Femtosecond laser-induced phase modulation based on KTP crystal

The femtosecond laser-induced phase modulation based on KTP crystal is demonstrated. The phase modulation in femtosecond laser irradiated area is deduced through Drude model and color centers model, and the phase shift was also measured by cyclic radial shearing interferometer. As a result, a phase modulator with 2π phase shift is achieved using a 2.5-mm-thick KTP crystal and femtosecond laser pulses, and the spatial distribution of phase shift was also given. Such approach will be of great potential values for optical cross-connect switching, laser beam steering, low-cost electro-optic sensor, adaptive optics, coherent beam combination.