Picosecond pulse source based on harmonic self-mode-locking semiconductor surface emitting laser

Abstract

The invention provides a picosecond pulse source based on a harmonic self-mode-locking semiconductor surface emitting laser, which comprises an optical pumping assembly and a V-cavity resonant cavity assembly, and is characterized in that the optical pumping assembly comprises a semiconductor bar laser and a collimating focusing lens optical coupling assembly, and the V-cavity resonant cavity assembly comprises a microcavity gain structure and an outer cavity structure; pump laser emitted by the semiconductor bar laser is focused and coupled through the collimating focusing lens optical coupling assembly, then light spots are output, the light spots are absorbed and gained through the microcavity gain structure, and resonance laser is output through feedback resonance of the outer cavity structure. And when the resonant laser in the external cavity structure is matched with the light spot, the external cavity structure outputs a mode-locked pulse after spatio-temporal dynamics calculation and adjustment. The picosecond pulse source realizes harmonic mode-locked pulse output with hundred picosecond pulse width and hundred MHz repetition frequency.

Description

Technical Field

[0001] The invention relates to the technical field of picosecond pulse lasers, and in particular to a picosecond pulse source based on a harmonic self-mode-locked semiconductor surface emitting laser. Background Art

[0002] Compared with nanosecond pulse lasers, picosecond pulse lasers have the advantages of small heat-affected zone, fast processing speed and high processing quality in the field of laser processing. They also have wide commercial applications in signal processing, material processing and free space communications. High-power picosecond pulse lasers used in industry usually require single pulse energies of up to microjoules or even subjoules. These systems use mode-locked seed lasers, single pulse selection and multi-stage amplification to achieve high single pulse energy output in the range of hundreds of picoseconds. The mode-locked picosecond pulse source used is a key component of the picosecond pulse laser, which usually operates at a repetition rate of several hundred MHz with a pulse width of several hundred picoseconds.

[0003] At present, picosecond pulse lasers mainly include mode-locked solid lasers, mode-locked fiber lasers, and mode-locked semiconductor lasers. Among them, solid pulse seed laser sources have problems such as limited emission wavelength, complex structure, high cost, and poor stability. Mode-locked fiber lasers have a limited wavelength range, rely on saturable absorber mirrors or ring cavity structures, and due to the limitation of fiber length, the repetition frequency is usually limited to kilohertz. In contrast, mode-locked semiconductor lasers have received great attention in the research of picosecond pulse sources. They have many advantages, including wavelength flexibility, compact size, long service life, and low cost. When used in combination with an appropriate external cavity, that is, a mode-locked vertical external cavity surface emitting laser (VECSEL), the output pulse characteristics can be more easily manipulated to achieve the desired performance results, such as beam quality close to the diffraction limit, high output power, and arbitrary radiation wavelength. More importantly, VECSEL is able to generate self-mode-locked (SML) pulses without the participation of SESAM. Unlike fiber-seeded laser sources and solid-state mode-locked picosecond pulse sources, it does not require the participation of a saturable absorber, thus eliminating the need for specific design of the saturable absorber, such as the output wavelength, saturation flux, and modulation depth. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the above-mentioned shortcomings, the main purpose of the present invention is to provide a picosecond pulse source based on a harmonic self-mode-locked semiconductor surface emitting laser, which solves the shortcomings of the solid pulse seed source, such as limited wavelength, complex structure, high cost and stability, as well as the MHz repetition frequency limited by the length of the optical fiber seed source, narrow wavelength selection range and the need for the participation of a complexly designed saturable absorber, and obtains the output of pulses with a pulse width of hundreds of picoseconds and a pulse width of hundreds of MHz.

[0006] (II) Technical solution

[0007] In order to achieve the above-mentioned object, the present invention provides a picosecond pulse source based on a harmonic self-mode-locked semiconductor surface emitting laser, comprising an optical pumping component and a V-cavity resonant cavity component, wherein the optical pumping component comprises a semiconductor bar laser and a collimating focusing lens optical coupling component, and the V-cavity resonant cavity component comprises a microcavity gain structure and an external cavity structure; wherein the pump laser emitted by the semiconductor bar laser is focused and coupled by the collimating focusing lens optical coupling component to output a light spot, the light spot is absorbed and gain-processed by the microcavity gain structure, and then the resonant laser is output through feedback resonance of the external cavity structure; and when the resonant laser in the external cavity structure matches the light spot, the external cavity structure is adjusted by spatiotemporal dynamics calculation to output a mode-locked pulse.

