Nonlinear polarization interferometer for enhancement of laser pulse contrast and power.

A method for enhancing the temporal contrast of high-power femtosecond laser pulses is proposed. The suppression of low-intensity radiation and the simultaneous 100% transmission of a pulse peak are attained due to the nonlinear phase difference π between the orthogonally polarized waves, leading to a 90-degree rotation of polarization. The polarization interferometer has an in-line geometry that does not demand spatial beam separation. The output pulse compression and power enhancement are implemented as a result of self-phase modulation in the interferometer and subsequent reflection from the chirping mirrors.