Phase-only modulation of light

We disclose the method to obtain polarization insensitive phase-only modulation that preserves both the state and the degree of polarization of light modulated using a medium with controlled birefringence. We find that, in the double-pass configuration involving reflection from the Faraday rotator mirror, such a medium acts as the phase-only modulator. The experimental data measured in the Michelson-interferometer-based setup for deformed-helix ferroelectric liquid crystal cells are found to be in good. agreement with the theoretical results. For such cells, we experimentally demonstrate high-frequency (4 kHz modulation rate) 2 pi phase-only light modulation governed by the average phase shift and solve the problem of optical axes switching. (C) 2020 Optical Society of America