The ability to accurately rotate the polarization of incident light while minimizing any losses in polarization purity has applications in optical switching, polarimetry, and microscopy. Polarization rotators utilizing tunable birefringent plates, such as liquid crystal (LC) devices, have the advantage of non-mechanically tuning the devices' retardance. However, these devices properly work with incident light within a very specific wavelength range. Ferroelectric liquid crystal (FLC) devices can switch between two orthogonal states of linear polarization, and offer response times much faster than their nematic liquid crystal cell counterparts. An achromatic polarization rotator can be constructed with an FLC cell between two half-wave plates that have been constructed to produce a half-wave retardance at a certain design wavelength. This results in a device that offers fast response times and high polarization purity over a broader wavelength range.
An emergent electro-optic technology platform, liquid crystal (LC) waveguides, will be presented with a focus on
performance attributes that may be relevant to coded aperture approaches. As a low cost and low SWaP alternative to
more traditional approaches (e.g. galvos, MEMs, traditional EO techniques, etc.), LC-Waveguides provide a new
technique for switching, phase shifting, steering, focusing, and generally controlling light. LC-waveguides provide
tremendous continuous voltage control over optical phase delays (> 2mm demonstrated), with very low loss (< 0.5
dB/cm) and rapid response time. The electro-evanescent architecture exploits the tremendous electro-optic response of
liquid crystals (can be > one million pm/Volts) while circumventing their historic limitations; speeds can be in the
microseconds and LC scattering losses can be reduced by orders of magnitude from conventional LC optics. This
enables a new class of photonic devices: very wide analog non-mechanical beamsteerers (270° demonstrated), chip-scale
widely tunable lasers (50 nm demonstrated), chip-scale Fourier transform spectrometers (< 5 nm resolution
demonstrated), widely tunable micro-ring resonators, tunable lenses (fl tuning from 5 mm to infinity demonstrated),
ultra-low power (< 5 microWatts) optical switches, true optical time delay devices (12 nsecs demonstrated) for phased
array antennas, and many more. Both the limitations and the opportunity provided by this technology for use in coded
aperture schemes will be discussed.
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