| Due to its long detection range,accurate measurement,strong anti-interference ability and its wide application in military and civilian applications,laser ranging radar has become one of the hot topics in recent years.2?m solid-state lasers have The safety of the human eye and the strong atmospheric transmission capability,and the detection technology is relatively mature,becoming the preferred light source for the laser ranging radar transmitter.The injection frequency locking technology can provide single longitudinal mode,narrow line width,high frequency stability and high pulse energy.The single-frequency pulsed laser with narrow pulse width and high peak energy satisfies the requirements of the laser ranging radar for the transmitter.This topic focuses on the injection frequency-locking technology to obtain a single-frequency pulsed laser with a narrower pulse width for 2?m Ho:YAG injection of frequency-locked solid-state lasers,the subject carried out related research work.Theoretically,based on the classical theory of interaction between light and matter,the physical mechanism of seed light-induced output single-frequency pulse and the lateral mode matching and longitudinal mode matching that need to be satisfied in the seed light injection coupling process are studied.For longitudinal mode matching,the influence of seed optical frequency detuning on injection power is studied.The coupling efficiency problem is studied for transverse mode matching.The factors affecting laser energy extraction efficiency and pulse width are analyzed.In the laser design process,the thermal focal length effect of the crystal was studied.The ABCD matrix was used to study the spot change in the laser cavity and the stability of the cavity.In terms of experiments,the injected frequency-locked laser usually consists of three parts,the main laser,the slave laser and the injection coupling part.For the main laser,a non-planar annular cavity is used to obtain a single-frequency continuous light with higher power and high frequency stability.The different characteristics of the output light were studied.Then,two kinds of slave lasers with short cavity length were designed and analyzed.The characteristics of the continuous output light were studied.The pulsed light output was obtained by the acousto-optic Q-switching technique,and the different repetition frequencies were explored.The pulse output characteristics are designed,and the injection coupling system is designed.The requirements for the successful injection coupling are analyzed.The transverse mode matching is realized by beam transformation,and the longitudinal mode matching is completed by ramp-hold-fire technology.On the basis of the above work,the injection frequency locking operation of two kinds of resonant cavities is completed.The two different slave laser rectangular cavities with and without convex lens compensation are respectively analyzed,and the frequency-locking phenomenon is analyzed.The injection frequency is successfully realized for the rectangular cavity without convex lens compensation.The single-frequency pulse laser output with 200 Hz,single pulse energy 2.23 mJ and pulse width 50 ns is obtained.The pulse setup time,energy and pulse width before and after injection are analyzed.However,for the rectangular cavity compensated by the convex lens,the injection frequency is not realized due to the instability of the resonance signal.The cause of the signal instability is analyzed and studied,which has certain guiding significance for the future injection frequency locking operation. |
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