Deep ultraviolet lasers have various applications in industries and scientific researches.For 266-nm ultraviolet (UV) laser generation,the good beam quality of 1064-nm laser and the elimination of gray-tracking effect of KTP crystal are two key factors.Using a dynamically stable resonator design,1064-nm laser with an average power of 52W is realized with repetition rate of 16 kHz.The measured M2 factor characterizing the beam quality is 1.5.By the elimination of gray-tracking effect of KTP crystal,an 18-W green laser is realized with the M2 factor of 1.6.Using a BBO crystal for the fourth harmonic generation,a 1.9-W 266-nm UV laser is achieved.
Spherical aberrations of the thermal lens of the active media are severe when solid state lasers are strongly pumped.The fundamental mode profile deteriorates due to the aberrations.Self-consistent modes of a resonator with aberrations are calculated by using the Fox-Li diffraction iterative algorithm.Calculation results show that the aberration induced fundamental mode beam quality deterioration depends greatly on the resonator design.The tolerance of a flat-flat resonator to the aberration coefficient is about 30λ in the middle of stability,where λ is the wavelength of laser beam.But for a dynamically stable resonator,2λ of spherical aberration will create diffraction loss of more than 40%,if inappropriate design criteria are used.A birefringence compensated laser resonator with two Nd:YAG rods is experimentally studied.The experimental data are in quite good agreement with simulation results.
