Abstract: A method and system for control of light transmitted through a p-type semiconductor material, configured as part of a metal-insulator-semiconductor (MIS) structure. A variable gate voltage is applied to generate a variable number of sub-band charge carriers near an insulator-semiconductor interface in the MIS structure. Where the gate voltage is lower than a threshold voltage, transmission of light propagating adjacent to and parallel to the interface is relatively high. As the gate voltage is increased to a value larger than the threshold voltage, the number of sub-band carriers raised to a first sub-band energy level increases approximately monotonically.

Abstract: Method and system for constructing and testing integrity of a combination of first and second spaced apart optical fiber couplers that each receive and hold two fibers. A segment of each fiber in a separation region between the couplers is heated, twisted and elongated by selected amounts to form a fiber complex, located between the first and second couplers. The fibers in the second coupler are subjected to further controlled elongation. A spectrum analyzer receives a common light beam passed through each of the two fibers and fiber couplers and measures successive maximum and minimum values of an interferometric variable IF and pit-to-pit or peak-to-peak spacing of the IF values as fiber segment elongation is varied.

Abstract: System and method for wavelength discrimination using a DWDM (N+1)-stage cascade tree structure with distributed filtering to provide acceptable optical isolation and acceptable flat-top wavelength response. Each channel has a Mach-Zehnder interferometer (MZI) that provides wavelength discrimination. The input channel includes an inverted Fabry-Perot etalon (FPE) filter or an inverted, non-symmetric MZI filter that helps provide a desired flat-top response. Each channel in a second stage has a selected conventional MZI filter, and each channel in a third stage has a selected FPE filter, to help provide the desired optical isolation. The number of output channels may be 32, 64 or more.

Abstract: System and method for wavelength discrimination using a DWDM (N+1)-stage fiber optic cascade tree structure with additional filtering to provide acceptable flat-top passband response, and to provide acceptable optical isolation when combined with a multilayer thin film filter. Each channel in a DWDM cascade tree structure has a conventional Mach-Zehnder interferometer (MZI) that provides wavelength discrimination. Each channel in at least one stage has an additional filter that is either (1) an inverted Fabry-Perot etalon (FPE) or (2) an inverted, non-symmetric MZI. The number of output channels may be 32, 64, 128 or more.

Abstract: Method for producing a stable, multi-port fiber optic coupler that is useful for wavelength division multiplexing (WDM). The system response is substantially independent of signal polarization and is reasonably stable against mechanical stresses and elevated temperatures. Contiguous sections of two or more fiber optic lines are alternatingly heated and elongated and are twisted according to selected process parameters for selected time intervals. The fabrication procedure uses a combination of fiber heating at two or more distinct temperatures, fiber elongation and fiber twisting, applied to two or more contiguous fiber optic lines, to produce a fused fiber optic coupler with controllable wavelength discrimination and controllable signal power coupling into each output branch of the fiber optic coupler. ITU standards for wavelength discrimination and wavelength centering in a fiber optic coupler can be met by adjustment of the process parameters.

Abstract: System and method for wavelength discrimination using a DWDM cascade tree structure with distributed filtering to provide acceptable optical isolation and acceptable flat-top wavelength response. Each channel has a Mach-Zehnder interferometer (MZI), or an MZI combined with a phase shift mechanism (a PSMZI), that provides wavelength discrimination in each channel of the structure. The phase shift mechanism may be a Gires-Tournois resonator, selectively tuned for each channel. The number of output channels may be 32, 64, 128 or more, and the light in each output channel satisfies the BellCore standards for optical isolation, flat-top wavelength response and crosstalk suppression.