Nonlinear optical phase correlator for determination of the phase of subpicosecond laser pulses in the mid-IR wavelength range

A method is proposed to determine the phase shift of the central frequency of the subpicosecond laser pulse in the mid-IR wavelength range. The method is based on the sum-frequency generation of radiation by two identical linearly polarized laser subpicosecond pumping pulses with the phase difference, propagating in GaSe crystals with a regular domain structure. It is shown that in the field of the subpicosecond IR laser pulse at the central wavelength of 9.6 A mu m propagating in the GaSe crystal with the regular domain structure with the 216 A mu m period, the simultaneous quasi-synchronous generation originates of the second, third and fourth harmonics of pumping pulses at the wavelengths 4.8 A mu m, 3.2 A mu m and 2.4 A mu m, respectively. The obtained results can be used to develop the nonlinear optical phase correlator for determination of the phase of subpicosecond laser pulse in the mid-IR wavelength range.