International Business Machines Corporation

Bardia Pezeshki

Jeffrey Alan Kash

Franklin F Tong

Stephen McConnell Gates

Robert L Sandstrom

Anthony Cyril Lowe

Jeffrey John Welser

Farid Agahi

David W Kisker

John G Crockett

By moving a substrate relative to a shadow mask in a reactive ion etching system, we are able to precisely tailor the thickness of critical layers. To minimize disturbing the plasma, all the mechanical components are kept below the anode. The system is highly reproducible, and can be programmed to yield arbitrary vertical profiles along one horizontal axis. Using silicon-on-insulator substrates, the resonance wavelength was modified as a function of position with better than 1 nm control in the vertical dimension. This technique should prove useful for optical devices where the thickness of the layers controls the device characteristics.

Thickness control of semiconductor device layers in reactive ion etch

A variable index distributed mirror is disclosed used for high resolution reflective displays that are thin and have high resolution, reflectivity and contrast; wide viewing angle; low power consumption; and low voltage operation. The mirror is electrically switchable or variable between substantially transparent and reflective states. The mirror has alternating layers of a first material having a fixed refractive index, and a second material having a variable refractive index. The second material may be a nematic liquid crystal. The alternating layers are located between a pair of electrodes. The variable refractive index approximately equals the fixed refractive index in the transparent state and differs from the fixed refractive index in the reflective state. The variable refractive index varies in response to a signal applied across the electrodes. The mirror is tuned to a particular color to form a monochrome display. Three such mirrors, each individually driven and tuned to different colors, form a color display. For a black and white monochrome display, the three mirrors are driven collectively.

Variable index distributed mirror

This invention describes how commercial silicon-on-insulator material can be used to fabricate both wavelength filters and wavelength-selective photodetectors. The silicon-on-insulator substrates have a buried silicon dioxide layer and a thin top silicon layer and are manufactured for high speed electonics applications. However, in this invention, the thin silicon layer is used as the core of a waveguide and the buried silicon dioxide as a lower cladding region. Another cladding layer and a low index waveguide is fabricated on the commercial substrate to form an asymmetric waveguide coupler structure. The added low index waveguide and the original thin silicon layer form the two waveguides of the coupler. Since the the two waveguide materials have very different indices of refraction, they are only phase-matched at one wavelength. Thus for a given thickness of materials, only one wavelength couples between the two waveguides. By adding an absorptive layer in the silicon waveguide and electrical contacts, wavelength sensitive photodetection is obtained. The buried insulator layer is the key to device operation, providing a very low index buried cladding region.

Wavelength-selective devices using silicon-on-insulator

An apparatus is described for obtaining single frequency laser operation in a coupled waveguide configuration without using a diffraction grating. More specifically, this invention is a laser structure for oscillating light in single longitudinal mode. This structure has a pair of coupled but dissimilar waveguides that are collinear with each other and separated by a mirror in contact with each of the guides. The length of the waveguides are adjusted so that frequency selective coupling between the waveguides can discriminate between wavelengths corresponding to different longitudinal modes.

Asymmetric dual waveguide laser

This invention covers an apparatus for generating multiple wavelengths of light, where the intensity of each wavelength is separately controlled, and where all the wavelengths exit the device from the same aperture. Structurally, this multiple wavelength source consists of a passive waveguide coupled to an active tapered resonator. The light generated in the resonator couples to the passive waveguide and exits from the ends of the device. By pumping different regions of the resonator, different wavelengths can be obtained.

Tapered Fabry-Perot multi-wavelength optical source

This invention covers apparatus for providing a compact, high resolution waveguide optical demultiplexer or spectrometer for application in optical communications. With this invention, incoming light composing many discrete wavelengths or optical channels is spectrally resolved by the waveguide demultiplexer such that the wavelength channels are separated spatially. The two major elements of this invention are a waveguide having a partial mirror along its length to reflect optical frequencies therein, and an optical resonator where one of its resonating mirrors is the partial mirror of the waveguide. Selected frequencies are then extracted from the waveguide and resonated in the resonator.

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Bridgeport, CT, United States of America

Bardia Pezeshki