CN114374141B - 1.55 mu m pulse laser and application thereof - Google Patents

Abstract

The present application discloses a 1.55 μm band pulsed laser, which adopts (Er _x Yb _y Lu _(1-x-y) ) ₂ Si ₂ O ₇ crystal as the gain medium, where x=0.3-2.0 at.%, y = 3-20 at.%. The present application also discloses a light source of a laser rangefinder, which is the 1.55 μm pulsed laser. The eye-safe 1.55μm-band micro-pulse laser has hundreds of hertz-level repetition frequency, hundred-microjoule-level pulse energy and nanosecond-level pulse width, which can solve the problem of low pulse repetition frequency of the detection beam of the existing laser rangefinder in this band.

Description

A 1.55μm Pulse Laser and Its Application

technical field

The application relates to a pulsed laser and its application, in particular to an eye-safe 1.55 μm band high-energy miniature pulsed laser, which belongs to the technical field of laser devices.

Background technique

The eye-safe 1.55μm band laser range finder is widely used in remote sensing, surveying and military fields. The laser rangefinder needs a miniaturized, low-cost and stable 1.55μm-band solid-state pulsed laser to output a detection beam. In order to accurately measure targets within a distance of several kilometers, pulsed lasers should have high pulse energy on the order of hundreds of microjoules, narrow pulse width on the order of nanoseconds, and good beam quality. At present, using erbium-ytterbium double-doped phosphate glass as the gain medium can realize passive Q-switched micro-pulse laser with energy above 100 microjoules and width of several nanoseconds, and is widely used as the detection beam of the 1.55 μm band laser rangefinder . However, due to the serious thermal effect caused by the low thermal conductivity of phosphate glass (about 0.8Wm ^-1 K ^-1 ), the pulse repetition frequency of Erbium-Ytterbium double-doped phosphate glass laser is generally low when working at high pulse energy. A high repetition rate can achieve high scanning speed and increase the data volume of the received signal, thereby greatly improving the measurement accuracy of the range finder and expanding its application range. Therefore, it is necessary to develop a high-energy 1.55 μm micro-pulse laser that can work at a repetition rate of 100 Hz for laser rangefinders.

Erbium-ytterbium double-doped Lu ₂ Si ₂ O ₇ crystal has high thermal conductivity (about 9-14Wm ^-1 K ^-1 ) and long laser upper level fluorescence lifetime (8-9ms), and Yb ³⁺ in the crystal → The energy transfer efficiency of Er ³⁺ can reach 85%, so the crystal is a high-performance gain medium that can realize high-energy 1.55μm pulsed laser operation.

Contents of the invention

This application provides an eye-safe 1.55 μm band micro-pulse laser with a repetition rate of hundreds of hertz, a pulse energy of a hundred microjoules, and a pulse width of nanoseconds, which can solve the problem of pulse repetition of the detection beam of the existing laser rangefinder in this band. low frequency problem.

According to one aspect of the present application, a 1.55 μm pulsed laser is provided.

A 1.55 μm pulsed laser, wherein the 1.55 μm pulsed laser includes a pump source, an input mirror dielectric film, a gain medium, a Q-switching element, and an output mirror dielectric film along a coaxial axis;

The transmittance of the input mirror dielectric film in the 976nm and/or 905nm band is set to ≥90%, and the transmittance in the 1.55μm band is set to ≤0.5%;

The initial transmittance of the Q-switching element in the 1.55 μm band is set to 70-95%;

The transmittance of the output mirror dielectric film in the 1.55 μm band is set to 10-40%;

The working mode of the pump source is a pulse working mode, the pulse period of the pulse working mode is 2-100ms, and the pulse width is 0.2-10ms;

The pump source can generate laser light in the 976nm and/or 905nm band.

The laser realizes 1.55 μm band single pulse laser operation within a pump pulse width by controlling the incident pump power, and the repetition frequency of the 1.55 μm band pulse laser is modulated by the pump source so that the repetition frequency of the 1.55 μm band pulse laser is the same as The pulse repetition frequency of the pump source is the same.

Optionally, the gain medium includes erbium-ytterbium co-doped lutetium pyrosilicate crystal;

The chemical formula of the erbium-ytterbium co-doped lutetium pyrosilicate crystal is (Er _x Yb _y Lu _(1-xy) ) ₂ Si ₂ O ₇ , where x=0.3-2.0 at.%, y=3-20 at.%, x=0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0at.% Any value or any two values Any value in the range of y=3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20at.% Any value or any value in a range of any two numbers.

Optionally, the Q-switching element includes Co ²⁺ :MgAl ₂ O ₄ crystals.

Optionally, the input mirror dielectric film is coated on the input end face of the gain medium;

The output mirror dielectric film is coated on the output end face of the Q-switching element;

The output end face of the gain medium and the input end face of the Q-switching element are combined by optical glue.

Optionally, a focusing coupling mirror is provided between the pump source and the dielectric film of the input mirror.

