Optimization and Fine-Tuning of Controlled White-Light Continuum Generation in Transparent Solid Medium by 1-kHz Repetition Rate Femtosecond Laser Pulses

Abstract

We report on the generation and optimization of the well-controlled white-light continuum in 1-mm thick sapphire plate by 1-kHz repetition rate 30 fs laser pulses. The white-light continuum generation observed and investigated by using general purpose digital camera and broadband spectrometer. We controlled the incident seed beam power by neutral density filter, variable iris, and focusing lens. Further, we employed two collimating parabolic mirrors and a variable iris to control the collimation of a white-light continuum extended from 400 nm to 1100 nm. The incident seed beam energy and focal position within the optical medium are found critical to stabilizing and controlling the white-light continuum generation. We have investigated and observed the blue-shift in white-light continuum generation at lower incident seed beam power and multi-filamentation at the higher power of the incident beam. The white-light continuum triggering and initializing processes are discussed and reviewed briefly. We have also fine-tuned the white-light continuum generation spectrum by changing the grating separation in the compressor.