DAVID E WELCH
Pilots at Meridian Ave, San Jose, CA

4933301, Jun 12, 1990

Jan 27, 1989

7/303751

Donald R. Scifres - San Jose CA
David Welch - San Jose CA
Peter Cross - Palo Alto CA
William Streifer - Palo Alto CA

Spectra Diode Laboratories, Inc. - San Jose CA

H01L 2120, H01L 21203

437129

A method of making semiconductor laser arrays having an impurity disordered pattern of waveguides at least some of which are directly joined at branching junctions. The region near the branching junctions provides a phase boundary condition in which lightwaves propagating in adjacent waveguides are in phase. Using one impurity dose and one disordering depth in a first portion of the pattern and another in a second portion of the pattern provides a combination of strong and weak waveguiding with strong waveguides that eliminate evanescent coupling from occurring at least in the branching junction regions, and with weak guides near one or both end facets permitting evanescent coupling. The evanescent coupling between adjacent weak waveguides preserves the in phase relationship that was established in the Y-junction regions, resulting in a diffraction limited single lobe far field output. Alternatively, even without evanescent coupling, the modes can adjust their phases in the weak waveguides, where the propagation constant is less tightly specified by the geometry.

5231642, Jul 27, 1993

May 8, 1992

7/880681

Donald R. Scifres - San Jose CA
Kenneth M. Dzurko - Santa Clara CA
Robert G. Waarts - Palo Alto CA
David F. Welch - San Jose CA
Amos Hardy - Mountain View CA
Stephen O'Brien - Sunnyvale CA

Spectra Diode Laboratories, Inc. - San Jose CA

H01S 319

372 45

A semiconductor laser that includes at least one grating reflector with a grating period selected to diffract at a nonperpendicular angle within the plane of the laser waveguide. This allows dispersal of laser light, eliminating filamentary multimode operation of broad area lasers. In one embodiment, the grating reflector couples light between a single transverse mode waveguide portion of the optical cavity and a second, broad area, portion that is not collinear with the single mode waveguide. In another embodiment, the cavity favors a ring mode of oscillation. One or more grating reflectors form part of the feedback mechanism which forms a resonant optical cavity with noncollinear portions. Other reflectors in the feedback mechanism include facet reflectors which can be cleaved or ion milled, or semiconductor material refractive index boundaries. Laser embodiments with two or more grating reflectors can be independently tuned to provide a high rate of amplitude modulation.

5219785, Jun 15, 1993

Jul 25, 1990

7/557901

David F. Welch - San Jose CA
Donald R. Scifres - San Jose CA
William Streifer - Palo Alto CA

Spectra Diode Laboratories, Inc. - San Jose CA

H01L 2100, H01L 2102, H01L 21203, H01L 21265

437129

A method using implantation to form a semiconductor laser or laser array with current blocking implants. A semiconductor material laser structure including layers of a first conductivity type, an active region and layers of a second conductivity type is formed. In a first embodiment, impurity ions of the second conductivity type are implanted into selected regions of a first conductivity type layer. The implanted ions form current blocking buried regions of the second conductivity type with current confining channels therebetween. Finally, the structure is thermally annealed. In a second embodiment, a disorder inducing impurity, which may be a saturable absorber, is diffused into selected portions of the layers of the first conductivity type through the active region. The diffusion converts side regions of those layers into the second conductivity type. Impurity ions of the first conductivity type are implanted to a uniform depth crossing through the side regions to form a buried region of the first conductivity type.

5185752, Feb 9, 1993

Feb 18, 1992

7/837819

David F. Welch - San Jose CA
Robert G. Waarts - Palo Alto CA

Spectra Diode Laboratories, Inc. - San Jose CA

H01S 310

372 22

Arrangements for efficiently coupling light between a laser diode and a second-harmonic generator which feature external resonant cavities that include a feedback grating fabricated on the second-harmonic generator. The feedback grating reflects light of a first frequency that matches the frequency doubling band of the second-harmonic generator, thereby establishing stable laser oscillation at that first frequency. Preferably, the second-harmonic generator has a periodically-poled waveguide formed in the surface of the nonlinear material body. The laser diode may be butted against the harmonic generator or coupling optics may be positioned between the two. In one arrangement, a polarizer is placed in the resonant cavity, either between an external back reflector and the back facet of the laser diode or between the antireflection coated front facet of the laser diode and the harmonic generator, to provide loss to the TE polarization mode and enhance oscillation in the TM polarization mode. In another arrangement, a half-wave plate is positioned between the antireflection coated front facet of the laser diode and the input end of the harmonic generator to cause TE mode oscillation in the laser diode, while coupling TM polarized light into the harmonic generator. The laser diode may be a monolithic laser diode array with multiple emitters, with the second-harmonic generator having multiple waveguides for receiving and doubling the frequency of light received from a corresponding diode emitter.

5003550, Mar 26, 1991

Mar 9, 1990

7/494620

David F. Welch - San Jose CA
Robert G. Waarts - Palo Alto CA
David G. Mehuys - Mountain View CA
Richard R. Craig - San Jose CA

Spectra Diode Laboratories, Inc. - San Jose CA

H01S 319

372 50

A monolithic integrated master oscillator power amplifier (MOPA) device including a single mode diode laser with distributed Bragg reflectors, an amplifier in tandem with the laser, lateral phase controllers and a detuned second order grating surface output coupler, all on a common substrate. The amplifier is a flared waveguide in one embodiment, and a branching network of single mode waveguides followed by an array of single mode gain waveguides in another embodiment. The diode laser is tunable by means of a separate tuning current applied to the rear Bragg reflector. Tuning the laser wavelength provides, in conjunction with the output coupler, a longitudinal steering of the output beam. The lateral phase controllers are an array of separately addressable electrodes that adjust the optical path length to compensate for phase variation in the amplifiers and also to provide lateral steering of the output beam. An additional embodiment includes a chain of amplifiers and grating output couplers for providing multiple output beams.

