Sri International

Gas Research Institute

Pajo Vujkovic-Cvijin

David E Cooper

An optical light source for use in wavelength division multiplexed and dense wavelength division multiplexed systems may include a reference gas contained by a hermetically sealed enclosure which also protects a plurality of light generating structures. A frequency grid generator, typically in the form of an optical etalon, can be frequency referenced to an absolute reference point provided by the reference gas. An electronic feedback control system acts upon injection current to keep the laser frequency coincident with that of the referencing structure. An active, feedback based, thermal management systems provides control of the laser frequency ranges and etalon operating point. Electronic control over a number of separate lasers (and the grid) may be effected using a multiplexed digital controller.

Dense wavelength division multiplexing (DWDM) fiberoptic source

A high performance reconfigurable DWDM transmitter incorporates discrete optical components placed in v grooves etched in a substrate. Direct wavelength monitoring can be achieved with wavelength modulation locking applied independently to a gas absorption line and to etalon fringes. A set of equally-spaced wavelengths may be provided by a set of lasers, or a single laser can be used for a number of fixed frequencies.

Reconfigurable multichannel transmitter for dense wavelength division multiplexing (DWDM) optical communication

This specification discloses a method and apparatus for the mobile and remote detection of a gas, such as methane, in the atmosphere. The apparatus includes a TDL based Light Detection and Ranging (LIDAR) driven at carrier frequency lying within the absorption line of the gas. The apparatus also drives the TDL with a modulation frequency to generate upper and lower sidebands in the output of the TDL and with a low ramp frequency to sweep the output of the TDL across twice the width of the pressure-broadened absorption line of the gas, preferably the first overtone absorption line in the case of methane detection. Suitable power for remote detection through use of the TDL is provided by a master oscillator/fiber amplifier transmitter has no moving or adjustable parts at all. An all-solid-state monolithic and integrated amplifier is achieved, which leads to a compact and virtually maintenance-free LIDAR system. The remote detection apparatus includes reference and calibration cells or chambers, and includes a light collector and detectors to detect the quantity and modulation of the light that passes the reference or calibration cells and that is received by the apparatus after reflection back toward the apparatus from an uncooperative target. The apparatus further includes a signal processor that applies a derivative spectroscopy technique, such as frequency modulation spectroscopy or wavelength modulation spectroscopy, to determine the presence of the gas in the atmosphere.

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Mountain View, CA, United States of America

Pajo Vujkovic-Cvijin