A spatial light modulator design consisting of cascaded or sandwiched layers of ferroelectric liquid crystals (FLC’s) is investigated. The interrelation between the FLC material, the polarization of the incident illumination, and the achievable modulation states is characterized. Magnitude modulation is accomplished by standard methods by addressing the FLC layer with linearly polarized light and following it with a properly oriented analyzer. When the FLC is addressed with circularly polarized light, lossless phase modulation results with the phase states separated by twice the angle of rotation of the optical axes. A continuum of elliptical polarization states ties together the lossless phase states achievable by using circular polarization with the more well-known 0°–180° phase states obtainable with linearly polarized light. Layers of various bistable FLC materials can be cascaded, possibly with polarization control layers between some of the layers, to yield a spatial light modulator that produces multiple quantized bits of complex-valued modulation and with independent control of magnitude and phase states. Four-state phase modulation, ternary amplitude–phase modulation, and four-state magnitude modulation are demonstrated experimentally by using two layers of FLC.
© 1992 Optical Society of America
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