Enhancing the time contrast and power of femtosecond laser pulses by an optical wedge with cubic nonlinearity

A method is proposed for enhancing the time-domain contrast of femtosecond laser pulses under nonlinear pulse compression by means of spectrum broadening due to the self-phase modulation with a following reflection from chirped mirrors. The contrast increases because the radiation of the pedestal is blocked by a square screen arranged in a focal plane of a unit-magnification telescope, and the main pulse ‘bypasses’ the screen, because a wedge in front of the telescope declines the pulse to a large angle due to a cubic nonlinearity.