Novel, polarization-insensitive, birefringent,
broadband tunable filter arrangements that allow high
throughput, based on a combination of tunable birefringent
layers or
polarization dependent filters, in combination with one or more of the following components (i) thin film achromatic quarter waveplates based on the form
birefringence of
dielectric subwavelength
grating structures, (ii) nano wire-grid polarizers made of metallic wire grids; (iii) omnidirectional
dielectric mirrors, (iv) polarization conversion mirrors, (v) reflective polarized
beam splitters for circularly polarized light, (vi) metallic subwavelength gratings with lines having
Gaussian profile, and (vii) Faraday mirror. All of these components may be implemented in thin film form on one or more substrates, such that a compact and cost effective filter can be produced. The birefringent
layers can be any birefringent or
magneto-
optic layer but especially liquid crystals. The use of novel polarization conversion disposition of the components of the filter results in a filter having high
throughput.