Phase offset determining of the central frequency laser pulse with the duration of a few cycles with respect to envelope

Abstract

A method for the phase offset determining of the central frequency laser pulse with the duration of a few cycles with respect to envelope is proposed. The method is based on generating the difference frequency radiation by mutually orthogonal linearly polarized laser pulses propagating in the GaSe crystal with regular periodical domain structure. The dependence of the difference frequency radiation wavelength corresponding to the maximum of the spectrum on the phase difference between the mutually orthogonal linearly polarized pump pulses is obtained. The dependences of normalized spectral densities of the difference frequency radiation pulses on the phase differences between the pump pulses are obtained. This paper addresses the case, where the durations of the interacting pulses are equal to 30 fs, the central wavelengths are 1.98 μm and the difference frequency radiation wavelength is in the range of 8–12 μm. As shown, this method could be applied for phase locking of two femtosecond fiber optic lasers.