Spectra Diode Laboratories, Inc.

Gary L Harnagel

Donald R Scifres

William Streifer

John G Endriz

D Philip Worland

Peter Cross

Gerald S Browder

Mitra Ahrabi

A laser array submount structure for assembly into a two-dimensional stacked array with precise separation between laser diodes of adjacent submounts. The submount includes a deformable metal layer, such as a soft solder, on one major surface of a laser array support plate. A spacer element having spaced apart ridges is disposed on the opposite major surface. A laser diode array is mounted on a front edge of the support plate. In a cold bonding step, submounts are pressed together causing ridges to penetrate the deformable metal layer to a specified depth. The displaced metal spreads into channels between the ridges, allowing pressing of multiple laser array submounts into stackes of precise total tolerance.

Ribbed submounts for two dimensional stacked laser array

A plurality of diode lasers is focussed onto a single region by arranging the diodes at equally spaced locations on a first arc. Each diode laser emits light in a slit-like pattern which is characterized by orthogonal axes. In a first group of cylindrical lenses, one associated with each diode laser, each lens has a refractive surface having an axis parallel to one of the emitting axes of the laser and refracts light to a focal region of defined dimensions. Each cylindrical lens is disposed along a second arc having a circular center common with the first arc. A second group of cylindrical lenses, one associated with each laser, is also disposed on a circular arc, concentric with the other arcs, but the second group has a refractive axis perpendicular to the first refractive axis. The second group of cylindrical lenses acts upon the second axis of the source image, focussing it to the common focal region. The first and second cylindrical lens groups may be combined into a toric surface within a single lens. The cylindrical lenses may either be individual lenses, or may be combined into a lenticular array. The lenses may be simple cylindrical refractive lenses, Fresnel lenses, or holographic lenses. A bright image of the source is formed at the common focal region. The diode lasers and cylindrical lenses may be arranged in three dimensions to produce very high optical power densities.

Diode laser arrangement forming bright image

A diode laser array assembly made from a plurality of linear diode laser array subassemblies stacked one above the other. Each subassembly is an array of individual laser beam emitters, such as a laser bar, mounted on a support plate. An electrically conductive path goes from one major surface of a support plate, through the linear laser array, to an opposite major surface of the support plate. Each subassembly is connected physically and electrically to adjacent subassemblies to form the final assembly. In one embodiment, the support plates are electrically insulating and partly coated or covered with conducting material. The plates are either rectangular with projections and directly connected, rectangular with metal plates between each other, or rectangular and connected in a staircase configuration. Alternatively, the support plates may be electrically conducting with an insulating layer and a conducting layer disposed in a sandwich configuration. The plates may also be made up of an electrically insulating support plate and an electrically conducting spacer plate.

Stacked diode laser array assembly

A heterostructure semiconductor laser emitting light in a direction vertical to the horizontal active layer has one or more internal reflectors for feedback. Angled reflectors, in the form of grooves etched at an angle exceeding the angle of total internal reflection through the layers, totally internally reflect light out of the laser. One or more of the following feedback constructions are used separately or in combination to provide low threshold current and frequency selection. Insulating windows may be put on the grooves. A periodic grating on a layer adjacent the active layer provides distributed feedback. A plurality of thin dielectric layers placed next to the active layer reflect light back into the active layer. Two parallel integral feedback facets crossing vertically through the active layer act as planar mirrors.

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San Jose, CA, United States of America

Gary L Harnagel