[0008] In the above scheme, the microcavity gain structure includes a semiconductor gain chip, a heat sink and an air interface on the surface of the semiconductor gain chip; wherein the semiconductor gain chip is bonded to the heat sink by Au-In solid-liquid diffusion.

[0009] In the above scheme, the semiconductor gain chip includes a substrate, a barrier layer, a bottom DBR reflector, an active region multi-quantum well layer and a surface cap layer stacked in sequence from bottom to top along a first direction; wherein, after the substrate and the barrier layer are removed, the semiconductor gain chip is bonded to the heat sink through Au-In solid-liquid diffusion bonding.

[0010] In the above scheme, the absorption wavelength range of the quantum wells in the multi-quantum well layer in the active region covers the pump laser.

[0011] In the above scheme, the material of the bottom DBR reflector is lattice matched with the material of the substrate; and the bottom DBR reflector is obtained by alternating the growth of two materials whose refractive index difference exceeds a preset refractive index threshold; and the central wavelength of the bottom DBR reflector is consistent with the design wavelength of the active region.

[0012] In the above scheme, the microcavity gain structure is a resonant periodic gain structure, and the standing wave antinode of the microcavity gain structure should be located above the multi-quantum well layer in the active region of the semiconductor gain chip for gain maximization processing.

[0013] In the above scheme, the external cavity structure is a laser resonant cavity, including a bottom DBR reflector, a first reflector and a second reflector; wherein the first reflector is a coupling mirror with a curvature radius, and the reflectivity of the first reflector is higher than a preset reflectivity threshold; the second reflector is a plane output mirror.

[0014] In the above solution, the first reflector is used to control the matching between the resonant laser and the light spot in the external cavity structure.

[0015] In the above scheme, after the calculation and adjustment of the spatiotemporal dynamics of the external cavity structure, the electric field strength of all locked transverse electromagnetic modes is obtained; and by controlling the external cavity structure, the mode locking consistent with the spatiotemporal dynamics calculation is obtained to achieve the output of the mode-locked pulse.

[0016] In the above scheme, when the round-trip time of the resonant laser through the external cavity structure is greater than or equal to twice the carrier lifetime of the semiconductor gain chip, the external cavity structure outputs harmonic mode locking.

[0017] (III) Beneficial effects

[0018] The technical solution of the embodiment of the present invention has at least the following beneficial effects:

[0019] (1) This picosecond pulse source based on harmonic self-mode-locked semiconductor surface-emitting laser has flexible emission wavelength, high beam quality, long service life and low generation cost.

[0020] (2) This picosecond pulse source based on harmonic self-mode-locked semiconductor surface emitting laser takes advantage of the advantages of semiconductor laser materials and achieves picosecond pulse output through self-locking. It has the characteristics of stability and reliability, simple technical structure, and no inserted components in the cavity.

[0021] (3) The picosecond pulse source based on harmonic self-mode-locked semiconductor surface emitting laser has a flexible external cavity structure, which facilitates the flexible design of its pulse repetition frequency according to needs and meets a wider range of application requirements.

[0022] (4) The external cavity structure of the picosecond pulse source based on the harmonic self-mode-locked semiconductor surface emitting laser is also convenient for inserting other optical elements, such as nonlinear frequency conversion elements, to achieve frequency conversion and obtain self-mode-locked picosecond pulse output of other wavelengths and high beam quality fundamental transverse mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The overall structure of a picosecond pulse source based on a harmonic self-mode-locked semiconductor surface emitting laser according to an embodiment of the present invention is schematically shown;

[0024] Figure 2 A schematic diagram showing the structure of an optical pumping component of a picosecond pulse source based on a harmonic self-mode-locked semiconductor surface emitting laser according to an embodiment of the present invention;

[0025] Figure 3 A schematic diagram of the structure of a semiconductor gain chip of a picosecond pulse source based on a harmonic self-mode-locked semiconductor surface emitting laser according to an embodiment of the present invention is shown;

[0026] Figure 4A schematic diagram of the structure of a semiconductor gain chip after thermal management of a picosecond pulse source based on a harmonic self-mode-locked semiconductor surface emitting laser according to an embodiment of the present invention is shown;

[0027] Figure 5 A diagram schematically shows a pulse sequence result of a picosecond pulse source based on a harmonic self-mode-locked semiconductor surface emitting laser according to an embodiment of the present invention;

[0028] Figure 6 The figure schematically shows the pulse width result of the pulse source based on the harmonic self-mode-locked semiconductor surface emitting laser according to the embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0030] Figure 1 The overall structure of a picosecond pulse source based on a harmonic self-mode-locked semiconductor surface emitting laser according to an embodiment of the present invention is schematically shown. Figure 2 The structure of an optical pumping component of a picosecond pulse source based on a harmonic self-mode-locked semiconductor surface emitting laser according to an embodiment of the present invention is schematically shown.

