discloses a compact multi-wavelength laser, which comprises a pump module, a shaping module, a first resonant cavity mirror, a first crystal, a second crystal, a Q-switching module and a second resonant cavity mirror arranged along an optical path; the shaping module is used for beam shrinking and collimation of pump light; the second crystal is used for generating excitation light, frequency-doubled light, signal light and idler light after receiving the pump light; the first crystal is used for polarizing the excitation light; the first resonant cavity mirror and the second resonant cavity mirror constitute a resonant cavity of the compact multi-wavelength laser; the second crystal further comprises a temperature control module connected thereto, so that the second crystal with a polarization period Lambda is maintained at a temperature T, which can simultaneously generate the frequency-doubled light, the signal light and the idler light in the resonant cavity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid-state laser, more particularly, to a compact multi-wavelength laser. BACKGROUND

[0002] With the rapid development of various laser devices and technologies, the laser field is developing towards compact size, high conversion efficiency and high beam quality. Multi-wavelength lasers, which can output multiple wavelengths of laser light from one laser, have been continuously developed in recent years and are widely used in medical treatment, distance measurement, imaging and spectroscopy. Among them, 0.8 μm and 1.5 μm laser outputs are within the atmospheric window range and can be widely used in the field of space laser communication; 1 μm pulse laser can be widely used in laser ranging and laser imaging; blue-green laser near 0.5 μm can be used for underwater space communication or submarine communication.

[0003] The common multi-wavelength laser in the prior art is a dual-wavelength laser, and there are few lasers that simultaneously output more than two wavelengths. SUMMARY

[0004] In view of at least one defect or improvement demand of the prior art, the present application provides a compact multi-wavelength laser to eliminate one or more defects of the prior art.

[0005] To achieve the above-mentioned purpose, according to the first aspect of the present application, a compact multi-wavelength laser is provided, which comprises:

[0006] a pump module, a shaping module, a first resonant cavity mirror, a first crystal, a second crystal, a Q-switching module and a second resonant cavity mirror arranged along an optical path;

[0007] The shaping module is used for beam collimation of the pump light generated by the pump module;

[0008] The second crystal is used for generating excitation light after receiving the pump light; is also used for generating frequency-doubled light by nonlinear effect of linearly polarized excitation light under temperature T and polarization period Λ; and is also used for generating signal light and idler light by optical parametric oscillation of frequency-doubled light under temperature T and polarization period Λ;

[0009] The first crystal is used for making the excitation light into linearly polarized light;

[0010] The first resonant cavity mirror is used for making the pump light transmittable and the excitation light, the frequency-doubled light, the signal light and the idler light highly reflective; the second resonant cavity mirror is used for making the pump light highly reflective, the excitation light, the frequency-doubled light and the signal light partially transmittable, and the idler light transmittable; and the first resonant cavity mirror and the second resonant cavity mirror constitute a resonant cavity of the compact multi-wavelength laser.

[0011] The second crystal also includes a connected temperature control module, which maintains the second crystal with a polarization period Λ at a temperature T that allows the frequency-doubled light, the signal light, and the idler light to be generated simultaneously within the resonant cavity.

[0012] Furthermore, the aforementioned compact multi-wavelength laser also includes:

[0013] The first crystal and the second crystal are lithium niobate crystals, and the first crystal and the second crystal are bonded together.

[0014] Furthermore, the aforementioned compact multi-wavelength laser also includes:

[0015] The first crystal is a scandium-doped lithium niobate crystal or a magnesium-doped lithium niobate crystal.

[0016] Furthermore, the aforementioned compact multi-wavelength laser also includes:

[0017] The second crystal is an Nd:MgO:LiNbO3 crystal.

[0018] Furthermore, the aforementioned compact multi-wavelength laser also includes:

[0019] The polarization period Λ of the second crystal is in the range of 7~9μm.

[0020] Furthermore, the aforementioned compact multi-wavelength laser also includes:

[0021] The temperature T of the second crystal is set according to the polarization period Λ.

