Lucent Technologies Inc.

US Government As Represented by the Secretary of the Army

At&t Bell Laboratories

Venkataraman Swaminathan

Sudhir B Trivedi

Sheryl Leigh Woodward

David Alan Ackerman

Robert Louis Hartman

Richard Bendicks Bylsma

John M Geary

Attilio J Rainal

Philip J Anthony

Yong-Kwan Park

Naresh Chand

Daniel Paul Wilt

George E Bodeep

Thomas H Daugherty

Leonard J Ketelsen

Deepak Bupathi

Chen-Chia Wang

Paul D Willson

Feng Jin

ChenChia Wang

Wouterus Muys

A laser vibrometer for measuring the vibratory characteristics of an object and more specifically, a moving object, has an improved signal to noise ratio due to multiple channels. A laser is split into a plurality of channels and then for each channel split again into a reference beam and a probe beam. The probe beam is directed at the object and the back scattered reflections are collected and compared to the reference beam to determine the vibratory characteristics of the object. The received signals from the multiple channels are different, sequential and non-overlapping.

Apparatus and method for improving detection precision in laser vibrometric studies

An enhanced sensitivity laser vibrometer with increased output signal strength and more sensitive surface vibration detection, is provided by using a reflective mirror assembly to repeatedly bounce the sensing laser beam against the acoustic pressure-sensing diaphragm to magnify the acoustic incident pressure wave being detected. The enhancement in signal strength, in terms of power spectral density, is a function of the number of bounces squared and the detection of surface vibrations with a displacement of smaller than 4 picometers is demonstrated experimentally.

Enhanced sensitivity vibrometer

A system for detection of optical type devices being used by an enemy sniper subject without alerting the enemy is shown. A coherent laser beam of a wave length in the visible color range, is sent along an axis and passing through a beam splitter device. A detection means is arranged to generate a signal when it detects retro-reflections from the target optical devices or subject including clutter reflections in a 180 degree direction relative to axis. The detection means is coaxially mounted with the source of illumination with a second detection means off axis therefrom to generate a second detection signal when it detects clutter reflections from the target optical devices or subject. A comparator means forms a difference signal between the retro-reflected detection signal and the second detection signal and indicates when the difference signal exceeds a predetermined threshold.

Dual color retro-reflection sensing device

This invention is a new communication system in which multichannel broadcast digital services are distributed to each user with the broadcast services signal riding in the passband above a digital baseband signal. The system can deliver more than 1 Gbps additional bandwidth to each subscriber. The passband bandwidth will accommodate growth in downstream services including video on demand, higher speed web downloads including improved streaming audio and video, HDTV, interactive video, and personalized video. The invention requires only a single fiber path and a single optical receiver for each user or group of users. A single fiber, single optical receiver system is much less expensive than two systems, one transmitting baseband and the other passband. A single receiver is greatly cost beneficial to achieving economical fiber to the home.

Optical communication system optically combining both baseband and passband signals

The invention is a laser with improved turn-on time for digital applications. The low bias capacitance effect of the laser is reduced by use of a buffer region formed between the substrate and the active region, the buffer region having a lower dopant concentration than the substrate.

Uncooled lasers with reduced low bias capacitance effect

A system and method for predicting the ratio of the strength of the carrier signal to the strength of nonlinear distortion (C/NLD) generated by a communications laser is disclosed. The method jointly evaluates the individual distortion components arising from laser clipping and from inherent laser P-I nonlinearity. According to the method, the laser P-I curve is measured with high precision to quantify the P-I nonlinearity. Various derivatives of the P-I curve are determined and then utilized to calculate C/NLD as a function of a communications network parameter such as the optical modulation index per channel or rms modulation index. Based on this information, the laser can be identified in terms of its sensitivity to RF drive variations in the field. Lasers can be tagged, etc., depending on their C/NLD sensitivity. In this manner, a laser having a C/NLD ratio appropriate for the requirements of a broadband transmission network, such as a SCM CATV system, can be selected and installed in such a system.

System and methods for assessing the suitability of analog lasers for

A temperature controlled mounting package for a fiber optic communication laser, mounted within an adapter, which is in thermal contact with a heat exchange element. The heat exchange element may be a thermoelectric cooling element or a resistance heater which maintains the laser within a temperature band. By keeping the temperature bandwidth to 40 degrees Centigrade, the signal variations are held to within 1 dB in fiber-optic applications.

Laser communication system with temperature controlled

A semiconductor distributed feedback laser having a grating with .lambda./4 phase shift which is produced by moving the left and right sections of the grating with respect to each other in a direction perpendicular to the longitudinal axis of the active region.

Phase shifted distributed feedback laser

Growing community of inventors

Bridgewater, NJ, United States of America

Venkataraman Swaminathan