A porous silicon filter for wavelength multiplexing and de-multiplexing.
Preferred embodiments include rugate-type porous silicon filters with
pores having continuously varying widths with pore depth an optical cross
connect switch. In other preferred embodiments, the pores are filled with
a material that changes index of refraction with changes in applied
voltage, current or temperature. Important applications of these porous
silicon filters are for multiplexing and de-multiplexing in fiber optic
communication systems. For example, a preferred embodiment is an all
optical fiber optic switch utilizing these filters.