[0022] Furthermore, the aforementioned compact multi-wavelength laser also includes:

[0023] The polarization period of the second crystal is Λ=7.9μm, and the temperature is T=27.1±0.1℃.

[0024] Furthermore, the aforementioned compact multi-wavelength laser also includes:

[0025] The Q-switching module includes a Q-switching crystal, a signal generator, an electro-optic driver, and electrodes. The Q-switching crystal is a lithium niobate crystal, and the Q-switching crystal is bonded to the second crystal.

[0026] Furthermore, the aforementioned compact multi-wavelength laser also includes:

[0027] The resonant cavity is a confocal cavity.

[0028] Furthermore, the aforementioned compact multi-wavelength laser also includes:

[0029] The shaping module is a single lens or a group of lenses.

[0030] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0031] (1) The compact multi-wavelength laser provided by the present invention uses a single crystal to achieve four-wavelength coaxial output with a high degree of integration;

[0032] (2) The compact multi-wavelength laser provided by the present invention uses the same matrix crystal for the first crystal and the second crystal, so that the first crystal and the second crystal can be connected by bonding, thereby making the laser structure compact, the cavity length short, reducing the optical parametric oscillation threshold, and improving the optical-to-optical conversion efficiency.

[0033] (3) The compact multi-wavelength laser provided by the present invention can achieve four-wavelength output at room temperature without the need for harsh environmental conditions, thus improving its applicability;

[0034] (4) The compact multi-wavelength laser provided by the present invention adopts electro-optic Q-switching. The Q-switching crystal, the first crystal, and the second crystal are made of the same matrix crystal, so that the first crystal, the second crystal and the Q-switching module are connected by bonding, which further makes the laser structure compact and reduces the size of the laser. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of a compact multi-wavelength laser provided in an embodiment of the present invention.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1-Pump module; 2-Shaping module; 3-First resonant cavity mirror; 4-First crystal; 5-Second crystal; 6-Electro-optic driver; 7-Signal generator; 8-Q-switched crystal; 9-Second resonant cavity mirror. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0040] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0041] like Figure 1 As shown, as a first embodiment of the present invention, a compact multi-wavelength laser is provided. This laser can achieve coaxial output of four laser wavelengths at room temperature. It has a compact structure and can be widely used in multi-wavelength ranging, multi-wavelength laser detection and imaging, as well as space laser communication and underwater laser communication. The compact multi-wavelength laser includes a pump module 1, a shaping module 2, a first resonant cavity mirror 3, a first crystal 4, a second crystal 5, a Q-switching module, a temperature control module, and a second resonant cavity mirror 9 arranged in an optical path.

[0042] In this embodiment, pump module 1 outputs a laser with a center wavelength of 813nm as the pump light; shaping module 2 is a lens group composed of multiple lenses, used for beam collimation of the 813nm laser. In other embodiments, a single lens can also achieve the function of the above-mentioned lens group.

[0043] In this embodiment, the first resonant cavity mirror 3 is a plano-concave mirror, with one side coated with an 813nm laser antireflection film, having a transmittance greater than 98%; the other side is coated with high-reflectivity films for 1084nm, 542nm, 830nm, and 1510nm lasers, with reflectivity greater than 99%, and an 813nm laser antireflection film, with a transmittance greater than 98%, and a radius of curvature of 200mm. The second resonant cavity mirror 9 is a plano-concave mirror, with both sides coated with partial-transmittance films for 1084nm (5% transmittance), 542nm (5% transmittance), and 830nm (45%-55% transmittance) lasers, an antireflection film for 1510nm (transmittance greater than 90%) lasers, and a high-reflectivity film for 813nm lasers (reflectivity greater than 99%), and a radius of curvature of 200mm. The first resonant cavity mirror 3 and the second resonant cavity mirror 9 form a confocal resonant cavity, controlling the cavity film size and increasing the 542nm laser power density, thereby improving the optical parametric oscillation conversion efficiency.

