Opto Power Corporation

Rushikesh M Patel

Michael M Ung

Stewart Wayne Wilson

Swaminathan Thandalai Srinivasan

Rajiv Agarwal

Sheng-Hui Yang

Lesley Rogers

Shantanu Gupta

Henri Nahapetiance

Robin R Pleak

Kenneth Joseph Thibault

Steve Marcomber

Robert Morris

The screening of edge-emitting laser diode bars in a production line is permitted by fabricating the source electrodes of each diode in the bar in two parts spaced apart to form a window aligned with the lasing cavity of the diode. Such windows have been made in failed devices to determine the cause of failure. Here, the windows are formed in a wafer stage of fabrication for later separation into laser bars or individual laser diodes. All wafers, all laser bars and all laser diodes are fabricated with windows thus permitting automatic screening during fabrication rather than opening a window to examine only failed devices as is the case in the prior art.

Diode laser with screening window and method of fabrication

A substrate comprising, for example, a copper-beryllium oxide ceramic-copper sandwich permits a laser diode along with cooperative components to be soldered in place using a high temperature solder. The sandwich structure is operative to move the effective thermal properties of the copper more towards that of the beryllium oxide thus reducing, for example, any stress which might occur between the solder, the substrate, and the laser diode. The use of high temperature solder provides for significantly improved operation.

Semiconductor laser diode multi-chip module

Semiconductor laser diodes or diode bars are assembled into stacks by a method which permits testing of an entire stack at once and which uses only high temperature solder. The stack includes a plurality of submounts which resemble elongated bars which are square in cross section. Laser diodes (or diode bars) are sandwiched between adjacent submounts. Each submount has an elongated mesa and the mesas are so shaped and positioned in the stack to form a set of ridges which fit into a set of grooves in a substrate. The diodes are bonded to adjacent submounts in a stack simultaneously by reflowing solder preforms (high temperature) in a reflow oven. The stack is secured in place in the grooves of the substrate by reflowing solder placed at the bottom of the grooves.

Semiconductor laser array stack package & method of fabrication

Multi-layer, semiconductor devices are configured to reduce stress by the removal of much of the structure which does not actually contribute to device performance. In one embodiment, trough between mesas which define light emitting facets in a laser diode bar are etched well into the substrate to remove all layers of different compositions there. In another embodiment, troughs are also etched in the backside of the substrate of a laser diode structure where the troughs are aligned along axes perpendicular to the axes of the mesas. The removal of stress permits more accurate alignment of the multiple facets along a single axis when the laser bar is bonded to a heat sink. The accurate alignment minimizes the placement constraints on the position of a microlens for achieving maximum power output and coupling efficiency for optical fibers coupled to the microlens.

Multi-layer semiconductor devices with stress-relief profiles

Square cross section optical fibers are accurately positioned for coupling light from laser diode emitting facets through a fiber lens. The fibers are placed in parallel channels formed in a photolithographic layer on a planar surface of a substrate and constrained in place by a retention plate. The fibers extend beyond the retention plate unrestrained by photoresist but overlying the exposed portion of the planar surface of the substrate. The fibers over the exposed portion are cemented in place and the photoresist layer is then removed leaving the constrained portion of the fibers in very accurately defined positions, and free of epoxy cement, for abutment to the familiar fiber lens.

Fiber-coupled laser device using square cross section fibers and method

A laser diode structure includes a metallic gasket which is sandwiched between the laser diode submount and the backside electrode in the absence of solder interfaces. The gasket has mirror image, shallow recesses in the surfaces thereof with each surface having the general shape of a wing. The recesses are formed into sealed coolant conduits when the several layers are bonded together into an integrated structure. The narrow end of each recess communicates with an aperture through the adjacent layer to provide inlet and outlet ports for the coolant. The gasket has an aperture therethrough at the wide ends of the recesses for the coolant to circulate. The gasket can be formed from a single layer or from two layers each with a single recess.

Laser diode structure with integrated heat sink

An assembly of simple, like laser diode submounts or laser diode bars lend themselves to volume manufacturing techniques. Individual diodes, or diode bars are supported on electrically-insulating submounts which have electrically-isolated metallizations applied thereto for mounting on a single insulating plate and to one another in a stack and for mounting to a common heat sink.

Laser diode array

A reduced, lateral mode laser diode is fabricated using a self-aligning process which produces a well controlled weakly index-guided waveguide with strong current confinement. The structure includes ion implants for controlling current injection into the active region from the top of the ridge. The number of modes may be reduced to unity, resulting in a single lateral mode laser. A laser diode array is fabricated in the same way.

Reduced mode laser and method of fabrication

A laser package includes a housing and a subassembly to which the critical components of the laser package are mounted. The subassembly is structured to preserve component alignment even in the presence of thermal excursions by ensuring that any movement which might occur effects all the components in a way to preserve alignment. The subassembly is easily removable from the housing and thus permits replacement if a failure should occur. A reverse diode is included to provide a path for reverse currents which otherwise would be damaging to the active laser diode.

Laser package with reversed laser diode

A laser package includes a housing and a subassembly to which the critical components of the laser package are mounted. The subassembly is structured to preserve component alignment even in the presence of thermal excursions by ensuring that any movement which might occur effects all the components in a way to preserve alignment. The subassembly is easily removable from the housing and thus permits replacement if a failure should occur. A reverse laser diode is included to provide a path for reverse currents which otherwise would be damaging to the active laser diode.

Laser package with permanently aligned critical components

A laser package is designed for large scale assembly by machinig a piec3 part of relatively large dimensions where the part has a slot for holding a laser. The piece part is mounted on heatsink of like dimensions. A second piece part includes an elongated groove for holding a fiber lens plate where the second piece part is mounted against the edge of the heat sink such that the lens is properly aligned with the laser. Thus, the critical alignment of the laser and the fiber is achieved by the alignment of like dimensioned piece parts of relatively large dimensions.

Laser package and method of assembly

Modified laser submounts are positioned in grooves in the surface of a monolithic substrate permitting not only relatively high packing diversities, but also pretesting and easy replacement of any submounts which may later become defective in the field. The assembly may be connected directly to a heat sink or may include an integral microchannel cooler.

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Tucson, AZ, United States of America

Rushikesh M Patel