A 1.55μm band pulsed laser, its fabrication method and application

Abstract

This application discloses a 1.55μm band passively Q-switched pulsed laser, its fabrication method, and its application, belonging to the field of laser device technology. The 1.55μm band passively Q-switched pulsed laser includes a pump source, a laser cavity input mirror, a gain medium, a Q-switching element, and a laser cavity output mirror. This application uses Er... x Yb y R (1‑x‑y) M3(PO4)3 crystal, as the gain medium for passively Q-switched micropulse lasers in the 1.55μm band, is superior to the widely used Er... 3+ / Yb 3+ For double-doped phosphate glass, this crystal has higher thermal conductivity and longer upper-level fluorescence lifetime, enabling laser output with pulse energies in the hundreds of μJ and pulse widths in the nanoseconds.

Description

Technical Field

[0001] This application relates to a passively Q-switched pulsed laser in the 1.55μm band, its fabrication method and application, belonging to the field of laser device technology. Background Technology

[0002] The 1.55μm band laser, with its high atmospheric transmittance, strong smoke penetration capability, ease of detection, all-weather application, and high eye safety, will gradually replace the traditional 1.06μm band laser as the detection wavelength for next-generation eye-safe laser rangefinders and lidar. 3+ / Yb 3+ Double-doped phosphate glass is currently the only commercially available gain medium for 1.55μm band lasers. Therefore, domestic and international research institutions use it to obtain high-energy 1.55μm band solid-state pulsed microlasers with hundreds of μJ levels through passive Q-switching technology, and use it as the detection light source for eye-safe laser rangefinders. However, Er... 3+ / Yb 3+ Double-doped phosphate glass has a low thermal conductivity (approximately 0.8 W / m²). -1 K -1 The laser damage threshold and its inherent characteristics limit the performance and stability of pulsed lasers, increasing the design complexity of laser gain medium cooling schemes. Compared to laser glass, laser crystals generally possess superior mechanical and thermal properties, a higher laser damage threshold, and can achieve higher laser output power with more stable performance. 3+ / Yb 3+ Double-doped phosphate crystals not only possess high thermal conductivity (>2.0 W / m²), but also exhibit high thermal conductivity. -1 K -1 Furthermore, its spectral performance parameters related to laser operation in the 1.55μm band are the same as Er. 3+ / Yb 3+ Similar to double-doped phosphate glass, it also has a long fluorescence lifetime at the upper energy level of the laser, thus it is a new type of gain medium that can realize high-energy or simultaneously realize high-repetition-rate, high-energy and high-peak-power 1.55μm band pulsed laser operation. Summary of the Invention

[0003] One aspect of this application provides a 1.55μm band passively Q-switched pulsed laser, employing Er x Yb y R (1-x-y) M3(PO4)3 crystal, as the gain medium for passively Q-switched micropulse lasers in the 1.55μm band, is superior to the widely used Er... 3+ / Yb 3+For double-doped phosphate glass, this crystal exhibits higher thermal conductivity and a longer upper-level fluorescence lifetime. Combined with laser pump sources and other conditions, it can realize eye-safe 1.55μm band micro-pulsed lasers with pulse energies in the hundreds of μJ range. This addresses the issues of low thermal conductivity and laser damage threshold in the gain medium of existing lasers of this type, improving the performance and stability of the pulsed laser. Furthermore, this laser crystal can also be used to obtain eye-safe 1.55μm band micro-pulsed lasers with repetition rates in the kHz range, pulse energies in the hundreds of μJ range, and pulse widths in the nanoseconds range. This solves the problem that existing lidar detection sources in this band cannot simultaneously achieve high repetition rates and high peak power.

[0004] The passively Q-switched pulsed laser in the 1.55μm band described in this application includes a pump source, a laser cavity input mirror, a gain medium, a Q-switching element, and a laser cavity output mirror;

[0005] The pump source, laser cavity input mirror, gain medium, Q-switching element, and laser cavity output mirror are arranged coaxially along the optical path in sequence.

