Bell Telephone Laboratories

At&t Bell Laboratories

Agere Systems Inc.

American Telephone & Telegraph Co., At&t Bell Laboratories

Lucent Technologies Inc.

Agere Systems Guardian Corp.

Triquint Technology Holding Co.

Robert Louis Hartman

Louis A Koszi

Bertram Schwartz

David Alan Ackerman

Richard Bendicks Bylsma

Daniel Paul Wilt

Lars E Eng

Thomas L Koch

Andrew H Bobeck

Eugene I Gordon

Lynn Frances Schneemeyer

Stephen A O'Brien

Renato M Camarda

John M Geary

Philip J Anthony

Venkataraman Swaminathan

Gleb E Shtengel

Malcolm Ellis Lines

Norman E Schumaker

Cyril J Mogab

Glen Robert Kowach

Padman Parayanthal

Franklin Richard Nash

Lloyd R Harriott

Wilbur Dexter Johnston, Jr

George J Przybylek

John L Zilko

Daniel R Kaplan

Waleed A Asous

Marc Ilegems

William J Tabor

Magaly Spector

Wilfried R Wagner

Richard S Williams

An improved semiconductor laser (distributed feedback or Bragg reflector laser) is disclosed, having reducing wavelength chirping. In a laser having a substrate, an optical waveguide layer disposed on the substrate with a grating region, and a cladding region disposed on the optical waveguide layer, an isolation region is positioned in at least one of the substrate, optical waveguide layer, and cladding layer. The isolation region is comprised of a material adapted to increase the resistivity of the one or more layers in which it is placed to reduce electrical cross-talk and wavelength chirping. Preferably, the isolation region is positioned in at least the cladding layer, which the inventors have found is the greatest contributor of cross-talk and wavelength chirping.

Apparatus and method for minimizing wavelength chirp of laser devices

The thermo-optic behavior of an optical path over a range of temperatures &Dgr;T is controlled by determining a figure-of-merit (FOM) for the optical path and including in the path a body of crystalline material that enables the conditions specified by the FOM to be satisfied. The crystalline material is highly transparent at a wavelength &lgr; of radiation propagating in the path, and it has a coefficient of thermal expansion (CTE) and a refractive index n such that the CTE and dn/dT are mutually adapted to satisfy the FOM over the range &Dgr;T. In one embodiment, the CTE and dn/dT of an etalon compensate one another so as to perform frequency discrimination that is essentially temperature insensitive over the range &Dgr;T. In a preferred embodiment of the optical etalon the crystalline material comprises LiCaAlF .

Using crystalline materials to control the thermo-optic behavior of an optical path

Optical sources, such as electro-absorption modulator isolated laser modules (EMILMs), for fiber optical communication systems are selected based on noise measures made outside&mdash;and preferably substantially outside&mdash;of the communication system's operational bandwidth. In one embodiment, EMILM devices are selected for communication systems having path lengths of 640 km or more based on both the chirp of the devices and the relative intensity noise (RIN) of the devices at the relaxation oscillation frequency F . Devices having both low chirp and low RIN at F are more likely to meet bit error rate requirements than are devices selected solely for low chirp.

Process for selecting optical sources for communication system

A semiconductor device is provided with at least two photodetectors and an interposed etalon. Signals from the photodetectors may be compared to generate a control signal. The control signal may be used for wavelength control and/or stabilization and for other purposes. According to a preferred embodiment, the etalon is formed of at least two distributed Bragg reflectors. The etalon provides high discrimination power. In addition, the etalon has a periodic discrimination function that may be matched to the periodic channels of a dense wavelength division multiplexing system. According to one aspect of the invention, electrical current may be applied to selected layers of the device to tune and/or shift the response of the device. If desired, the invention may be incorporated into a waveguide structure, such as an optical fiber. The present invention also relates to a wafer fusion technique for making integrated devices.

Semiconductor etalon device, optical control system and method

The invention is a laser with improved turn-on time for digital applications. The low bias capacitance effect of the laser is reduced by use of a buffer region formed between the substrate and the active region, the buffer region having a lower dopant concentration than the substrate.

Uncooled lasers with reduced low bias capacitance effect

A reflection filter is disposed on a solid state laser so as to preferentially reflect TE or TM modes and to suppress oscillation within the resonator of the non-reflected modes. In one embodiment, the filter includes a layer having a plurality of grooves which may be straight and parallel or curved to approximate the mode shape. In another embodiment, the filter includes a polarization sensitive film, without grooves, which either absorbs or transmits the undesired mode. Specifically described is a buried heterostructure semiconductor DFB laser with such a reflection filter formed on at least one facet thereof.