[0031] like Figure 1 As shown, the picosecond pulse source based on harmonic self-mode-locked semiconductor surface emitting laser includes an optical pumping component 1 and a V-cavity resonant cavity component 2, wherein the optical pumping component 1 includes a semiconductor bar laser 11 and a collimating focusing lens optical coupling component 12, and the V-cavity resonant cavity component 2 includes a microcavity gain structure 21 and an external cavity structure 22; wherein the pump laser emitted by the semiconductor bar laser 11 is focused and coupled by the collimating focusing lens optical coupling component 12 to output a light spot, the light spot is absorbed and gain-processed by the microcavity gain structure 21, and then feedback resonates and outputs a resonant laser through the external cavity structure 22; and when the resonant laser in the external cavity structure 22 matches the light spot, the external cavity structure 22 outputs a mode-locked pulse after being adjusted by spatiotemporal dynamics calculation.

[0032] Specifically, if Figure 2 As shown, the optical pumping component 1 includes a semiconductor bar laser 11 and a collimating focusing lens optical coupling component 12. For example, the pumping laser wavelength output by the semiconductor bar laser 11 is 808 nm, the output power is 50W, wherein the laser fiber core diameter is 200μm, and the numerical aperture is 0.22. The collimating focusing lens optical coupling component 12 performs 1:3 optical coupling system focusing on the pumping laser outputted from the laser fiber, and the focused spot diameter is 600μm.

[0033] Figure 3The structure of a semiconductor gain chip of a picosecond pulse source based on a harmonic self-mode-locked semiconductor surface emitting laser according to an embodiment of the present invention is schematically shown. Figure 4 The structure of a semiconductor gain chip after thermal management of a picosecond pulse source based on a harmonic self-mode-locked semiconductor surface emitting laser according to an embodiment of the present invention is schematically shown.

[0034] In an embodiment of the present invention, Figure 1 As shown, the microcavity gain structure 21 includes a semiconductor gain chip 211, a heat sink 212 and an air interface on the surface of the semiconductor gain chip 211; wherein the semiconductor gain chip 211 is bonded to the heat sink 212 by Au-In solid-liquid diffusion bonding.

[0035] Further, such as Figure 3 As shown, the semiconductor gain chip 211 includes a substrate 35, a barrier layer 34, a bottom DBR reflector 33, an active region multi-quantum well layer 32 and a surface cap layer 31 which are sequentially stacked from bottom to top along a first direction X1.

[0036] Specifically, the semiconductor gain chip 211 is grown by metal organic chemical vapor deposition MOCVD, and the barrier layer 34, the bottom DBR reflector 33, the active region multi-quantum well layer 32 and the surface cap layer 31 are sequentially etched from bottom to top along the first direction X1 on the substrate 35.

[0037] Preferably, the semiconductor gain chip 211 is made of III-V semiconductor material.

[0038] Preferably, the substrate 35 is made of GaAs material, and the barrier layer 34 is made of InGaP material.

[0039] In the embodiment of the present invention, after the substrate 35 and the barrier layer 34 are removed, the semiconductor gain chip 211 is bonded to the heat sink 212 by Au—In solid-liquid diffusion bonding.

[0040] Specifically, the semiconductor gain chip 211 is subjected to substrate 35 and barrier layer 34 removal and heat dissipation treatment. First, the substrate 35 of the semiconductor gain chip 211 is removed by chemical wet etching. The preferred etching solution is a solution of ammonia water and hydrogen peroxide in proportion, which can quickly etch, shorten the etching time, and improve the flatness of the etching. After the substrate 35 is removed by etching, the etching barrier layer 34 is then removed. Figure 4 As shown, the semiconductor gain chip 211 after the substrate 35 and the barrier layer 34 are removed is bonded to the heat sink 212 by Au-In solid-liquid diffusion, that is, the bottom DBR reflector 33 is bonded to the heat sink 212 by Au-In solid-liquid diffusion.

