Polarization Rotator for Powerful Femtosecond Midinfrared Laser Pulses

The optical scheme is presented for rotation of laser pulses polarization based only on reflective elements. The losses and the degree of depolarization introduced by this scheme for laser radiation of the visible, near, and midinfrared ranges are determined. The possibility of using the device in the terahertz frequency range is shown. Numerical analysis was performed using experimentally measured complex reflection coefficients for radiation at wavelengths of 532, 808, and 3900 nm for gold mirrors with a protective coating. The possibility of using the rotator for continuous rotation of the polarization of femtosecond laser pulses of the midinfrared range is experimentally shown. It was found that for femtosecond laser pulses at a central wavelength of 3.9 μm (wavelength range of 3600–4200 nm), the losses introduced by the rotator are less than 8% and the degree of polarization in this case varies from 0.95 to 0.985 depending on the rotator position