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CN-121983840-A - Pulse width continuously adjustable dual-gain series connection dual-cavity solid laser and working method thereof

CN121983840ACN 121983840 ACN121983840 ACN 121983840ACN-121983840-A

Abstract

The invention discloses a double-gain series-connection double-cavity solid laser with continuously adjustable pulse width and a working method thereof, and relates to the technical field of lasers. The laser comprises a main resonant cavity and a sub-resonant cavity, wherein the main resonant cavity is sequentially provided with a total reflection mirror, a first gain medium, a Q-switch and a main output mirror along a light path, the sub-resonant cavity is arranged on an output light path of the main resonant cavity, a second gain medium, a sub-output mirror and a displacement driving device are sequentially arranged along the light path, and the sub-output mirror is arranged on the displacement driving device. After the output pulse of the main resonant cavity is coupled into the sub resonant cavity, a plurality of delay pulse components are formed through a plurality of round trip reflections, and the widened pulse is output after the superposition of time domains. The optical cavity length of the sub resonant cavity is adjusted through the displacement driving device, so that the output pulse width is continuously adjustable.

Inventors

  • Zeng Rang
  • Shu Qingbang
  • Zha Gensheng
  • XING XUEBING
  • XU FAN
  • ZHU FANGSHUN

Assignees

  • 安徽华创鸿度光电科技有限公司

Dates

Publication Date
20260505
Application Date
20260407

Claims (9)

  1. 1. A dual gain tandem dual cavity solid state laser with continuously adjustable pulse width, the laser comprising: The main resonant cavity (1), the main resonant cavity (1) is sequentially provided with a total reflection mirror (101), a first gain medium (102), a Q-switch (103) and a main output mirror (104) along an optical path; The device comprises a main resonant cavity (1), a sub resonant cavity (2), a second gain medium (202), a secondary output mirror (201) and a displacement driving device (203), wherein the sub resonant cavity (2) is arranged on an output light path of the main resonant cavity (1), and the second gain medium (202), the secondary output mirror (201) and the displacement driving device (203) are sequentially arranged along the light path; The gain of the main resonant cavity (1) is larger than that of the sub resonant cavity (2), and the net gain of the sub resonant cavity (2) is lower than the self-oscillation threshold.
  2. 2. A dual gain tandem dual cavity solid state laser with continuously adjustable pulse width according to claim 1, characterized in that the ratio of the stimulated emission section of the first gain medium (102) to the stimulated emission section of the second gain medium (202) is greater than 2.
  3. 3.A dual gain tandem dual cavity solid state laser with continuously adjustable pulse width according to claim 1, characterized in that the optical cavity length of the sub-cavity (2) is larger than the optical cavity length of the main cavity (1).
  4. 4. A dual gain tandem dual cavity solid state laser with continuously adjustable pulse width according to claim 3, characterized in that the ratio of the optical cavity length of the sub-cavity (2) to the optical cavity length of the main cavity (1) is not less than 1.5:1.
  5. 5. A dual gain tandem dual cavity solid state laser with continuously adjustable pulse width according to claim 1, wherein said displacement driving means (203) is any one of a piezo ceramic driver, a voice coil motor or a stepper motor driving rail.
  6. 6. A dual gain tandem dual cavity solid state laser with continuously adjustable pulse width according to claim 1, characterized in that the sub-resonator (2) is further provided with a beam quality control element (204) for filtering out higher order transverse modes for optimizing the output beam quality.
  7. 7. The dual gain tandem dual cavity solid state laser with continuously adjustable pulse width of claim 6, wherein said beam quality control element (204) is a soft edge stop.
  8. 8. The dual-gain series-connection dual-cavity solid-state laser with continuously adjustable pulse width according to claim 1, wherein the sub-resonant cavity (2) is further provided with a frequency doubling crystal (205) and a spectroscope (206) for realizing intracavity frequency doubling.
  9. 9. A method of operating a dual gain tandem dual cavity solid state laser based on continuously adjustable pulse width of any one of claims 1 to 8, the method comprising: S1, generating an initial laser pulse in the main resonant cavity (1); s2, according to the transmittance of the main output mirror (104), the initial laser pulse part is coupled into the sub-resonant cavity (2) through the main output mirror (104); S3, carrying out multiple round trip reflections between a main output mirror (104) and a secondary output mirror (201) in the sub-resonant cavity (2) by light pulses coupled into the sub-resonant cavity (2), wherein each reflection obtains a fixed time delay and gain compensation provided by the second gain medium (202); S4, pulse parts with different time delays generated by multiple round trip reflections are overlapped in the time domain, and a pulse with a widened envelope is output from the auxiliary output mirror (201); The continuous adjustment of the output pulse width is realized by adjusting the optical cavity length of the sub resonant cavity (2).