[0041] Preferably, the heat sink 212 is made of a material with high thermal conductivity and a heat sink surface roughness as low as possible <0.2 nm. For example, the heat sink 212 material may be a copper heat sink with high flatness.

[0042] In an embodiment of the present invention, the material of the bottom DBR reflector 33 is lattice matched with the material of the substrate 35; and the bottom DBR reflector 33 is obtained by alternating the growth of two materials whose refractive index difference exceeds a preset refractive index threshold; and the central wavelength of the bottom DBR reflector 33 is consistent with the design wavelength of the active region.

[0043] Specifically, the center wavelength of the bottom DBR reflector 33 is consistent with the design wavelength of the active region, the reflection bandwidth should be as wide as possible>100 nm, and the reflectivity should be as high as possible>99.9%. The bottom DBR reflector 33 should be obtained by alternating the growth of two materials with a large refractive index difference and a lattice match with the GaAs substrate, preferably GaAs / AlGaAs material.

[0044] For example, the central wavelength of the bottom DBR reflector 33 is 1064 nm, the reflection bandwidth is 100 nm, and it is a periodic structure formed by alternating growth of two materials, GaAs and AlGaAs. The number of pairs of the periodic structure of the bottom DBR reflector 33 is 27.5 pairs.

[0045] In the embodiment of the present invention, the absorption wavelength range of the quantum wells in the active region multi-quantum well layer 32 covers the pump laser.

[0046] For example, the wavelength of the pump laser and the absorption wavelength of the quantum well in the active region multi-quantum well layer 32 may be consistent, both being 808 nm.

[0047] Preferably, the active region multi-quantum well layer 32 is a "sandwich" structure of InGaAs / GaAs / GaAsP materials. For example, the active region multi-quantum well layer 32 structure is composed of 11 pairs of InGaAs / GaAs material quantum wells, and the barrier layer material can be GaAsP; the central wavelength of the active region multi-quantum well layer 32 structure is 1064 nm, and its optical thickness is half of the central wavelength.

[0048] Exemplarily, the surface cap layer 31 is a high potential barrier layer, which prevents carriers from leaking to the surface of the gain chip and causing non-radiative recombination, and plays a protective role. Preferably, the surface cap layer 31 can be made of GaAs material.

[0049] In the embodiment of the present invention, the pump laser emitted by the semiconductor bar laser 11 is focused and coupled by the collimating focusing lens optical coupling component 12 to output a light spot, and the light spot is absorbed and amplified by the microcavity gain structure 21, and then feedback resonates through the external cavity structure 22 to output a resonant laser.

[0050] Please continue reading Figure 1 In an embodiment of the present invention, the microcavity gain structure 21 is a resonant periodic gain structure, and the standing wave antinode of the microcavity gain structure 21 should be located above the active region multi-quantum well layer 32 of the semiconductor gain chip 211 for gain maximization processing.

[0051] Exemplarily, the microcavity gain structure 21 is a resonant periodic gain structure, and the standing wave antinode of the microcavity gain structure 21 should be located directly above the multi-quantum well layer 32 in the active region of the gain chip to maximize the gain of the light spot.

[0052] like Figure 1 As shown, the external cavity structure 22 is V-shaped, and the external cavity structure 22 is a laser resonant cavity, including a bottom DBR reflector 33, a first reflector 221, a second reflector 222, and the distances between the bottom DBR reflector 33, the first reflector 221, and the second reflector 222; wherein the first reflector 221 is a coupling mirror with a curvature radius, and the reflectivity of the first reflector 221 is higher than a preset reflectivity threshold; the second reflector 222 is a plane output mirror.

[0053] In the embodiment of the present invention, the first reflector 221 is used to control the matching between the resonant laser and the light spot in the external cavity structure 22 .

[0054] Exemplarily, the first reflector 221 is a high reflectivity coupling mirror with a curvature radius of R>99.9%, and the curvature radius R=1000 mm, which is used to control the matching of the resonant laser and the light spot in the external cavity structure 22 .

[0055] Exemplarily, the second reflector 222 is a plane output mirror with a transmittance T=0.6%.

[0056] In the embodiment of the present invention, when the resonant laser in the external cavity structure 22 matches the light spot, the external cavity structure 22 outputs a mode-locked pulse after being adjusted by spatiotemporal dynamics calculation.

