Massachusetts Institute of Technology

Han Q Le

Mark Alexander Hollis

Arthur R Calawa

Frank W Smith

Vicky Diadiuk

Tso Yee Fan

Antonio Sanchez-Rubio

William D Goodhue

A high-power external cavity laser source is described. The laser source includes a free space external cavity. At least two multimode optical gain elements are positioned in the cavity. Each gain element generates multimode optical radiation having one of at least a first and a second wavelength and one of at least a first and a second free space optical path, respectively. In another embodiment, at least two optical fiber gain media are positioned in at least two respective free space optical paths and each gain media generates optical radiation having one of at least a first and a second wavelength, respectively. An optical element is positioned in the cavity such that its focal plane is substantially located at the at least two optical gain elements and such that it intercepts the at least two respective free space optical paths. A dispersive element is positioned in the at least two optical paths. A partially reflecting element is also positioned in the at least two optical paths. The partially reflecting element and the gain media together form a free space laser cavity that defines the at least first and second wavelength. In operation, the partially reflecting element transmits an overlapping or coaxial beam comprising radiation having the at least first and second wavelength.

High-power multi-wavelength external cavity laser

An ultra-high-speed photoconductive device is described which comprises a homoepitaxial semi-insulating III-V layer, or body, upon which ohmic/conductive contacts, or strips, separated by a small gap, are formed. The semi-insulating body, or layer, is produced by low temperature growth of III-V compounds by MBE. In a GaAs embodiment, the layer is grown under arsenic stable growth conditions, at a substrate temperature preferably in the range of 150.degree. to about 300.degree. C.

Ultra-high-speed photoconductive devices using semi-insulating layers

This invention provides an optical converter suitable for use as the gain medium in lasers, optical amplifiers and other optical devices. The converter consists of at least one and preferable two or more optical converter elements which are sandwiched and separated by inactive dielectric layers. An optical pump beam may be passed to the active converter elements through an anti-reflection layer at one surface of the converter and a high reflection mirror may be provided at the opposite side of the converter to reflect the pump beam incident thereon back into the converter for a second pass. Each converter element has one or more absorber layers, at least one radiation layer receiving energy from the absorber layers and preferably outputting energy at a slightly different wavelength than the wavelength at which the absorber layers optimally absorb, and preferably at least one index-of-refraction compensator (IRC) layer which compensates for changes in index-of-refraction induced by the absorber and radiator layers to provide a low divergence far field optical intensity profile for the converter with no substantial side lobes.

Solid state optical converter

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Newton, MA, United States of America

Han Q Le