At&t Bell Laboratories

Lucent Technologies Inc.

Niloy K Dutta

George J Zydzik

Erdmann F Schubert

John Lopata

Paul R Berger

Alfred Yi Cho

Deborah Lee Sivco

Steven K Korotky

Daryoosh Vakhshoori

William Scott Hobson

Henry M O'Bryan, Jr

Dennis G Deppe

Neil E Hunt

Thirumala R Halemane

Li-Wei Tu

Matthias Passlack

Russell J Fischer

An optoelectronic lII-V or II-VI semiconductor device comprises a thin film coating with optical characteristics providing low midgap interface state density. A field effect device for inversion channel applications on III-V semiconductors also comprises a thin dielectric film providing required interface characteristics. The thin film is also applicable to passivation of states on exposed surfaces of electronic III-V devices. The thin film comprises a uniform, homogeneous, dense, stoichiometric gallium oxide (Ga.sub.2 O.sub.3) dielectric thin film, fabricated by electron-beam evaporation of a single crystal, high purity Gd.sub.3 Ga.sub.5 O.sub.12 complex compound on semiconductor substrates kept at temperatures ranging from 40.degree. to 370.degree. C. and at background pressures at or above 1.times.10.sup.-10 Torr.

Gallium oxide coatings for optoelectronic devices using electron beam

The disclosed tunable (wavelength and/or focal length) laser typically is a surface emitting laser that comprises a multilayer structure that comprises the lower Bragg reflector and the active region. A layer of electro-optic material (typically liquid crystal material) is in contact with the top surface of the multilayer structure, and means are provided for applying a voltage across the layer of electro-optic material. In one exemplary embodiment, the layer is inside the laser cavity, making the laser wavelength tunable. In another exemplary embodiment the laser is a Z-laser that focuses the output radiation, with the multilayer structure comprising also the upper Bragg reflector. In this embodiment the layer of electro-optic material is outside the laser cavity, and the laser has tunable focal length. A still further embodiment is both wavelength- and focal length-tunable. Lasers according to the invention can be advantageously used in a variety of applications, e.g., in a wavelength division multiplexed and/or optically amplified optical fiber communication system.

Article comprising a tunable semiconductor laser

This invention pertains to a p-i-n In.sub.0.53 Ga.sub.0.47 As photodiode having an optically transparent composite top electrode consisting of a thin semitransparent metal layer from 10 to 40 nm thick and a transparent cadmium tin oxide (CTO) layer from 90 to 600 nm thick. The metal layer makes a non-alloyed ohmic contact to the semiconductor surface, acts as a barrier between the semiconductor and the CTO preventing oxidation of the semiconductor from the O.sub.2 in the plasma during reactive magnetron sputtering of the CTO layer, and prevents formation of a p-n junction between the semiconductor and CTO. The CTO functions as the n or p contact, an optical window and an anti-reflection coating. The top electrode also avoids shadowing of the active layer by the top electrode, thus allowing greater collection of incident light. Since the top electrode is non-alloyed, inter-diffusion into the i-region is not relevant, which avoids an increased dark current.

P-I-N photodiodes with transparent conductive contacts

This invention pertains to buried heterostructure lasers which have been fabricated using a single step MOCVD growth of an MQW laser structure over a pattern etched GaAs substrate. The wet chemical etching of grooves having a dovetailed cross-section and being parallel to the [011] direction in GaAs substrates produced reentrant mesas which resulted in isolated laser active regions buried by the AlGaAs cladding layer. The 250 .mu.m long uncoated lasers emit at about 1 .mu.m. Lasers with coated facets have threshold currents of 20 mA and emit &gt;100 mW per facet under room temperature operation. The external differential quantum efficiency for currents of from 30 mA to about 50 mA is found to be nearly independent of temperature in the range of 10.degree. C. to 90.degree. C. suggesting a low temperature dependence of leakage current.

Buried heterostructure lasers using MOCVD growth over patterned

This invention embodies a Vertical Cavity Surface Emitting Laser with a top mirror comprising at least one pair of quarterwave layers, each pair consisting of a low index of refraction layer and a high index of refraction layer, the high index of refraction layer being a semiconductor chosen from GaP and ZnS and the low index of refraction layer being chosen from borosilicate glass (BSG) CaF.sub.2,MgF.sub.2 and NaF. Especially useful in vertical cavity surface emitting lasers are mirrors formed by a stack of a plurality of pairs of GaP/BSG or ZnS/CdF.sub.2. Such mirrors have a high reflectivity characteristics required for an efficient operation of the laser. The GaP/BSG or ZnS/CaF.sub.2 mirror structure represents a considerable improvement over previous designs for VCSELs in terms of ultimate reflectivity, low loss, and post growth processing compatibility.

Optical devices with electron-beam evaporated multilayer mirror

Briefly, in the invention a photodetector and an optical amplifier are integrated in the same semiconductor chip. The optical amplifier and the photodetector are positioned side-by-side on the same chip. A portion of the electromagnetic energy carried in the evanescent tail of the optical mode is detected by the photodetector for monitoring the average output power of the optical amplifier. Current confinement and lateral index guiding can be provided by Fe or Ti doped semi-insulating layers of InP. The side-by-side arrangement enables the detector to monitor the output power of the optical amplifier without degrading the output power of the optical amplifier.

Optical amplifier-photodetector assemblage

Briefly, in the invention a photodetector and an injection laser are monolithically integrated on the same semiconductor chip. The laser and photodetector are positioned side-by-side and the laser mirrors can be formed by cleaving. In operation, a portion of the electromagnetic energy carried in the evanescent tail of the optical mode is detected by the photodetector for monitoring the average output power of the laser. Current confinement and lateral index guiding can be provided by Fe or Ti doped semi-insulating layers of InP. The side-by-side arrangement enables the photodetector to monitor the output power of the laser without degrading the output power.

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Colonia, NJ, United States of America

Niloy K Dutta