Tranverse mode control in solid state lasers

A nondestructive method is proposed for measuring stripe dimensions in order to grade light-emitting structures such as lasers. The width of the near-field emission parallel to the stripe is measured while the laser is operating below threshold. This measurement is correlated with the actual stripe width and with the possibility of kinks developing in the light output. The width of the far-field emission perpendicular to the junction plane can also be measured, and the product of the two widths can be correlated with the stripe area and the possibility of kinks in the laser output.

Method of manufacturing high-quality semiconductor light-emitting devices

Prior to packaging, semiconductor lasers are purged by being subjected first to high temperature and high current simultaneously so as to suppress stimulated emission and stress the shunt paths which allow leakage current to flow around the active region. A prudent, but nonessential, second step is to lower the temperature and/or current so that the lasers emit stimulated emission (preferably strongly, near the peak output power), thereby stressing the active region. Lasers subjected to such a purge exhibit stabilized degradation rates in short times (of the order of a few hours) and provide a robust population which meets the performance criteria of long lifetime systems.

Purging: a reliability assurance technique for semiconductor lasers

The property of Group III-V compound materials, whereby ion bombarded material becomes highly resistive but recovers its original low resistivity by annealing at a temperature which is dopant and material dependant, is utilized to fabricate integrated circuits which include buried semiconductor interconnections or bus bars between devices.

Production of semiconductor structures with buried resistive or

A method of producing patternable resistive regions in III-V compound semiconductor devices and a resulting device structure having improved current characteristics. III-V semiconductor substrates are irradiated with inert ions to produce a resistive region therein. At least one epitaxial layer is grown over the substrate while maintaining the resistive characteristics within the substrate. A second resistive region is then formed in at least the top epitaxial layer. This second resistive region is aligned with the first one in order to minimize current spread through the device.

Method of improving current confinement in semiconductor lasers by inert

A TJS light emitting diode (laser or LED) comprises an isotype double heterostructure (DH) and a V-groove which penetrates the intermediate layer of the DH. The groove is filled with a region of semiconductor material which enables carrier injection to occur from the region into the intermediate layer, or conversely, depending on the relative bandgaps of the layer and region. Real-refractive index guiding by the groove is described.

Stripe-guide TJS laser

Semiconductor lasers and LEDs are described in which the pumping current is constrained to flow from a relatively narrow upper channel formed by a V-groove, which extends to a depth short of the active region, through a relatively wider lower channel bounded by high resistivity regions, which extend from at least that depth into or through the active region. Also described are devices in which the V-groove is refilled with semiconductor material.

V-Groove semiconductor light emitting devices

A double heterostructure light emitting semiconductor device is described wherein a narrow bandgap active region is sandwiched between two wider bandgap cladding layers, one of which contains a p-n homojunction. The purpose is to separate the p-n junction from the active region and, thus, to have the active region bounded by two isotype (p-p or n-n) heterojunctions. This configuration significantly reduces nonradiative interface recombination current which occurs principally at the anisotype (p-n) heterojunction in a standard double heterostructure.

Light emitting semiconductor devices

A buried double heterostructure laser device isdescribed. A wafer of double heterostructure material is formed into narrow mesa stripes. A native oxide coating is formed on the side walls of the mesa. Semiconductor material having an index of refraction which is closely matched to the index of the active region is deposited over the mesa structure. High resistivity polycrystalline material forms on the native oxide and monocrystalline material forms on the top of the mesa. Vertical carrier and optical confinement is achieved by the higher bandgap cladding layers of the double heterostructure configuration. The native oxide acts as an electrical insulator to confine pumping current to the mesa. The closely matched polycrystalline material confines light parallel to the junction plane and prevents excitation of higher order transverse modes. Devices have been fabricated which exhibit cw threshold currents at room temperature as low as 55 mA.

Buried double heterostructure laser device

Plasma etching is described as a selective etch for dielectric masks such as SiO.sub.2, Si.sub.3 N.sub.4 and certain photoresists in the presence of native oxides of Group III-V compound semiconductors. This process can be used in the fabrication of mesa junction lasers and Burrus light emitting diodes.

Growing community of inventors

Warren Township, NJ, United States of America

Robert Louis Hartman