Thermal lensing measurements of Ti: sapphire crystal by an optical wavefront sensor

The effects of thermal lensing appear to be dominant in lasing crystals as the power of optical pump pulses increases. This instigates the confined heating effects in crystals. The nonuniform distributions of temperature lead to the variability of spatial refractive index in the lasing crystals and consequently, the thermal effects become prominent. The thermal effects of Brewster‐cut Ti: sapphire crystal are measured in this study. The Ti: sapphire crystal is seeded at a wavelength of 800 nm of energy ∼7 nJ and pulse duration of ∼8 fs and pumped by the 25‐ps pulses at 532 nm operating at 80 MHz. The effects of thermal lensing at ∼40 and 293 K are measured as a function of average pump power which is controlled by the automatic attenuator. The measurements of wavefronts and aberration effects are carried out by using the Shack‐Hartmann optical wavefront sensor (HASO4). This study could pave a way to suppress the thermal lensing effects at a high repetition rate laser system and to correct the wavefront aberration for ultrahigh‐intensity and metrology experiments.