[0057] Figure 5 The figure schematically shows the pulse sequence result of a picosecond pulse source based on a harmonic self-mode-locked semiconductor surface emitting laser according to an embodiment of the present invention. Figure 6 The figure schematically shows the pulse width result of the pulse source based on the harmonic self-mode-locked semiconductor surface emitting laser according to the embodiment of the present invention.

[0058] It can be understood that after the calculation and adjustment of the space-time dynamics of the external cavity structure 22, the electric field strength of all locked transverse electromagnetic modes is obtained; and by controlling the external cavity structure 22, the mode locking consistent with the space-time dynamics calculation is obtained to achieve the output of the mode-locked pulse.

[0059] For example, the repetition frequency corresponding to the length of the external cavity structure 22 is 80 MHz, and the beam waist of the light beam on the surface of the gain chip is calculated by using the ABCD transmission matrix to be 346 μm in the sagittal plane and 401 μm in the tangential plane. By calculating the spatiotemporal dynamics of the external cavity structure, all TEM lmn The electric field strength for transverse electromagnetic mode locking.

[0060] Furthermore, when the round trip time of the resonant laser through the external cavity structure 22 is greater than or equal to twice the carrier lifetime of the semiconductor gain chip 211 , the external cavity structure 22 outputs harmonic mode locking.

[0061] It is understandable that when the round trip time of the resonant laser through the external cavity structure 22 is much longer than the carrier lifetime of the gain chip, harmonic mode locking can be achieved. Preferably, the round trip time of the resonant laser through the external cavity structure 22 is about 3 to 4 times the carrier lifetime of the gain chip.

[0062] In this way, the effect of the coupling coefficient of the high-order transverse mode on promoting the stability of the locked mode can be obtained by calculation, and the coupling coefficient of the high-order transverse mode and the corresponding cavity structure when the locked mode is stable can be determined. For example, the relationship between the transverse modes of each order is calculated to be 1*TEM 00 +0.5*TEM 01 +0.1*TEM 02 When , a stable harmonic mode-locked pulse output is obtained. Figure 5 As shown in FIG. 1 , by using a photodiode to measure the pulse sequence of the picosecond pulse source, the mode-locked repetition frequency is 340 MHz, which is 4 times the resonant cavity structure frequency, i.e., the external cavity structure frequency. Figure 6 As shown, the pulse width of the pulse source is 352ps.

[0063] Through the embodiment of the present invention, the picosecond pulse source based on the harmonic self-locking mode semiconductor surface emitting laser realizes a wavelength of 1064 nm, a pulse repetition frequency of 340 MHz, and a pulse width of 352 ps by combining the gain chip with multiple external passive optical elements into a resonant cavity self-locking mode. In addition, the picosecond pulse source based on the harmonic self-locking mode semiconductor surface emitting laser achieves a pulse output with a pulse width of hundreds of ps and a repetition frequency of hundreds of MHz by fine-tuning the coupling coefficient of the high-order transverse mode in the external cavity structure 22, does not require the participation of other nonlinear elements such as SESAM, does not need to be limited by the bandwidth limitation of SESAM, and has the characteristics of simple structure.

[0064] It should be noted that the picosecond pulse source based on harmonic self-mode-locked semiconductor surface emitting laser can also be coordinated with other experiments, for example, combined with frequency-doubled VECSEL, pulse sources of other wavelengths can be obtained on the basis of the device. It can be seen that the external cavity structure of the picosecond pulse source based on harmonic self-mode-locked semiconductor surface emitting laser is also convenient for inserting other optical elements to achieve frequency conversion and obtain self-mode-locked picosecond pulse output of other wavelengths and beam quality TEM00.

[0065] Through the embodiments of the present invention, the picosecond pulse source based on the harmonic self-mode-locked semiconductor surface emitting laser can be set to match the size of the pump spot incident on the gain chip by calculating the spatiotemporal dynamics of the external cavity structure, control the mode existing in the resonant cavity structure, and promote the self-mode-locked stability of the semiconductor surface emitting laser in combination with the nonlinear Kerr effect determined by the semiconductor material inside the gain chip, so as to achieve the harmonic mode-locked pulse output with a pulse width of 100 picoseconds and a repetition frequency of 100 MHz, thereby solving the difficulty of the fiber laser in achieving a kilohertz repetition rate. In addition, the picosecond pulse source based on the harmonic self-mode-locked semiconductor surface emitting laser has good practicality and operability, compact structure, suitable for repeated production and assembly, suitable for mass production, low cost, unidirectional laser output, high repetition frequency, high stability and high beam quality.