[0044] In this embodiment, the first crystal 4 is a scandium-doped lithium niobate crystal with a scandium oxide doping concentration of 1.5 mol%, used to improve the optical damage threshold of the lithium niobate crystal. The first crystal 4 is also cut with Brewster angles corresponding to a wavelength of 1084 nm. The beveled surface is coated with high reflectivity films (all reflectivity greater than 99%) for 813 nm, 1084 nm, 542 nm, 830 nm and 1510 nm lasers, and the right-angled surface is coated with antireflection films (all transmittance greater than 98%) for 813 nm, 1084 nm, 542 nm, 830 nm and 1510 nm lasers. Furthermore, the first crystal 4 is bonded to the left side of the second crystal 5 by diffusion bonding.

[0045] In this embodiment, the second crystal 5 is an Nd:MgO:LiNbO3 crystal, and its polarization period is designed to be 7~9 μm to achieve both nonlinear effects to generate frequency-doubled light and optical parametric oscillations to generate signal light and idler light. The preferred polarization period of the second crystal 5 is 7.9 μm. The two ends of the second crystal 5 are coated with antireflection films of 813 nm, 1084 nm, 542 nm, 830 nm, and 1510 nm (all with transmittance greater than 98%), Nd... 3+ The ion doping concentration is 0.5%, and the center of the Nd:MgO:LiNbO3 crystal is 100 mm away from the right side of the first resonant cavity mirror 3.

[0046] The Q-switching module in this embodiment includes a Q-switching crystal 8, a signal generator 7, an electro-optic driver 6, and electrodes (not shown in the figure). The Q-switching crystal 8 is a lithium niobate (LiNbO3) crystal, cut at 45°-z, with antireflection coatings of 813nm, 1084nm, 542nm, 830nm, and 1510nm at both ends (all with transmittance greater than 98%). The Q-switching crystal 8 is bonded to the right side of the second crystal 5 by diffusion bonding. The signal generator 7 is used to provide pulse signals. The electro-optic driver 6 is used to receive the pulse signals generated by the signal generator 7 and generate a λ / 4 high-voltage pulse corresponding to 1084nm. The electrodes are used to load the high-voltage pulse onto the Q-switching crystal 8, thereby generating a specific loss at 1084nm in the cavity, thus realizing Q-switched pulsed laser output.

[0047] The working principle of the Q-switching module is as follows: the signal generator 7 generates a pulse signal; the electro-optic driver 6 is used to convert the pulse signal generated by the signal generator 7 into a high-voltage electrical signal to drive and control the Q-switched crystal 8, control the loss in the resonant cavity, and thus generate pulsed laser.

[0048] The temperature control module is used to control the temperature of the second crystal 5, and the temperature of the second crystal 5 needs to be set according to its polarization period. In this embodiment, when the polarization period Λ of the second crystal 5 is 7.9 μm, the temperature is set to 27.1 ± 0.1 °C.

[0049] The principle of this invention is as follows:

[0050] Nd:MgO:LiNbO3 crystal is an anisotropic crystal, with a nonlinear coefficient d33 = 20 pm / V. According to the quasi-phase matching theory, when the quasi-phase matching condition Δk = 0 is satisfied, we have... .in, For the pump light refractive index, For signal light refractive index, For the refractive index of idle frequency light, For pump light wavelength, For signal light wavelength, Λ is the idler wavelength and Λ is the polarization period. , , All satisfy the Sellmeier equation and are temperature-dependent. Therefore, the polarization period of the Nd:MgO:LiNbO3 crystal is designed, and the crystal temperature is controlled so that at the same temperature T and the same polarization period Λ, a 1084nm laser generates a second harmonic through the Nd:MgO:LiNbO3 crystal, outputting a 542nm laser. Simultaneously, through resonant cavity design, the cavity film volume is reduced by utilizing a confocal cavity, increasing the power density of the 542nm laser on the Nd:MgO:LiNbO3 crystal. This allows the 542nm laser to undergo optical parametric oscillation through the Nd:MgO:LiNbO3 crystal at the same temperature T and polarization period Λ, achieving the output of 830nm and 1510nm signal light and idler light.