[0006] The gain medium is Er x Yb y R (1-x-y) M3(PO4)3 crystal;

[0007] Where x = 0.3–3.0 at.%, y = 5–50 at.%;

[0008] R is one or a combination of elements from Sc, Y, Gd, and Lu;

[0009] M is one or a combination of elements among Ca, Sr, and Ba;

[0010] The pump source adopts a pulse working mode, with a pump pulse period of 10 to 1000 ms and a pump pulse width of 1 to 10 ms;

[0011] The pump source is a semiconductor laser that generates laser light in the 976nm or 940nm band.

[0012] The end face of the laser cavity input mirror is coated with a laser cavity input mirror dielectric film;

[0013] The transmittance of the dielectric film of the laser cavity input mirror is higher than 90% in the 976nm or 940nm band, and lower than 0.5% in the 1.55μm band.

[0014] The end face of the laser cavity output mirror is coated with a laser cavity output mirror dielectric film.

[0015] The transmittance T of the dielectric film of the laser cavity output mirror is 2% to 30% in the 1.55μm band;

[0016] The Q-switching element includes Co. 2+ MgAl2O4 crystals;

[0017] The initial transmittance of the Q-switching element at the 1.55μm band is 80%–98%;

[0018] The waist spot diameter of the pump laser in the gain medium is 100-600 μm;

[0019] The peak incident pump power of the gain medium is 1-30W.

[0020] Optionally, the waist diameter of the pump laser in the gain medium is independently selected from any value of 100μm, 200μm, 300μm, 400μm, 500μm, 560μm, 600μm or a range between any two of the above.

[0021] Optionally, the peak incident pump power of the gain medium is independently selected from any one of 1W, 2W, 5W, 6W, 7W, 8W, 10W, 11W, 12W, 13W, 14W, 15W, 16W, 20W, 25W, 30W, or a range between any two of the above.

[0022] When 2% ≤ T < 10%, the peak incident pump power of the gain medium is 6-8W or 10-14W;

[0023] When 10% ≤ T ≤ 30%, the peak incident pump power of the gain medium is 9-11W or 15-17W.

[0024] The laser operates as a 1.55μm band single-pulse laser within a pump pulse width by controlling the incident pump power. The repetition frequency of the 1.55μm band pulse laser is modulated by the pump source to make the repetition frequency of the 1.55μm band pulse laser consistent with the repetition frequency of the pump source pulse, which is 1-100Hz. The laser can achieve 1.55μm band pulse laser output with a single pulse energy in the hundreds of μJ range.

[0025] By controlling the incident pump power, the laser can also achieve kHz-level high repetition rate 1.55μm band multi-pulse laser operation within a pump pulse width, and the laser can also achieve 1.55μm band pulse laser output with single pulse energy in the hundreds of μJ range.

[0026] Alternatively, x = 1.5-2.5 at.%.

[0027] Optionally, x is independently selected from any one of 0.3at.%, 1at.%, 1.5at.%, 1.6at.%, 1.7at.%, 1.8at.%, 1.9at.%, 2at.%, 2.5at.%, 3at.%, or a range between any two of the above.

[0028] Alternatively, y = 15-25 at.%.

[0029] Optionally, y is independently selected from any one of 5at.%, 10at.%, 15at.%, 16at.%, 17at.%, 20at.%, 24at.%, 25at.%, 30at.%, 40at.%, 50at.%, or a range between any two of the above.

[0030] Optionally, the pulsed laser further includes a focusing coupler disposed between the pump source and the laser input mirror, for focusing the emitted light from the pump source onto the gain medium. The gain medium is positioned near the focal point of the pump light, not exceeding the Rayleigh length range of the emitted beam from the pump source.