[0066] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A picosecond pulse source based on harmonic self-mode-locked semiconductor surface emitting laser, characterized in that: It comprises an optical pumping component (1) and a V-cavity resonant cavity component (2), wherein the optical pumping component (1) comprises a semiconductor bar laser (11) and a collimating focusing lens optical coupling component (12), and the V-cavity resonant cavity component (2) comprises a microcavity gain structure (21) and an external cavity structure (22); The pump laser emitted by the semiconductor bar laser (11) is focused and coupled by the collimating focusing lens optical coupling component (12) to output a light spot, and the light spot is absorbed and amplified by the microcavity gain structure (21), and then feedback resonates through the external cavity structure (22) to output a resonant laser; and When the resonant laser matches the light spot in the external cavity structure (22), the external cavity structure (22) outputs a mode-locked pulse after being adjusted by spatiotemporal dynamics calculation.

2. The picosecond pulse source based on harmonic self-mode-locked semiconductor surface emitting laser according to claim 1, characterized in that: The microcavity gain structure (21) comprises a semiconductor gain chip (211), a heat sink (212) and an air interface on the surface of the semiconductor gain chip (211); The semiconductor gain chip (211) is bonded to the heat sink (212) by Au-In solid-liquid diffusion bonding.

3. The picosecond pulse source based on harmonic self-mode-locked semiconductor surface emitting laser according to claim 1 or 2, characterized in that: The semiconductor gain chip (211) comprises a substrate (35), a barrier layer (34), a bottom DBR reflector (33), an active region multi-quantum well layer (32), and a surface cap layer (31) which are stacked in sequence from bottom to top along a first direction; The semiconductor gain chip (211) is bonded to the heat sink (212) through Au-In solid-liquid diffusion bonding after the substrate (35) and the barrier layer (34) are removed.

4. The picosecond pulse source based on harmonic self-mode-locked semiconductor surface emitting laser according to claim 3, characterized in that: The absorption wavelength range of the quantum wells in the active region multi-quantum well layer (32) covers the pump laser.

5. The picosecond pulse source based on harmonic self-mode-locked semiconductor surface emitting laser according to claim 3, characterized in that: The material of the bottom DBR reflector (33) is lattice matched to the material of the substrate (35); and The bottom DBR reflector (33) is obtained by alternately growing two materials whose refractive index difference exceeds a preset refractive index threshold; The central wavelength of the bottom DBR reflector (33) is consistent with the design wavelength of the active region.

6. The picosecond pulse source based on harmonic self-mode-locked semiconductor surface emitting laser according to claim 3, characterized in that: The microcavity gain structure (21) is a resonant periodic gain structure, and the standing wave antinode of the microcavity gain structure (21) should be located above the active region multi-quantum well layer (32) of the semiconductor gain chip (211) for gain maximization processing.

7. The picosecond pulse source based on harmonic self-mode-locked semiconductor surface emitting laser according to claim 3, characterized in that: The external cavity structure (22) is a laser resonant cavity, comprising a bottom DBR reflector (33), a first reflector (221) and a second reflector (222); Wherein, the first reflector (221) is a coupling mirror having a curvature radius, and the reflectivity of the first reflector (221) is higher than a preset reflectivity threshold; The second reflector (222) is a plane output mirror.

8. The picosecond pulse source based on harmonic self-mode-locked semiconductor surface emitting laser according to claim 1 or 7, characterized in that: The first reflecting mirror (221) is used to control the matching of the resonant laser and the light spot in the external cavity structure (22).

9. The picosecond pulse source based on harmonic self-mode-locked semiconductor surface emitting laser according to claim 1, characterized in that: After the calculation and adjustment of the spatiotemporal dynamics of the external cavity structure (22), the electric field strength of all locked transverse electromagnetic modes is obtained; as well as By controlling the external cavity structure (22), mode locking consistent with aerodynamic calculations is obtained, thereby achieving output of mode-locked pulses.

10. The picosecond pulse source based on harmonic self-mode-locked semiconductor surface emitting laser according to claim 1 or 9, characterized in that: When the round trip time of the resonant laser through the external cavity structure (22) is greater than or equal to twice the carrier lifetime of the semiconductor gain chip (211), the external cavity structure (22) outputs harmonic mode locking.

Images