Photonic crystal reflectors/filters and displacement sensing applications

An optical apparatus comprising:

• at least one photonic crystal and a reflective medium adjacent to one another, said at least one crystal comprising a block of dielectric material with one or two dimensionally periodic index contrast introduced into the dielectric material;
• and
• a device controlling a distance between the at least one crystal and the reflective medium to adjust the wavelengths of radiation transmitted or reflected by the crystal.

A method controlling optical characteristics of an optical device, comprising:

• placing at least one photonic crystal and a reflective medium adjacent to one another, said at least one crystal comprising a block of dielectric material with one or two dimensionally periodic index contrast introduced into the dielectric material, said
• controlling a distance between, or a lateral shift or relative rotation between, the crystal and the reflective medium to adjust the wavelengths of radiation transmitted or reflected by the at least one crystal.

An optical apparatus comprising:

• two structures adjacent to one another, at least one of said structures comprising a dielectric material with one or two dimensional index contrast introduced into the dielectric material;
• and
• a device controlling a distance between the structures to adjust the wavelength of radiation transmitted or reflected by the structures.

An apparatus comprising at least two photonic crystals adjacent to one another, each of said crystals comprising a block of dielectric material with one or two dimensionally periodic index contrast introduced into the dielectric material, wherein the at least two photonic crystals are placed so that they form an optical cavity.