Intracavity KTiOAsO₄Continuous-wave Optical Parameter Oscillater

OPO is a very important laser nonlinear frequency conversiontechnology. It can obtain the wavelength which others can not get, whichmade up the shortcomings of other lasers in this aspect. And it has thecharacter of widely tunable wavelength. Especially for the intra-cavityOPO also has the character of compact structure, low laser threshold andmany other advantages. Based on non-critical phase matching KTA–OPOhas attracted widely attention for achieving1.5μm waveband eye-safelaser and3.5μm waveband mid-infrared laser. At the present, the study inacousto-optic Q-switch operation of KTA-OPO has been very mature, butits continuous-wave OPO are seldom reported. In this thesis, theintra-cavity continuous-wave KTA-OPO was studied. Based on designingof resonant cavity and controlling of the cavity loss, the continuous-wavelaser output1.5μm and3.5μm wavebands simultaneously was achieved.Contents of this paper are summarized as follows:1. The continuous-wave KTA-OPO intra-cavity pumped by LD endpump Nd:YLF laser at1047nm was done. Non-critical phase matching(θ=90，=0)cut KTA was used as the nonlinear optical crystal. In orderto improve the power intensity of the signal light in the OPO cavity andreduce the threshold, singly resonant oscillator with high reflectivity atsignal light was designed. Under the incident pump power of8.35W, theoutput power of335mW at3440nm and110mW at1505nm wereobtained. The total conversion efficiency with respect to the incidentdiode pump power is about5.6%. It was found that the OPO conversionefficiency was limited by multi-wavelength oscillating of fundamentalwavelength in the cavity.2. The continuous-wave KTA-OPO intra-cavity pumped by LD endpump Nd:Lu0.5Y0.5VO4laser at1065nm was also done. Under theincident pump power of13.2W, the output power of630mW at3440nm and190mW at1536nm were obtained. The total conversion efficiencywith respect to the incident diode pump power is about6.2%.Theperformance of this work demonstrates that continuous-wave KTA-OPOderived by LD pumped solid laser also can produce efficient eye-safelaser and mid-infrared laser.