[0031] This application also provides a method for fabricating the 1.55μm band passively Q-switched pulsed laser, comprising: placing the laser cavity input mirror, gain medium, Q-switching element and laser cavity output mirror together coaxially along the optical path, and placing the pump source coaxially with the gain medium, Q-switching element and laser cavity output mirror.

[0032] Optionally, the gain medium and the Q-switching element are bonded together using an optical adhesive.

[0033] Optionally, the end face of the laser cavity input mirror is coated with a laser cavity input mirror dielectric film;

[0034] The transmittance of the dielectric film of the laser cavity input mirror is higher than 90% in the 976nm or 940nm band, and lower than 0.5% in the 1.55μm band.

[0035] Preferably, the transmittance of the dielectric film of the laser cavity input mirror is ≤0.1% at the 1.55μm wavelength band.

[0036] Optionally, the laser cavity input mirror dielectric film is directly deposited on the input end face of the gain medium, eliminating the need for a separate laser cavity input mirror.

[0037] Optionally, the end face of the laser cavity output mirror is coated with a laser cavity output mirror dielectric film;

[0038] The transmittance of the dielectric film of the laser cavity output mirror is 2% to 30% in the 1.55μm band;

[0039] Preferably, the transmittance of the dielectric film of the laser cavity output mirror is 5-15% in the 1.55μm band.

[0040] Optionally, the transmittance of the laser cavity output mirror dielectric film at the 1.55 μm band is independently selected from any one of 2%, 5%, 6%, 7%, 10%, 15%, 20%, 25%, 30%, or a range between any two of the above.

[0041] Optionally, the dielectric film of the laser cavity output mirror is directly deposited on the output end face of the Q-switching element, eliminating the need for a separate laser cavity output mirror;

[0042] Optionally, the laser cavity input mirror dielectric film is directly deposited on the input end face of the sapphire crystal, and then the output end face of the sapphire crystal is tightly bonded to the input end face of the gain medium. The coated sapphire crystal is directly used as the laser cavity input mirror.

[0043] Optionally, the output end face of the sapphire crystal and the input end face of the gain medium are bonded together using an optical adhesive method.

[0044] This application also provides an application of the aforementioned 1.55μm band passively Q-switched pulsed laser as a detection light source for laser rangefinders or lidar.

[0045] The beneficial effects that this invention can produce include:

[0046] (1) This application adopts Er x Yb y R (1-x-y) M3(PO4)3 crystal, as the gain medium for passively Q-switched micropulse lasers in the 1.55μm band, is superior to the widely used Er... 3+ / Yb 3+ For double-doped phosphate glass, this crystal has higher thermal conductivity and a longer fluorescence lifetime at the upper laser level. Combined with conditions such as laser pump source, it can achieve stable output of high-energy pulsed laser at the level of hundreds of μJ, and can reduce the design difficulty of gain medium cooling scheme.

[0047] (2) This application adopts Er x Yb y R (1-x-y) M3(PO4)3 crystal is used as the gain medium for passively Q-switched micropulse lasers in the 1.55μm band. This crystal has higher thermal conductivity, and when combined with the laser pump source and other conditions, it can achieve kHz-level high pulse repetition rates and improve the stability of the output laser. Using this high-energy, high-repetition-rate micropulse laser as the detection source for lidar not only enables the detection of distant targets but also achieves high scanning speeds and increases the amount of data received, thereby greatly improving the measurement accuracy of lidar and expanding its application range.

[0048] (3) This application adopts Er x Yb y R (1-x-y) M3(PO4)3 crystal, as the gain medium for passively Q-switched micro-pulse lasers in the 1.55μm band, can solve the problems of low thermal conductivity and laser damage threshold of the gain medium used in existing lasers of this type, thus improving the working performance and stability of pulsed lasers.

[0049] (4) Using this high-energy micro-pulse laser as the detection light source for laser rangefinders or lidar can improve the working performance and measurement accuracy of the instrument. Detailed Implementation

[0050] The present invention will now be described in detail with reference to the embodiments, but the present invention is not limited to these embodiments.