Description

Pulse width continuously adjustable dual-gain series connection dual-cavity solid laser and working method thereof Technical Field The invention relates to the technical field of lasers, in particular to a double-gain series-connection double-cavity solid laser with continuously adjustable pulse width and a working method thereof. Background The solid pulse laser has important application in the fields of industrial micromachining, medical operation, scientific research and the like. The pulse width of the output laser is a core performance parameter, and directly influences the machining effect, the size of a heat affected zone, the physical mechanism of the action process and the like. In some specific application scenarios, such as precision drilling (taper reduction) or photoacoustic imaging (signal to noise ratio improvement), a pulsed laser capable of stably outputting a wide pulse width (tens to hundreds of nanoseconds) and excellent in beam quality is required. However, the output pulse width of the traditional single-resonant-cavity Q-switched solid-state laser is mainly limited by the gain in the cavity and the switching speed of the Q-switched switch, and the adjustment range is limited. In order to obtain wider adjustable pulses, the prior art mainly adopts the following schemes: And the cavity length switching scheme is that a mechanical device is used for switching between two different resonant cavity lengths, and the pulse width is changed along with the change of the cavity lengths. The scheme has the defects that a mechanical moving part exists, the stability and the reliability are affected, and the laser mode instability and the power fluctuation are easily caused by the abrupt change of the cavity length. An extra-cavity optical modulation scheme uses an independent electro-optic modulator at the laser output to time-domain shape and spread the output pulses. The scheme needs high-precision external circuit control, has complex system, high cost of the electro-optical modulator and a driving source thereof, and can bring extra insertion loss to reduce the efficiency of the whole system. The double-cavity coupling scheme adopts a double-resonant cavity structure to adjust pulse width. For example, patent application CN119134018a discloses a dual-cavity Q-switched laser, in which two resonant cavities with a common laser crystal and a Q-switch but different cavity lengths are formed by a rotatable half-wave plate, and the polarization state of light is changed by rotation of the half-wave plate, so that light is switched between the resonant cavities with different cavity lengths, thereby realizing the conversion of pulse width. However, although this actively switched dual-cavity structure can vary pulse width to some extent, pulse width modulation is typically stepped, relying on a limited number of discrete cavity modes, and making continuous fine tuning difficult. The prior art can not effectively solve the problem of considering both output stability and continuous adjustability of pulse width while expanding the pulse width. Disclosure of Invention The invention aims to solve the problems of discontinuous pulse width adjustment and poor system stability of the existing double-cavity structure in the background art, and provides a double-gain series double-cavity solid laser with continuously adjustable pulse width. In a first aspect of the present invention, there is provided a dual-gain tandem dual-cavity solid-state laser with continuously adjustable pulse width, the laser comprising: the main resonant cavity is sequentially provided with a total reflection mirror, a first gain medium, a Q-switch and a main output mirror along an optical path; The sub-resonant cavity is arranged on an output optical path of the main resonant cavity, and a second gain medium, a secondary output mirror and a displacement driving device are sequentially arranged along the optical path; the displacement driving device is used for adjusting the distance between the auxiliary output mirror and the main output mirror so as to change the optical cavity length of the sub resonant cavity; The gain of the main resonant cavity is larger than that of the sub resonant cavity, and the net gain of the sub resonant cavity is lower than the self-oscillation threshold. Optionally, a ratio of the stimulated emission section of the first gain medium to the stimulated emission section of the second gain medium is greater than 2. Optionally, the optical cavity length of the sub-resonant cavity is greater than the optical cavity length of the main resonant cavity. Optionally, a ratio of the optical cavity length of the sub-resonant cavity to the optical cavity length of the main resonant cavity is not less than 1.5:1. Optionally, the displacement driving device is any one of a piezoelectric ceramic driver, a voice coil motor or a stepping motor driving guide rail. Optionally, the sub-resonant cavity is further provided w