| Abstract: | In an embodiment, an optical filter device includes an input polarizer
for selectively transmitting an input signal. The device includes a
wave-plate structure positioned to receive the input signal, which
includes first and second substantially zero-order, zero-wave plates
arranged in series with and oriented at an angle relative to each other.
The first and second zero-wave plates are configured to alter a
polarization state of the input signal passing in a manner that depends
on the power of the input signal. Each zero-wave plate includes an entry
and exit wave plate each having a fast axis, with the fast axes oriented
substantially perpendicular to each other. Each entry wave plate is
oriented relative to a transmission axis of the input polarizer at a
respective angle. An output polarizer is positioned to receive a signal
output from the wave-plate structure and selectively transmits the signal
based on the polarization state. |