[0051] The detection method in the embodiments of this application is as follows: the pulsed laser energy is measured using a laser energy meter (probe model PE9-C, meter model Centauri, both products of Ophir-Spiricon); the pulsed laser repetition frequency and pulse width are detected using an oscilloscope (photodetector model DET08C of Thorlabs, oscilloscope model DSO6102A of Agilent); and the pulse peak power is the pulse energy divided by the pulse width.

[0052] Example 1

[0053] Example 1-1

[0054] 976nm semiconductor laser pump Er 0.016 Yb 0.176 Gd 0.808 A 1535nm micropulse laser with a repetition rate of 10Hz, a pulse energy of 140μJ, and a pulse width of 8.3ns was achieved using Sr3(PO4)3 crystal. Details are as follows:

[0055] Er 0.016 Yb 0.176 Gd 0.808 The Sr3(PO4)3 crystal was cut to have a light-transmitting cross section of 2×2mm. 2 A blocky sample with a thickness of 1.5 mm along the light transmission direction was laser-polished at its light-transmitting end face. The Q-switching element used was Co. 2+ MgAl2O4 crystal, with a light-transmitting cross section of 2×2mm. 2 The thickness along the light-transmitting direction is 1.4 mm, and the light-transmitting end face is laser-polished. This Q-switched crystal has an initial transmittance of 96% at the 1.55 μm wavelength. The dielectric film for the laser cavity input mirror is directly deposited on the light-transmitting cross-section, which is 2 × 2 mm.2 The input end face of a sapphire crystal with a thickness of 1.0 mm in the light transmission direction has a transmittance T≥90% for the dielectric film of the laser cavity input mirror at a wavelength of 976 nm and a transmittance T≤0.1% at a wavelength of 1.55 μm. The dielectric film of the laser cavity output mirror is deposited on a K9 glass surface with a radius of curvature of 200 mm, and the transmittance T=6.5% at a wavelength of 1.55 μm. The above sapphire crystal and Er... 0.016 Yb 0.176 Gd 0.808 Sr3(PO4)3 crystals and Co 2+ The MgAl2O4 crystals are bonded together and fixed to a copper base with a central light-transmitting aperture. The laser cavity output mirror is adjacent to the Co... 2+ The laser uses a MgAl2O4 crystal with a cavity length of 10 mm. The pump source is a 976 nm semiconductor laser operating in pulsed mode, with a pump pulse period of 100 ms and a pump pulse width of 4 ms. This pump laser is focused into the gain medium via a focusing coupling mirror, and the waist diameter of the pump laser in the gain medium is 560 μm. The Er... 0.016 Yb 0.176 Gd 0.808 A 1535nm micropulse laser with a repetition frequency of 10Hz, a pulse energy of 140μJ, a pulse width of 8.3ns, and a peak output power of 16.9kW was obtained by pumping a Sr3(PO4)3 crystal with a peak incident power of 8W.

[0056] Examples 1-2

[0057] 976nm semiconductor laser pump Er 0.016 Yb 0.176 Gd 0.808 A 1535nm micropulse laser with a repetition rate of 1.8kHz, a pulse energy of 160μJ, and a pulse width of 8.3ns was achieved using a Sr3(PO4)3 crystal, specifically the same as in Example 1-1, except that the Sr3(PO4)3 crystal was used to pump the Er35nm micropulse laser. 0.016 Yb 0.176 Gd 0.808 A 1535nm micropulse laser with a repetition rate of 1.8kHz, a pulse energy of 160μJ, a pulse width of 8.3ns, and a peak output power of 19.3kW was obtained by pumping a Sr3(PO4)3 crystal with a peak incident power of 14W.

