Abstract:
A guided-mode resonance filter is provided which can be used as an optical filter with very narrow line width and as an efficient optical switch. Diffraction efficiencies and passband frequencies are calculated based on guided-mode resonance properties of periodic dielectric structures in a waveguide geometry. The guided-mode resonance filter preferably includes means for changing various parameters within the grating (10) so as to change passband frequencies in response thereto. Also, the present invention envisions a narrowband tuneable laser having a diffraction grating of the present invention placed within a laser cavity to provide narrowband optical wave output from the narrowband tuneable laser. In another preferred embodiment, the present diffraction grating can be supported by a semiconductor substrate, preferably adjacent to a semiconductor laser for fine-tuning the output of the semiconductor laser. In still another preferred embodiment, the present diffraction grating can be placed between thin-film layers to enhance thin-film performance characteristics.
Abstract:
The invention concerns a method of reducing the increase in temperature which is produced by sunshine entering an enclosed space by the window, the method being characterized by the fact that at least part of the surface of the inside walls of the space and/or at least part of the surface of the objects present in the space have an IR-reflective coating.
Abstract:
A highly damage resistant, multilayer, optical reflective coating (20) includes alternating layers (24, 26) of doped and undoped dielectric material. The doping levels are low enough that there are no distinct interfaces between the doped and undoped layers so that the coating has properties nearly identical to the undoped material. The coating is fabricated at high temperature with plasma-assisted chemical vapor deposition techniques to eliminate defects, reduce energy-absorption sites, and maintain proper chemical stoichiometry. A number of differently-doped layer pairs, each layer having a thickness equal to one-quarter of a predetermined wavelength in the material are combined to form a narrowband reflective coating (20) for a predetermined wavelength. Broadband reflectors (55) are made by using a number of narrowband reflectors, each covering a portion of the broadband.