Intensity Noise Characteristics Analysis Of All-solid-state Continuous-wave Single-frequency Nd:YVO₄ Laser

With the increasing development of laser technology,lasers play an irreplaceable role in communication,military and medical according to different characteristics.Fiber lasers are used in fiber communication,laser engraving,laser cutting and other fields;semiconductor lasers are used in laser printing,laser TV,integrated optics and other fields;gas lasers are used in laser displays,holographic,printing color separation and other fields;all-solid-state continuous-wave single-frequency lasers are used in femtosecond spectroscopy,nonlinear frequency conversion,non-classical light field preparation and other fields.The laser’s intensity noise has emerged as a vital parameter due to it can significantly affect measurement accuracy or experimental outcomes.To increase the precision of laser measurement,it is necessary to study and analyze the characteristics of laser intensity noise.We have finished the following work related the low noise all-solid-state continuous-wave single-frequency Nd:YVO₄ laser in this thesis:1.The characteristics of the continuous-wave,single-frequency,all-solid-state Nd:YVO₄ laser’s intensity noise is thoroughly investigated in theory.Only a small improvement in the intensity noise can be achieved by optimizing these parameters.Resonant relaxation oscillation,which is the primary factor affecting noise level,can be changed in a way that effectively lowers the intensity of noise.The photoelectronic negative feedback technique can effectively suppress resonant relaxation oscillation by providing linear gain and phase advance;the injection locking technology can change the resonant relaxation oscillation’s state and effectively suppress the intensity noise of the laser by using a low noise injection field.The intensity noise in the relaxation oscillation zone can be suppressed more strongly by combining the two techniques.The intensity noise of the all-solid-state continuous-wave single-frequency Nd:YVO₄ laser is reduced by about 5 d B in the audio frequency region and by about 39 d B around the peak of the resonant relaxation oscillation with the feasible parameters of ε=10%,g=15 d B,φ=60°,H=20 and the real injection laser noise.2.The all-solid-state continuous-wave single-frequency Nd:YVO₄ laser and the characteristics of the intensity noise is investigated in experiments.A all-solid-state continuous-wave single-frequency Nd:YVO₄ laser at 1064 nm is demonstrated by laser diode at 880 nm.7.75 W of laser light at 1064 nm was obtained by 32 W of the pump light source,and the laser is in a single-frequency operation state.The sliding efficiency of about55%.The stability of the output power was better than±0.8%in two hours.The noise characteristics of the laser were also investigated.The resonant relaxation oscillation peak noise is 44 d B at 416 k Hz and the intensity noise reached the shot noise limit at analysis frequency of 1.2 MHz.