[0058] Example 2

[0059] Example 2-1

[0060] 976nm semiconductor laser pump Er 0.016 Yb 0.176 Gd 0.808Sr3(PO4)3 crystals were used to achieve a 1535nm micropulse laser with a repetition rate of 10Hz, a pulse energy of 120μJ, and a pulse width of 8.0ns. Details are as follows:

[0061] The dielectric film of the laser cavity input mirror in Example 1-1 is directly deposited on Er 0.016 Yb 0.176 Gd 0.808 The input facet of a Sr3(PO4)3 crystal. This semiconductor laser facet is used to pump an Er... 0.016 Yb 0.176 Gd 0.808 A 1535nm micropulse laser with a repetition frequency of 10Hz, a pulse energy of 120μJ, a pulse width of 8.0ns, and a peak output power of 15.0kW was obtained by pumping a Sr3(PO4)3 crystal with a peak incident power of 7W.

[0062] Example 2-2

[0063] 976nm semiconductor laser pump Er 0.016 Yb 0.176 Gd 0.808 A 1535nm micropulse laser with a repetition rate of 1.7 kHz, a pulse energy of 135 μJ, and a pulse width of 8.0 ns was achieved using Sr3(PO4)3 crystal. Details are as follows:

[0064] The dielectric film of the laser cavity input mirror in Examples 1-2 was directly deposited on Er 0.016 Yb 0.176 Gd 0.808 The input facet of a Sr3(PO4)3 crystal. This semiconductor laser facet is used to pump an Er... 0.016 Yb 0.176 Gd 0.808 A 1535nm micropulse laser with a repetition rate of 1.7kHz, a pulse energy of 135μJ, a pulse width of 8.0ns, and a peak output power of 16.8kW was obtained by pumping a Sr3(PO4)3 crystal with a peak incident power of 13W.

[0065] Example 3

[0066] Example 3-1

[0067] 976nm semiconductor laser pump Er 0.016 Yb 0.176 Gd 0.808 A 1535nm micropulse laser with a repetition rate of 10Hz, a pulse energy of 110μJ, and a pulse width of 8.5ns was achieved using Sr3(PO4)3 crystal. Details are as follows:

[0068] The waist diameter of the pump laser in the gain medium in Example 1 was adjusted to 400 μm. Er was then pumped using this semiconductor laser endface. 0.016 Yb 0.176 Gd 0.808 A 1535nm micropulse laser with a repetition frequency of 10Hz, a pulse energy of 110μJ, a pulse width of 8.5ns, and a peak output power of 12.9kW was obtained by pumping a Sr3(PO4)3 crystal with a peak incident power of 6W.

[0069] Example 3-2

[0070] 976nm semiconductor laser pump Er 0.016 Yb 0.176 Gd 0.808 A 1535nm micropulse laser with a repetition rate of 2.24kHz, a pulse energy of 126μJ, and a pulse width of 8.5ns was achieved using Sr3(PO4)3 crystals.

[0071] Specifically as follows:

[0072] The waist diameter of the pump laser in the gain medium in Examples 1-2 was adjusted to 400 μm. This semiconductor laser endface was used to pump Er... 0.016 Yb 0.176 Gd 0.808 A 1535nm micropulse laser with a repetition rate of 2.1kHz, a pulse energy of 126μJ, a pulse width of 8.5ns, and a peak output power of 14.8kW was obtained by pumping a Sr3(PO4)3 crystal with a peak incident power of 10W.

[0073] Example 4

[0074] Example 4-1

[0075] 976nm semiconductor laser pump Er 0.016 Yb 0.176 Gd 0.808 A 1535nm micropulse laser with a repetition rate of 10Hz, a pulse energy of 230μJ, and a pulse width of 7.8ns was achieved using Sr3(PO4)3 crystal. Details are as follows:

[0076] Er 0.016 Yb 0.176 Gd 0.808 The Sr3(PO4)3 crystal was cut to have a light-transmitting cross section of 2×2mm. 2 A blocky sample with a thickness of 1.5 mm along the light transmission direction was subjected to laser-grade polishing on its light-transmitting end face. The Q-switching element used was Co. 2+ MgAl2O4 crystal, with a light-transmitting cross section of 2×2mm. 2The thickness along the light-transmitting direction is 1.6 mm, and the light-transmitting end face is laser-polished. This Q-switched crystal has an initial transmittance of 94% at the 1.55 μm wavelength. The dielectric film of the laser cavity input mirror is directly deposited on the light-transmitting cross-section of 2 × 2 mm. 2 The input end face of a sapphire crystal with a thickness of 1.0 mm in the light transmission direction has a transmittance T≥90% for the dielectric film of the laser cavity input mirror at a wavelength of 976 nm and a transmittance T≤0.1% at a wavelength of 1.55 μm. The dielectric film of the laser cavity output mirror is deposited on a K9 glass surface with a radius of curvature of 200 mm, and the transmittance T=15% at a wavelength of 1.55 μm. The above sapphire crystal and Er... 0.016 Yb 0.176 Gd 0.808 Sr3(PO4)3 crystals and Co 2+ The MgAl2O4 crystals are bonded together and fixed to a copper base with a central light-transmitting aperture. The laser cavity output mirror is adjacent to the Co... 2+ The laser uses a MgAl2O4 crystal with a cavity length of 10 mm. The pump source is a 976 nm semiconductor laser operating in pulsed mode, with a pump pulse period of 100 ms and a pump pulse width of 5 ms. This pump laser is focused into the gain medium via a focusing coupling mirror, and the waist diameter of the pump laser in the gain medium is 400 μm. The Er laser is pumped using the end face of this semiconductor laser. 0.016 Yb 0.176 Gd 0.808 A 1535nm micropulse laser with a repetition frequency of 10Hz, a pulse energy of 230μJ, a pulse width of 7.8ns, and a peak output power of 29.5kW was obtained by pumping a Sr3(PO4)3 crystal with a peak incident power of 11W.

[0077] Example 4-2

[0078] 976nm semiconductor laser pump Er 0.016 Yb 0.176 Gd 0.808 A 1535nm micropulse laser with a repetition rate of 1.5kHz, a pulse energy of 210μJ, and a pulse width of 7.8ns was achieved using Sr3(PO4)3 crystal. Specifically, the process is the same as in 4-1, except that the transmittance T = 10% of the output mirror dielectric film at the 1.55μm wavelength. This semiconductor laser end-face pumping method was then used to... 0.016 Yb 0.176 Gd 0.808 A 1535nm micropulse laser with a repetition frequency of 1.5kHz, a pulse energy of 210μJ, a pulse width of 7.8ns, and a peak output power of 26.9kW was obtained by pumping a Sr3(PO4)3 crystal with a peak incident power of 16W.

[0079] Example 5

[0080] Er 0.018 Yb 0.165 Y 0.817 Sr3(PO4)3 crystals replace Er in Examples 1-1, 1-2, 2-1, 2-2, 3-1, 3-2, 4-1, and 4-2 0.016 Yb 0.176 Gd 0.808 The experimental results for Sr3(PO4)3 crystals were similar to those in Examples 1-1, 1-2, 2-1, 2-2, 3-1, 3-2, 4-1, and 4-2.

[0081] Example 6

[0082] Er 0.019 Yb 0.24 Gd 0.741 Ba3(PO4)3 crystals replace Er in Examples 1-1, 1-2, 2-1, 2-2, 3-1, 3-2, 4-1, and 4-2 0.016 Yb 0.176 Gd 0.808 The experimental results for Sr3(PO4)3 crystals were similar to those in Examples 1-1, 1-2, 2-1, 2-2, 3-1, 3-2, 4-1, and 4-2.