Optionally, there is a sapphire crystal between the input mirror dielectric film and the gain medium, the input mirror dielectric film is plated on the input end face of the sapphire crystal, and the output end face of the sapphire crystal and the input end face of the gain medium are bonded by optical glue.

The second aspect of the present application provides a light source for a laser range finder.

The light source of the laser rangefinder is the above-mentioned 1.55 μm pulsed laser.

The beneficial effect that this application can produce comprises:

The present invention adopts (Er _{x Yby} Lu _(1-xy) ) ₂ Si ₂ O ₇ crystal as the gain medium of the 1.55 μm band micro-pulse laser. Compared with the erbium-ytterbium double-doped phosphate glass widely used at present, the crystal has higher thermal conductivity, can achieve higher pulse repetition frequency and improve the stability of the output laser. At the same time, the crystal also has a long laser upper level fluorescence lifetime, which can realize high-energy pulsed laser output. Using this high-energy micro-pulse laser as the detection light source of the laser rangefinder can not only detect long-distance targets, but also achieve high scanning speed and increase the data volume of the received signal, thereby greatly improving the rangefinder. Measure accuracy and expand its range of applications.

Detailed ways

The present application is described in detail below in conjunction with the examples, but the present application is not limited to these examples.

Detection method in the embodiment of the present application is as follows: pulsed laser energy adopts laser energy meter (probe model PE9-C, gauge model is Centauri, is Ophir-Spiricon company product) measurement; Pulsed laser repetition frequency and pulse width adopt oscilloscope ( The model of the photodetector is DET08C of Thorlabs Company, and the model of the oscilloscope is DSO6102A of Agilent Company.

Cut the (Er _x Yb _y Lu _1-xy ) ₂ Si ₂ O ₇ crystal into a Y-cut block sample with a light-passing section of 3×3mm ² and a thickness of 3.0mm in the light-passing direction. Optical end faces are laser grade polished. The Q-switching element adopts Co ²⁺ :MgAl ₂ O ₄ crystal, the light-passing section is 3×3mm ² , the thickness in the light-passing direction is 1.5mm, and the light-passing end surface is laser-level polished. The initial The transmittance is 90%. The dielectric film of the input mirror is directly coated on the input end face of (Er _x Yb _y Lu _1-xy ) ₂ Si ₂ O ₇ crystal. Rate T≤0.1%. The dielectric film of the output mirror is directly plated on the output end face of the Co ²⁺ :MgAl ₂ O ₄ crystal, and the transmittance of the dielectric film of the output mirror is T=15% at the 1.55 μm wave band. The above-mentioned (Er _x Yb _y Lu _1-xy ) ₂ Si ₂ O ₇ crystal output end face and Co ²⁺ :MgAl ₂ O ₄ crystal input end face are closely bonded together by optical glue, and then fixed on the copper with a light hole in the middle seat.

Example 1

The pump source adopts a 976nm semiconductor laser in pulse mode, the pump pulse period is 10ms, and the pump pulse width is 2ms. The pump laser is focused into the gain medium through the focusing coupling mirror. The waist spot diameter of the pump laser in the gain medium is is 300 μm. Using the semiconductor laser end-pumped (Er _0.005 Yb _0.05 Lu _0.945 ) ₂ Si ₂ O ₇ crystal, under 20W peak incident power pumping, a 1.55μm band micro pulse with 100Hz repetition frequency, 120μJ pulse energy and 2.1ns pulse width was obtained laser.

By adopting the steps described in this example, the (Er _0.005 Yb _0.05 Lu _0.945 ) ₂ Si ₂ O ₇ crystal can be pumped by a 976nm semiconductor laser to achieve a 1.55 μm band micro-pulse laser with a repetition rate of 100 Hz, a pulse energy of 120 μJ and a pulse width of 2.1 ns .

Example 2

The pump pulse period of the 976nm semiconductor laser in Example 1 was adjusted to 5 ms, the pump pulse width was adjusted to 1 ms, and the waist spot diameter of the pump laser in the gain medium was adjusted to 300 μm. Using the semiconductor laser end-pumped (Er _0.005 Yb _0.05 Lu _0.945 ) ₂ Si ₂ O ₇ crystal, under the pumping of 25W peak incident power, a 1.55μm band micro-pulse with 200Hz repetition frequency, 100μJ pulse energy and 2.3ns pulse width was obtained laser.

By adopting the steps described in this example, the (Er _0.005 Yb _0.05 Lu _0.945 ) ₂ Si ₂ O ₇ crystal can be pumped by a 976nm semiconductor laser to achieve a 1.55 μm band micro-pulse laser with a repetition rate of 200 Hz, a pulse energy of 100 μJ and a pulse width of 2.3 ns .

