International Business Machines Corporation

Bookham Technology Limited

Uniphase Laser Enterprise Ag

Christoph S Harder

Heinz P Meier

Abbas Behfar-Rad

Heinz Jaeckel

Albertus Oosenbrug

Peter D Hoh

Susanne Pawlik

Berthold Schmidt

Hans P Wolf

Wilhelm Heuberger

Achim Thies

Peter Vettiger

Peter Roentgen

Rolf Clauberg

Kurt R Grebe

Wolfgang D Pohl

Peter L Buchmann

Gary W Rubloff

David J Webb

William P Risk, Iii

Greg Costrini

Wilfried Lenth

Pierre L Gueret

Alfred Phillips, Jr

Marcel Gasser

Abram Jakubowicz

Mark E Jost

Werner Baechtold

Erich P Stoll

Ernst E Latta

Ronald F Broom

Eberhard Latta

Arsam Antreasyan

Heinz Richard

Alexis Baratoff

Stefan Hausser

Myra N Boenke

Urs Deutsch

Sridhar V Iyer

Theodor Forster

Andreas Daetwyler

Christan Heusch

Erica Williams

William Patrick

Otto Vogeli

Semiconductor laser diodes, particularly high power AlGaAs-based ridge-waveguide laser diodes, are often used in opto-electronics as so-called pump laser diodes for fiber amplifiers in optical communication lines. To provide the desired high power output and stability of such a laser diode and avoid degradation during use, the present invention concerns an improved design of such a device, the improvement in particular significantly minimizing or avoiding (front) end section degradation of such a laser diode and significantly increasing long-term stability compared to prior art designs. This is achieved by establishing one or two 'unpumped end sections' of the laser diode. One preferred way of providing such an unpumped end section at one of the laser facets () is to insert an isolation layer () of predetermined position, size, and shape between the laser diode's semiconductor material and the usually existing metallization (). A further embodiment shows separate, further isolation layers () extending along the laser diode, potentially abutting the ridge waveguide of the laser.

High power semiconductor laser diode

Semiconductor laser diodes, particularly high power AlGaAs-based ridge-waveguide laser diodes, are often used in opto-electronics as so-called pump laser diodes for fiber amplifiers in optical communication lines. To provide the desired high power output and stability of such a laser diode and avoid degradation during use, the present invention concerns an improved design of such a device, the improvement in particular significantly minimizing or avoiding (front) end section degradation of such a laser diode and significantly increasing long-term stability compared to prior art designs. This is achieved by establishing one or two &ldquo;unpumped end sections&rdquo; of the laser diode. One preferred way of providing such an unpumped end section at one of the laser facets ( ) is to insert an isolation layer ( ) of predetermined position, size, and shape between the laser diode's semiconductor material and the usually existing metallization ( ).

As will be described in more detail hereinafter, there is disclosed herein a titanium nitride diffusion barrier layer and associated method for use in non-silicon semiconductor technologies. In one aspect of the invention, a semiconductor device includes a non-silicon active surface. The improvement comprises an ohmic contact serving to form an external electrical connection to the non-silicon active surface in which the ohmic contact includes at least one layer consisting essentially of titanium nitride. In another aspect of the invention, a semiconductor ridge waveguide laser is disclosed which includes a semiconductor substrate and an active layer disposed on the substrate. A cladding layer is supported partially on the substrate and partially on the active layer. The cladding layer includes a ridge portion disposed in a confronting relationship with the active region. A metallization structure substantially covers the ridge portion and includes at least one layer consisting essentially of titanium nitride.

Titanium nitride diffusion barrier for use in non-silicon technologies and method

A planar, topology free, semiconductor quantum-well laser is described. The quantum-well active layer is formed and patterned in a specified region which is constrained on all sides by high bandgaps which are formed through the use of impurity-free diffusion techniques. After the impurity-free diffusion has taken place, an upper portion is then epitaxially deposited to complete the structure. High-power, single fundamental mode laser operation is achieved by funneling current into the constrained quantum-well active region, high bandgap regions in conjunction with low index of refraction in regions surrounding the active area. The structure is further designed to allow low beam divergence in the direction perpendicular to the semiconductor laser junction.

Semiconductor laser with low vertical far-field

Optical waveguide isolator (121) for monolithic integration with semiconductor light emitting diodes such as Fabry-Perot or ring laser diodes. The present optical isolator (121), with optical input port (95) and output pod (96), comprises a branching waveguide coupler (56). This branching waveguide coupler (56) has a waveguide stem (60) splitted at one end into two waveguide branches (57, 58) such that a light wave fed via said input pod (95) into a first of these branches (58), is guided via the waveguide stem (60) and the output pod (96) out of the device. A light wave fed to the isolator's output pod (96) is guided along the stem (60) and coupled into the second waveguide branch (57).

Optical waveguide isolation

Planar, topology-free, single-mode, high-power semiconductor

Laser diode with independent electronic and optical confinement, referred to as decoupled confinement, comprising an active region, i.e. an active layer, a single quantum well layer or a multi-quantum well layer, embedded in a carrier confinement structure providing for an energy barrier at least on one side of the active region. This energy barrier reduces carrier leakage out of the active region. The carrier confinement structure is embedded in an optical confinement structure which guides the optical light wave. The inventive laser diode is characterized in that the height of the energy barrier confining the carriers, and the refractive index step providing for optical waveguiding of the light wave are decoupled.

