Massachusetts Institute of Technology

Other

James N Walpole

Zong-Long Liau

Stephen R Chinn

Christine A Wang

Emily S Kintzer

Leo J Missaggia

Dale C Flanders

Tso Yee Fan

Antonio Sanchez-Rubio

Joseph P Donnelly

James R Leger

Richard C Williamson

Dean Z Tsang

Kenneth W Nill

William C Goltsos

Ivars Melngailis

Hong K Choi

Lee J Missaggia

A semiconductor optical amplification system that uses a single-mode fiber angle-coupled to a semiconductor wave-guide medium with optical gain. This design is particularly simple and relevant to optical fiber systems, but it may be generalized to include other implementations as well, in which other spatial mode filters are employed. A chip design is employed in which lowest order mode has a size greater than about 5 micrometers (&#x3bc;m). Thus, much smaller facet angles can be employed while still avoiding self-oscillation. More specifically, according to some aspects of the invention, facet angles of less than 4 to 5 degrees are utilized.

Large modal volume semiconductor laser system with spatial mode filter

A laser and optical amplifier waveguide device with a plurality of layers that supports a single lowest-order optical mode with gain while higher order modes radiate and have a net loss. The supported lowest-order mode which has gain, has a mode cross section which is large compared to the operating optical wavelength in both the transverse and lateral directions. The contours of constant optical intensity of such lowest-order can be nearly circular, having an approximately elliptical shape with a small aspect ratio.

Stab-coupled optical waveguide laser and amplifier

A semiconductor optical amplification system that uses a single-mode fiber angle-coupled to a semiconductor wave-guide medium with optical gain. This design is particularly simple and relevant to optical fiber systems, but it may be generalized to include other implementations as well, in which other spatial mode filters are employed. A chip design is employed in which lowest order mode has a size greater than about 5 micrometers (&mgr;m). Thus, much smaller facet angles can be employed while still avoiding self-oscillation. More specifically, according to some aspects of the invention, facet angles of less than 4 to 5 degrees are utilized.

In an apparatus and method for aligning a microlens relative to an edge-emitting semiconductor laser, the components are aligned and coupled without the need for intermediate optics. An edge-emitting semiconductor laser is mounted to a support body which preferably operates as a heat sink. The support body has a side face, which is substantially parallel by the emitting face of the laser. The microlens is formed on a lens substrate. The lens substrate is mounted adjacent the emitting face of the laser and further mounted adjacent the side face of the support body such that the optical axis of the lens substantially aligns with the optical axis of the laser. A substantial portion of the lens substrate extends along the plane of the side face of the support body. The invention has applications in coupling high-power laser energy into fiber optics and in optical computing devices requiring arrays of lasers.

Compact micro-optical edge-emitting semiconductor laser assembly

A semiconductor laser oscillator structure and method is described having a tapered gain region in one-half of a laser cavity and a confocal oscillator region in another half of the cavity. An aperture is formed between two pairs of cavity spoilers located between the two cavity halves. One pair of spoilers is provided for receiving light which is reflected off of an output facet back into the semiconductor and removing it from the gain region. The other pair of spoilers removes light reflected from a curved mirror surface formed at the end of the other laser cavity half.

Tapered semiconductor laser oscillator

A semiconductor laser gain structure having a tapered gain region comprising cavity spoilers for receiving light which is reflected off of the output facet back into the semiconductor and removing it from the gain region so as to reduce or eliminate self-oscillation. The boundaries of the gain region are also designed to have a very low refractive index gradient so as to minimize reflection of light off of the boundaries back into the gain region. The gain structure may be embodied in a semiconductor laser oscillator or semiconductor laser amplifier depending on whether the input facet is or is not, respectively, anti-reflection coated. The output facet is anti-reflection coated in either embodiment.

Tapered semiconductor laser gain structure with cavity spoiling grooves

A semiconductor laser gain structure having a tapered gain region comprising cavity spoilers for receiving light which is reflected off of the output facet back into the semiconductor and removing it from the gain region so as to reduce or eliminate self oscillation. The boundaries of the gain region are also designed to have a very low refractive index gradient so as to minimize reflection of light off of the boundaries back into the gain region. The gain structure may be embodied in a semiconductor laser oscillator or semiconductor laser amplifier depending on whether the input facet is or is not, respectively, anti reflection coated. The output facet is anti-reflection coated in either embodiment.

A strained quantum-well diode laser with an AlInGaAs active layer and AlGaAs cladding and/or confining layers on a GaAs substrate is provided. AlInGaAs/AlGaAs lasers can be configured in laser geometries including ridge, waveguide, buried heterostructure, oxide-defined, proton-defined, narrow-stripe, broad-stripe, coupled-stripe and linear arrays using any epitaxial growth technique. Broad-stripe devices were fabricated in graded-index separate confinement heterostructures, grown by organometallic vapor phase epitaxy on GaAs substrates, containing a single Al.sub.y In.sub.x Ga.sub.l-x-y As quantum well with x between 0.14 and 0.12 and y between 0.05 and 0.17. With increasing Al content, emission wavelengths from 890 to 785 nm were obtained. Threshold current densities, J.sub.th 's, less than 200 A cm.sup.-2 and differential quantum efficiencies in the range 71 to 88 percent were observed.

Reliable AlInGaAs/AlGaAs strained-layer diode lasers

Apparatus and method for scaling solid-state devices to higher power using multiple sources each of which are separately collimated, followed by focusing of the pump radiation into gain medium colinear to laser mode using a moderated focus. A modularized system is also described.

Multiple-laser pump optical system

A microchannel heat sink with coolant flowing in alternate directions in adjacent channels. The microchannel heat sink is used for cooling the electronic device making thermal contact with the surface of the heat sink. The alternate directions of the coolant flow eliminate temperature variation along the channel length caused by the heating of the coolant. This new 'alternating channel flow' heat sink design achieves a nearly uniform temperature and thermal resistance on the surface of the heat sink and effectively cools the electronic device in contact.

Microchannel heat sink with alternating flow directions

A method and apparatus for forming a monolithic surface emitting laser diode array by providing vertical partly light transmissive mirror surfaces opposite parabolic light reflective mirror surfaces formed adjacent the active buried layer of a heterostructure diode laser. The mirror surfaces are preferably formed using a mass-transport heating process. Other mirror shapes may be formed in accordance with the invention.

Method of forming a surface emitting laser

A surface emitting laser is described with a monolithic integrated lens formed in one side of an optical semiconductor substrate aligned with a parabolic light reflective mirror surface formed adjacent an edge emitting laser formed on, or in, the other side of the substrate. An optional optical feedback spherical mirror is formed concentric to the lens.

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Concord, MA, United States of America

James N Walpole