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 µm propagating in the GaSe crystal with the regular domain structure with the 216 µm period, the simultaneous quasi-synchronous generation originates of the second, third and fourth harmonics of pumping pulses at the wavelengths 4.8 µm, 3.2 µm and 2.4 µm, 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.