[0051] Based on the above principles, the working principle of this invention is as follows:

[0052] A high-energy 813nm laser is injected into a second crystal after passing through a Brewster-angle-cut first crystal. Combined with a Q-switching module, this generates a 1084nm polarized pulsed laser. Under cavity mirror coating control, most of the 1084nm laser returns to the second crystal within the resonant cavity. Within this second crystal, maintained at a temperature of 27.1℃ and a polarization period of 7.9µm, a second harmonic with a wavelength of 542nm is generated. Under further cavity mirror coating control, most of the 542nm laser returns to the second crystal within the resonant cavity. Within this second crystal, also at 27.1℃ and with a polarization period of 7.9µm, optical parametric oscillation occurs, producing 830nm and 1510nm laser outputs. Based on the second resonant cavity coating control, the 542nm, 830nm, 1084nm, and 1510nm lasers are output coaxially with a common aperture. Once the laser reaches a stable state, coaxial output of the 542nm, 830nm, 1084nm, and 1510nm lasers with a common aperture can be achieved.

[0053] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0054] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A compact multi-wavelength laser, characterized in that, include: A pump module, a shaping module, a first resonant cavity mirror, a first crystal, a second crystal, a Q-switching module, and a second resonant cavity mirror are arranged along the optical path. The shaping module is used to collimate and reduce the pump light generated by the pump module. The second crystal is used to receive the pump light and generate excitation light; it is also used to generate frequency-doubled light by linearly polarized excitation light through nonlinear effects at temperature T and polarization period Λ; it is also used to generate signal light and idler light by frequency-doubled light through optical parametric oscillation at temperature T and polarization period Λ. The first crystal is used to convert the excitation light into linearly polarized light; The first resonant cavity mirror is used to increase the transmittance of the pump light, and to make the excitation light, the frequency-doubled light, the signal light, and the idler light highly reflective; the second resonant cavity mirror is used to make the pump light highly reflective, and to make the excitation light, the frequency-doubled light, and the signal light partially transmittable, and to increase the transmittance of the idler light; the first resonant cavity mirror and the second resonant cavity mirror constitute the resonant cavity of the compact multi-wavelength laser; The second crystal also includes a connected temperature control module, which maintains the second crystal with a polarization period Λ at a temperature T that allows the frequency-doubled light, the signal light, and the idler light to be generated simultaneously in the resonant cavity; The Q-switching module includes a Q-switching crystal, a signal generator, an electro-optic driver, and electrodes. The Q-switching crystal is a lithium niobate crystal, and the Q-switching crystal is bonded to the second crystal.

2. The compact multi-wavelength laser as described in claim 1, characterized in that: The first crystal and the second crystal are lithium niobate crystals, and the first crystal and the second crystal are bonded together.

3. The compact multi-wavelength laser as described in claim 2, characterized in that: The first crystal is a scandium-doped lithium niobate crystal or a magnesium-doped lithium niobate crystal.

4. The compact multi-wavelength laser as described in claim 2, characterized in that: The second crystal is an Nd:MgO:LiNbO3 crystal.

5. The compact multi-wavelength laser as described in claim 4, characterized in that: The polarization period Λ of the second crystal is in the range of 7~9μm.

6. The compact multi-wavelength laser as described in claim 5, characterized in that: The temperature T of the second crystal is set according to the polarization period Λ.

7. The compact multi-wavelength laser as described in claim 6, characterized in that: The polarization period of the second crystal is Λ=7.9μm, and the temperature is T=27.1±0.1℃.

8. The compact multi-wavelength laser as described in claim 1, characterized in that: The resonant cavity is a confocal cavity.

9. The compact multi-wavelength laser as described in claim 1, characterized in that: The shaping module is a single lens or a group of lenses.

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