Other

Bell Telephone Laboratories

At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Richard G Smith

Stephen R Forrest

Adrian R Hartman

Michael G Brown

Bernard C DeLoach, Jr

Charles Arthur Brackett

David P Schinke

Ock-Ky Kim

Hans Melchior

Chun-Lim Lau

A golf swing teaching aid includes an arm cuff positionable on an upper portion of a golfer's forward arm. A hand engaging member is positionable on a hand of the forward arm and has a first side, a second side, a forward edge, a rear edge, a first lateral edge and a second lateral edge. A plurality of couplers engages and urges toward each other the first and second lateral edges. An elongated rod has a cuff end and a hand end. The cuff end is pivotally coupled to the arm cuff. The hand end is pivotally coupled to the first side of the hand engaging member. The rod is straight and maintains a distance between the arm cuff and the hand engaging member. The hand engaging member and the arm cuff are positionable on the forward arm to resist bending of the forward arm during a golf swing.

Golf swing teaching aid

In accordance with an exemplary embodiment of the present invention, an optical apparatus includes a first optical element, a second optical element, and a third optical element disposed between the first and second optical elements. Light from the first optical element is incident upon the second optical element at an angle with respect to the optic axis that is substantially independent of an offset of the first optical element in a direction orthogonal to the optic axis.

Confocal optical design for optical coupling

A coherent lightwave transmitter includes a relatively low power, single frequency laser which provides an injection locking signal to a plurality of higher power lasers located in separate, parallel optical paths. A modulator is interposed between the single frequency laser and the higher power lasers, and the outputs of the latter are added constructively to form a high power transmitter output. Feedback control of the optical path lengths to maintain constructive interference is also described.

Coherent lightwave transmitters

Apparatus for monitoring structures and structural members for overloads has an elongated frangible closed ended tube containing a dense, visible liquid. The tube includes a central reduced cross-sectional area for forming a weak portion thereof. The tube is enclosed in a transparent shield and the tube and shield resiliently attached to the structure to be monitored. The frangible tube is designed to cause the weakened area to fracture when the tube and structure are exposed to a preselected level of an acceleration force, causing the liquid to be deposited in the shield as an indication of an overload.

Overload detection apparatus

Apparatus including a semiconductor laser source and means for stabilizing the frequency of the laser. A feedback signal is provided by means such as a Fabry-Perot interferometer, which signal is coupled simultaneously to two feedback loops. One loop provides high frequency control of the drive current while the other loop provides low frequency control of the laser temperature.

Frequency stabilization of lasers

An avalanche photodetector useful at wavelengths as long as 1.7 microns with low noise is achieved. The crystal used includes successive layers of p-type indium phosphide, n-type indium phosphide, and n-type indium gallium arsenide. An appropriate total of fixed charges in the n-type indium phosphide and a graded bandgap heterointerface region are important for the improved results.

Long wavelength avalanche photodetector

Described is a temperature compensation circuit comprising a transistor, a device (to which compensated voltage is to be applied) connected to the collector, and a plurality of resistors forming a voltage divider. A node separates the resistors into two branches and is connected to the base, and a temperature sensor having a negative temperature coefficient of resistance is located in one of the branches. The branches are mutually adapted so that the ratio of the resistance of the branch containing the sensor to the sum of the resistances of both branches is a linear function of temperature. An application of this circuit to the control of the bias voltage supplied to an avalanche photodiode is specifically described.

Temperature compensation circuit

Described is a method of fabricating front-illuminated silicon photodiodes having high quantum efficiency, a short response time, (high gain and low excess noise in the case of avalanche diodes), low dark currents and good reliability. In the fabrication of an n.sup.+ -p-.pi.-p.sup.+ APD the method includes the steps of: (1) epitaxially growing a high resistivity .pi.-type silicon layer on a high conductivity p-type silicon substrate; (2) forming an n-type guard ring in the .pi.-layer; (3) forming a p-type channel stop around the guard ring; (4) forming in the .pi.-layer a p-layer by ion implantation and by driving in the implanted ions by heating in a suitable atmosphere; (5) masking the p-layer and introducing phosphorus into the backside to getter defects and/or impurities; (6) ramping the furnace temperature during steps (2) through (5) to reduce crystalline defects; (7) forming a thin n.sup.+ -layer in the p-layer; (8) forming an anti-reflection and passivation coating on the n.sup.+ -layer; and (9) forming electrical contacts to the substrate, the guard ring and the channel stop so that the latter two contacts overlap the surface portions of the corresponding metallurgical junctions. The n.sup.+ -layer is made extremely thin in order to reduce hole injection caused by light incident on that layer, and the ion implantation-drive step (4) and subsequent steps which involve heating are mutually adapted so that the resultant electric field profile in the multiplication region (p-layer) is substantially triangular. A similar process, which omits step (4), is also described for the fabrication of n.sup.+ -.pi.-p.sup.+ photodiodes.

Method of fabricating silicon photodiodes

Described is a stabilization circuit for reducing the sensitivity of a junction laser to variations in the amplitude of drive current pulses. The circuit comprises a transistor connected in common emitter configuration, a junction laser connected between the collector and emitter, a photodetector connected between a voltage node and the emitter, a nonlinear element, such as a switching diode, connected between the node and the base, means for coupling a portion of the laser radiation to the photodetector, and means for coupling an input signal (e.g., current pulses) between the base and emitter. In one embodiment the photodetector is an avalanche photodiode to provide gain and the nonlinear element is a switching diode. In another embodiment the nonlinear element is a switching transistor to provide gain and the photodetector is a PIN photodiode.

Growing community of inventors

Basking Ridge, NJ, United States of America

Richard G Smith