Decoupled optic and electronic confinement laser diode

A semiconductor ridge waveguide laser structure with a roughened sidewall ridge that includes a substrate and an active layer disposed between lower and upper cladding layers. The structure further includes a waveguide ridge which comprises a contact layer and a trapezoidal ridge portion 16 of the upper cladding layer. The trapezoidal ridge portion has roughened sidewalls which provides low contact resistance.

Roughened sidewall ridge for high power fundamental mode semiconductor

A protection configuration for a semiconductor ridge waveguide laser structure is disclosed wherein layers of protective metal in the form of walls, is applied on each side of the ridge element of the ridged layer of the laser structure. The laser structure is then bonded to a mounting plate in a junction side down orientation by solder or a junction side up orientation by wire bonding. The metal layer may be composed of gold.

Waveguide ridge laser device with improved mounting and ridge protection

A semiconductor ridge waveguide laser having a high value of horizontal far-field wherein the laser structure includes a substrate, a first or lower cladding layer composed of a AlGaAs on the substrate, an acting layer on the lower cladding layer, and a second or upper cladding layer composed of AlGaAs on the active layer. The upper cladding layer includes a raised ridge portion formed by etching the upper cladding layer through a mask. A contact layer is disposed on top of the ridge portion. The aluminum mole concentration of the lower cladding layer is greater than the aluminum mole concentration of the upper cladding layer. This forces the optical mode towards the upper cladding layer and results in an increased lateral waveguide confinement that produces a high horizontal far-field.

Semiconductor ridge waveguide laser with asymmetrical cladding

A method for full-wafer processing of laser diodes with cleaved facets combining the advantages of full-wafer processing, to date known from processing lasers with etched facets, with the advantages of cleaved facets. The steps being: defining the position of the facets to be cleaved by scribing marks into the top surface of a laser structure comprising epitaxially grown layers, these scribed marks being perpendicular to the optical axis of the lasers to be made, the scribed marks being parallel, their distance (l.sub.c) defining the length of the laser cavities and the distance (l.sub.b) between the facets of neighboring laser diodes; and covering the uppermost portion with an etch mask pattern which provides for etch windows between the scribed marks defining the position of facets of neighboring lasers; and etching trenches into an upper portion of the structure defined by the etch windows; and partly underetching the upper portion during a second etch step such that the laser facets can be defined by cleaving the upper portion along the scribed marks without cleaving the whole laser structure; and ultrasonically or mechanically cleaving the upper portions being underetched along the scribed marks; and separating the laser diodes by cleaving them between neighboring lasers.

Full-wafer processing of laser diodes with cleaved facets

A method for cleaving semiconductor wafers, or segments thereof, which comprises placing the wafer, provided with scribe lines defining the planes where cleaving is to take place, inbetween a pair of flexible transport bands and guiding it around a curved, large radius surface thereby applying a bending moment. With a moment of sufficient magnitude, individual bars are broken off the wafer as this is advanced, the bars having front-and rear-end facets. On cleaving, each bar, while still pressed against the curved surface, is automatically separated whereby mutual damage of the facets of neighboring bars is prevented. For further handling, e.g. for the transport of the bars to an evaporation station for passivation layer deposition, provisions are made to keep the bars separated. Cleaving and the subsequent passivation coating can be carried out in-situ in a vacuum system to prevent facet contamination prior to applying the passivation.

Method for batch cleaving semiconductor wafers and coating cleaved facets

Apparatus and method for producing coherent blue-green-light radiation having a wavelength of essentially 490-500 nm. A diode laser, such as a strained-layer InGaAs/GaAs diode laser, provides a 980-1,000 nm beam, and a nonlinear crystal of KTP produces coherent radiation by noncritically phase-matched second-harmonic generation (SHG) of said beam. The beam preferably has a wavelength of essentially 994 nm for generating radiation having a wavelength of essentially 497 nm. The crystal is disposed within an optical resonator and the frequency of the laser is locked to that of the resonator. Alternatively, two diode lasers are oriented to provide orthogonally polarized beams each with a wavelength of 980-1,000 nm but within essentially 1 nm of each other, and the KTP crystal is oriented with its a- and c-axis parallel to the orthogonally polarized beams. The KTP crystal may have an associated optical waveguide along which the beam is propagated to enhance SHG efficiency.

Miniature blue-green laser source using second-harmonic generation

A process for forming the ridge structure of a self-aligned InP-system, double heterostructure (DH) laser, particularly useful for long wavelength devices as required for signal transmission systems includes a thin Si.sub.3 N.sub.4 layer (41) inserted between a photoresist mask (42) that defines the ridge structure, and a contact layer (35). Using a Si.sub.3 N.sub.4 layer (4) deposited at a high plasma excitation frequency (RF) for adhesion promotion, and a low frequency deposited (LF) Si.sub.3 N.sub.4 layer (43) for device embedding, provides for the etch selectively required in the process step that is used to expose the contact layer to ohmic contact metallization deposition.

Process for forming the ridge structure of a self-aligned semiconductor

An integrated semiconductor structure with optically coupled laser diode (11) and photodiode 12A, both devices having etched, vertical facets (16A, 21). The photodiode has a spatially non-uniform sensitivity profile with respect to the incident light beam (18A) emitted by the laser. This is due to the varying distance from the laser facet and/or to variations in the angle of incidence and results in photocurrents produced by the photodiode that depend on the intensity distribution of the light beam. The spatially non-uniform sensitivity profile allows the measurement of the far-field intensity distribution of the laser and thus on-wafer screening of lasers with respect to their mode stability.

Integrated semiconductor diode laser and photodiode structure

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Zurich, Switzerland

Christoph S Harder