4845725, Jul 4, 1989

May 20, 1987

7/053093

David F. Welch - San Jose CA
Donald R. Scifres - San Jose CA

Spectra Diode Laboratories, Inc. - San Jose CA

H01S 319

372 46

A window laser having at least one window region with a transparent waveguide layer optically coupled to an active region generating lightwaves. The waveguide layer is characterized by a broader guided transverse mode for the lightwaves than the active region and may have a thickness which is greater than the active region, a refractive index difference with respect to cladding layers which is less than a refractive index difference between the active region and the cladding layers, or both. The waveguide layer may be coupled to the active region via a transition region characterized by a gradual change in the guide mode width of the lightwaves, such as from a tapered increase in thickness of the waveguide layer in a direction away from the active region. The preferred method of making window regions having these transparent waveguides is impurity induced disordering, in which the interfaces between active region and cladding layers is smeared to produce the waveguide layer with increased bandgap and a graded transverse refractive index profile. The laser is characterized by a high power output beam with reduced far field transverse divergence.

5159604, Oct 27, 1992

Jul 29, 1991

7/737463

David G. Mehuys - Sunnyvale CA
Amos A. Hardy - Tel Aviv, IL
David F. Welch - San Jose CA
Robert G. Waarts - Palo Alto CA
Donald R. Scifres - San Jose CA

Spectra Diode Laboratories, Inc. - San Jose CA

H01S 319

372 50

In a semiconductor laser array structure in which antiguided regions between high effective refractive index waveguide regions experience greater gain then the waveguide regions, structures introduced at the sides of the array, next to the edgemost waveguides and not on the array period, reflect laterally transmitted radiation back toward the center of the array. The edge reflecting structures may be waveguide regions having widths of (m'+1/2) half-wavelengths, where "m'" is zero or a positive integer, compared to array waveguides with width m, where "m" is an integer not necessarily equal to "m'". The edge reflecting structures may also be stacks of such waveguides, where the regions between the edge waveguides are of a width substantially equal to (n'+1/2) half-wavelengths, compared to antiguide element widths of n half-wavelengths. The two integers n and n' may be, but are not necessarily, equal. Alternatively, the edge reflectors can be mirrors fabricated at the side edges of the array or by disordering the active region beyond the edgemost waveguides to form a refractive index step.

4751711, Jun 14, 1988

Aug 16, 1985

6/766637

David Welch - San Jose CA
Peter Cross - Palo Alto CA
Donald R. Scifres - San Jose CA

Spectra Diode Laboratories, Inc. - San Jose CA

H01S 319

372 50

A phased array laser having a laterally asymmetric variation in the gain or coupling of lasing elements of the array for emission in a single far field lobe. The lasing elements are confined by internal waveguide structuring, periodically spaced current confinement stripes, or by a hybrid of both waveguiding and current confinement. The widths, lengths, depths, or separations of the waveguides or stripes vary laterally across the array to affect the gain or coupling of the lasing elements. Alternate embodiments introduce lateral asymmetry in the active region or other layer thicknesses, doping, mirror facet reflectivities, A1 content of the layers, heat dissipation, or thicknesses of electrical contacts. The laterally asymmetric variations may be linear or nonlinear, monotonically increase from one edge to the other edge, or may be such that the relevant parameter is greatest or least in the center of the array.

5185754, Feb 9, 1993

Jul 29, 1991

7/737194

Richard R. Craig - Palo Alto CA
David F. Welch - San Jose CA
Erik P. Zucker - Mountain View CA
Donald R. Scifres - San Jose CA
William J. Gignac - Sunnyvale CA

Spectra Diode Laboratories, Inc. - San Jose CA

H01S 319

372 45

A laser diode construction having internal reflectors within the laser cavity to provide a stable spectral mode of laser operation. The laser includes a plurality of contiguous semiconductor layers disposed on a substrate to form a semiconductor body with at least one layer forming an active region. Electrically conductive contacts bias the heterostructure to inject current into the active region and produce lightwaves. Feedback means define two or more tandem resonant optical cavities to achieve lasing operation. The feedback means includes at least one internal light reflector within the semiconductor body. In a preferred embodiment, a pair of spaced apart internal reflectors are provided with the region between the pair also being electrically pumped to define an active internal etalon. Other embodiments have multiple periodic reflectors or combine internal reflectors with feedback gratings or passive windows at the end facets of the body.

5048036, Sep 10, 1991

Jan 4, 1991

7/638358

Donald R. Scifres - San Jose CA
David F. Welch - San Jose CA
John Endriz - Belmont CA
William Streifer - late of Palo Alto CA

Spectra Diode Laboratories, Inc. - San Jose CA

H01S 319, H01L 3300

372 45

Semiconductor heterostructure lasers having at least one lattice mismatched strain layer in the cladding proximate to the active region. Indium or phosphorus may be added in high concentration to form the strain layers. The strain layers may be spaced somewhat apart from the active region or may be adjacent to the active region. In either case, the strain layers decrease transparency current and increase differential gain.