Kent Optronics, Inc. has developed two tunable filter technologies, i.e., tunable band-pass filter and tunable notch filter, respectively, based on 1-D photonics crystal made from high figure of merit (FoM) liquid crystal materials.
KOI's optical tunable notch filters dynamically reject a narrow band spectral radiation while at the same time let the rest broadband light energy pass. We have two tunable notch filter technologies, i.e., (a) polarizer-free tunable notch filter, and (b) switchable-tunable notch filter. The polarizer-free tunable notch filters are made from a liquid crystal film with an electrically variable Bragg period. The switchable-tunable notch filter is made from active polarizers and a tunable LC phase retarder, which enables the filter to be switched between light blocking and nonblocking states with 2X higher transmittance over a super wide spectral range.
KOI's tunable band-pass filters are made from a special liquid crystal in a unique configuration. The uniqueness is that the filters permit a bandwidth that can be independently varied, while the center wavelength is tuned. Such filters are termed as variable bandwidth tunable filter (VBTuF).
Switchable-tunable notch filter
VBTuF in narrow band scan (3.2 nm)
VBTuF in broadband scan (50 nm)