[0083] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A passive modulation method in the 1.55μm band Q A pulsed laser, characterized in that, Including pump source, laser cavity input mirror, gain medium, and tuning Q Components and laser cavity output mirror; The pump source, laser cavity input mirror, gain medium, and modulation Q The components and the laser cavity output mirror are arranged coaxially along the optical path. The gain medium is Er x Yb y R (1-x-y) M3(PO4)3 crystal; Where x = 1.5~2.5 at.%, y = 15~25 at.%; R is one of the elements Sc, Y, Gd, and Lu; M is one of the elements Ca, Sr, and Ba; The pump source adopts a pulse working mode, with a pump pulse period of 10~1000ms and a pump pulse width of 1~10ms; The pump source is a semiconductor laser that generates laser light in the 976nm or 940nm band. The end face of the laser cavity input mirror is coated with a laser cavity input mirror dielectric film; The transmittance of the dielectric film of the laser cavity input mirror is higher than 90% in the 976nm or 940nm band, and lower than 0.5% in the 1.55μm band. The end face of the laser cavity output mirror is coated with a laser cavity output mirror dielectric film. The transmittance T of the dielectric film of the laser cavity output mirror is 2%~30% at the 1.55μm band; The adjustment Q Components include Co 2+ MgAl2O4 crystals; The adjustment Q The initial transmittance of the element at the 1.55μm band is 80%~98%; The waist diameter of the pump laser in the gain medium is 100~600μm; The peak incident pump power of the gain medium is 1~30W.

2. The 1.55μm band passive tuning according to claim 1 Q A pulsed laser, characterized in that, When 2%≤T<10%, the peak incident pump power of the gain medium is 6~8W or 10~14W; When 10%≤T≤30%, the peak incident pump power of the gain medium is 9~11W or 15~17W.

3. The 1.55μm band passive tuning according to claim 1 Q A pulsed laser, characterized in that, The pulsed laser also includes a focusing coupling mirror, which is disposed between the pump source and the laser cavity input mirror.

4. A passive modulation method for the 1.55μm band according to any one of claims 1-3 Q The method for fabricating a pulsed laser is characterized by, include: Laser cavity input mirror, gain medium, and tuning Q The components and the laser cavity output mirror are coaxially and tightly attached together along the optical path, and the pump source is connected to the gain medium and the tuning... Q The components and the laser cavity output mirror are placed coaxially.

5. The 1.55μm band passive tuning according to claim 4 Q The method for fabricating a pulsed laser is characterized by, The gain medium and modulation Q The components are bonded together using photoresist.

6. The 1.55μm band passive tuning according to claim 4 Q The method for fabricating a pulsed laser is characterized by, The laser cavity input mirror dielectric film is directly deposited on the input end face of the gain medium, eliminating the need for a separate laser cavity input mirror; The transmittance of the dielectric film of the laser cavity input mirror is higher than 90% in the 976nm or 940nm band, and lower than 0.5% in the 1.55μm band.

7. The 1.55μm band passive tuning according to claim 4 Q The method for fabricating a pulsed laser is characterized by, The laser cavity input mirror dielectric film is directly deposited on the input end face of the sapphire crystal, and then the output end face of the sapphire crystal is tightly attached to the input end face of the gain medium. The coated sapphire crystal is directly used as the laser cavity input mirror. The transmittance of the dielectric film of the laser cavity input mirror is higher than 90% in the 976nm or 940nm band, and lower than 0.5% in the 1.55μm band. The output end face of the sapphire crystal is bonded to the input end face of the gain medium using a photoresist method.

8. The 1.55μm band passive tuning according to claim 4 Q The method for fabricating a pulsed laser is characterized by, The dielectric film of the laser cavity output mirror is directly deposited on the modulation Q The output end face of the component does not require a separate laser cavity output mirror; The transmittance of the dielectric film of the laser cavity output mirror is 2% to 30% in the 1.55μm band.

9. A passive modulation method for the 1.55μm band as described in any one of claims 1-3 Q Applications of pulsed lasers as detection light sources in laser rangefinders or lidar.