Example 3

The pump pulse period of the 976nm semiconductor laser in Example 1 was adjusted to 20 ms, the pump pulse width was adjusted to 4.0 ms, and the waist spot diameter of the pump laser in the gain medium was adjusted to 200 μm. Using the semiconductor laser end-pumped (Er _0.005 Yb _0.05 Lu _0.945 ) ₂ Si ₂ O ₇ crystal, under 15W peak incident power pumping, a 1.55μm band micro pulse with 50Hz repetition rate, 160μJ pulse energy and 1.9ns pulse width was obtained laser.

By adopting the steps described in this example, the (Er _0.005 Yb _0.05 Lu _0.945 ) ₂ Si ₂ O ₇ crystal can be pumped by a 976nm semiconductor laser to realize a 1.55 μm band micro-pulse laser with a repetition rate of 50 Hz, a pulse energy of 160 μJ and a pulse width of 1.9 ns .

Example 4-6

The (Er _0.005 Yb _0.05 Lu _0.945 ) ₂ Si ₂ O ₇ crystal in Example 1-3 was replaced by (Er _0.006 Yb _0.06 Lu _0.934 ) ₂ Si ₂ O ₇ crystal, and other settings were the same as in Example 1-3. Experimental The results were similar to Examples 1-3, respectively.

Example 7-9

The (Er _0.005 Yb _0.05 Lu _0.945 ) ₂ Si ₂ O ₇ crystal in Example 1-3 was replaced by (Er _0.006 Yb _0.07 Lu _0.924 ) ₂ Si ₂ O ₇ crystal, and other settings were the same as in Example 1-3. Experimental The results were similar to Examples 1-3, respectively.

Comparative example 10-12

Replace the (Er _0.005 Yb _0.05 Lu _0.945 ) ₂ Si ₂ O ₇ crystal in Example 1-3 with (Er _0.002 Yb _0.02 Lu _0.978 ) ₂ Si ₂ O ₇ crystal, and the other settings are the same as in Example 1-3. Realize the effect of embodiment 1-3.

Comparative example 13-15

Replace the (Er _0.005 Yb _0.05 Lu _0.945 ) ₂ Si ₂ O ₇ crystal in Example 1-3 with (Er _0.025 Yb _0.25 Lu _0.725 ) ₂ Si ₂ O ₇ crystal, and the other settings are the same as in Example 1-3. Realize the effect of embodiment 1-3.

The above are only a few embodiments of the application, and do not limit the application in any form. Although the application is disclosed as above with preferred embodiments, it is not intended to limit the application. Any skilled person familiar with this field, Without departing from the scope of the technical solution of the present application, any changes or modifications made using the technical content disclosed above are equivalent to equivalent implementation cases, and all belong to the scope of the technical solution.

Claims (6)

1. A 1.55 μm pulsed laser, characterized in that, the 1.55 μm pulsed laser includes a pump source, an input mirror dielectric film, a gain medium, a Q-switching element, and an output mirror dielectric film along the coaxial axis; The transmittance of the input mirror dielectric film in the 976nm and/or 905nm band is set to ≥90%, and the transmittance in the 1.55μm band is set to ≤0.5%; The initial transmittance of the Q-switching element in the 1.55 μm band is set to 70-95%; The transmittance of the output mirror dielectric film in the 1.55 μm band is set to 10-40%; The working mode of the pump source is a pulse working mode, the pulse period of the pulse working mode is 2-100ms, and the pulse width is 0.2-10ms; The pump source can generate laser light in the 976nm and/or 905nm band; The laser realizes 1.55 μm band single pulse laser operation within a pump pulse width by controlling the incident pump power, and the repetition frequency of the 1.55 μm band pulse laser is modulated by the pump source so that the repetition frequency of the 1.55 μm band pulse laser is the same as The pulse repetition frequency of the pump source is the same; The gain medium comprises erbium-ytterbium co-doped lutetium pyrosilicate crystal; The chemical formula of the erbium-ytterbium co-doped lutetium pyrosilicate crystal is (Er _x Yb _y Lu _(1-xy) ) ₂ Si ₂ O ₇ , where x=0.3-2.0 at.%, y=3-20 at.%. 2 . The 1.55 μm pulsed laser according to claim 1 , wherein the Q-switching element comprises a Co ²⁺ :MgAl ₂ O ₄ crystal. 3. The 1.55 μm pulsed laser according to claim 1, wherein the input mirror dielectric film is coated on the input end face of the gain medium; The output mirror dielectric film is coated on the output end face of the Q-switching element; The output end face of the gain medium and the input end face of the Q-switching element are combined by optical glue. 4. The 1.55 μm pulsed laser according to claim 1, wherein a focusing coupling mirror is arranged between the pump source and the dielectric film of the input mirror. 5. The 1.55 μm pulsed laser according to claim 1, characterized in that, there is also a sapphire crystal between the input mirror dielectric film and the gain medium, the input mirror dielectric film is plated on the input end face of the sapphire crystal, and the sapphire crystal The output end face and the gain medium input end face are combined by optical glue. 6. A light source for a laser range finder, which is the 1.55 μm pulsed laser according to any one of claims 1-5.