Bell Telephone Laboratories

At&t Bell Laboratories

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

Ralph A Logan

Won-Tien Tsang

Franz Karl Reinhart

James Logan Merz

Henryk Temkin

Charles H Henry

Tawee Tanbun-ek

Harry Gregory White

Federico Capasso

Albert Lee Hutchinson

Barry Franklin Levine

Clyde G Bethea

Daniel P Wilt

William Robert Sinclair

Gerald J Dolan

Disclosed is a graded index separate confinement heterostructure quantum well (GRIN-SCH QW) laser with continuously graded, substantially index matched InGaAsP confinement layer. The inventive device is well adapted for high power output in the wavelength region 1.2-1.68 .mu.m. In particular, it can readily be designed to have an output wavelength that makes it suitable as pump source for Er-doped optical fiber amplifiers. A method of manufacturing a laser according to the invention is also disclosed.

InP-based quantum-well laser

Described is a method for forming epitaxial films comprising successive layers of at least ternary and at least quaternary III-V material grown by metalorganic vapor-phase epitaxy. Between the steps of growing successive layers, the growth chamber is first flushed, advantageously in successive steps using a pair of gaseous Group V hybrides, a few monolayers of binary III-V material are then deposited, and then the growth chamber is again flushed. As a result, interfaces are sharper and interfacial defects are reduced. Also described are quantum well lasers made according to the inventive method.

Method for forming a heteroepitaxial structure, and a device

A buried-heterostructure distributed feedback laser is described, including a grating structure at a surface of a nonplanar cladding layer. The grating structure can be made by transfer of a pattern by ion milling, the pattern being defined in an ion-beam resist layer, e.g., by direct-writing electron-beam exposure. Low-threshold, high-power lasers are obtained with a commercially favorable yield.

Method of making a nonplanar buried-heterostructure distributed-feedback

A double active layer semiconductor laser having single longitudinal mode operation is described. The laser comprises first and second active layers which are separated from each other by an intermediate barrier layer but are optically coupled to each other so that, effectively, single mode operation results.

Double active layer semiconductor laser

A method of making a ridge waveguide laser with the ridge being grown through a stripe opened in an oxide layer covering one of the cladding layers is described. In one embodiment, the cladding layer is corrugated and the ridge waveguide laser is a distributed feedback laser.

Method of making heteroepitaxial ridge overgrown laser

A buried heterostructure laser which obtains lowest mode operation by larger differences in loss between the lowest and higher order modes is described. The loss is achieved by interface scattering between the mesa and the burying layer. The scattering losses increases with refractive index discontinuity, interface roughness and decreasing mesa width. Stabilization results because scattering losses increase rapidly with the order of the transverse modes.

Method of making a loss stabilized buried heterostructure laser

A buried heterostructure laser which obtains lowest mode operation by larger differences in loss between the lowest and higher order modes is described. The loss is achieved by interface scattering between the mesa and the burying layer. The scattering losses increase with refractive index discontinuity, interface roughness and decreasing mesa width. Stabilization results because scattering losses increase rapidly with the order of the transverse modes.

Loss stabilized buried heterostructure laser

A lateral selective area liquid phase epitaxy method useful for the fabrication of, for example, a double barrier buried heterostructure laser, is described.

Method for selective area growth by liquid phase epitaxy

A photodetector useful between 1.0 and 1.6 microns and having an InGaAs layer with an adjacent InGaAsP p-n junction disposed on the InGaAs layer is described.

Photodiode having an InGaAs layer with an adjacent InGaAsP p-n junction

A double heterostructure laser having a pair of opposite-conductivity-type, wide bandgap cladding layers separated by a narrower bandgap active region is characterized in that the active region includes a low-loss waveguide layer and contiguous therewith a narrower bandgap active layer in the form of a narrow strip which extends along the longitudinal (resonator) axis of the laser. Suitable lateral current confinement means, such as reversed biased p-n junctions, are provided to constrain pumping current to flow in a narrow channel through the active layer. Lasers of this type exhibit relatively high pulsed power outputs (e.g., 400 mW), linear L-I characteristics, stable fundamental transverse mode and single longitudinal mode oscillation. In another embodiment the surfaces of the waveguide layer adjacent the active layer are provided with distributed feedback gratings. Also described are techniques for shaping the active layer without the introduction of debilitating defects therein, as well as procedures for LPE growth on Al-containing Group III-V compound layers which are exposed to processing in the ambient.

Strip buried heterostructure laser

The use of gallium arsenide as an electronic material is increasing in popularity. However, its utility for planar MOS technology is hindered by the fact that its native oxide stabilizes upon heating and becomes etch resistant. I have discovered that it is the vaporization of arsenic containing compounds in the oxide which renders the oxide insoluble. A technique is described wherein an inert capping layer is disposed on a layer of the native oxide prior to heat exposure. This prevents evaporation of arsenic, and both the capping layer and the oxide are capable of subsequent dissolution in a weak acid or base.

Oxide masking of gallium arsenide

Described is a method for fabricating a stripe geometry double heterostructure (DH) junction laser in which lateral current confinement is acheived by pairs of laterally spaced, reverse-biased p-n junctions. A mesa is formed on an n-GaAs substrate, for example, and a layer of p-AlGaAs is then grown by LPE so that nucleation does not occur on the top of the mesa. Laterally spaced zones of p-AlGaAs are thus formed on either side of the mesa. An n-p-p or n-n-p DH is then grown so that the interface between the p-AlGaAs layers and the first n-layer of the DH forms a pair of laterally spaced p-n junctions separated by the mesa. When the light-emitting p-n junction in the DH active region is forward biased, the air of spaced junctions are reverse biased so that pumping current is constrained to flow through the active region in a narrow channel to the mesa. Further lateral current confinement is achieved by forming on the upper DH surface a second air of reverse biased p-n junctions separated by a window in alignment with the mesa.

Method for fabricating junction lasers having lateral current confinement

Described is a stripe geometry double heterostructure (DH) junction laser in which lateral current confinement is achieved by pairs of laterally spaced, reverse-biased p-n junctions. A mesa is formed on an n-GaAs substrate, for example, and a layer of p-AlGaAs is then grown by LPE so that nucleation does not occur on the top of the mesa. Laterally spaced zones of p-AlGaAs are thus formed on either side of the mesa. An n-p-p or n-n-p DH is then grown so that the interface between the p-AlGaAs layers and the first n-layer of the DH forms a pair of laterally spaced p-n junctions separated by the mesa. When the light-emitting p-n junction in the DH active region is forward biased, the pair of spaced junctions are reverse biased so that pumping current is constrained to flow through the active region in a narrow channel to the mesa. Further lateral current confinement is achieved by forming on the upper DH surface a second pair of reverse biased p-n junctions separated by a window in alignment with the mesa.

Lateral current confinement in junction lasers

A dual beam laser incorporates a tapered layer within the optical cavity of a GaAs-AlGaAs double heterostructure laser. Dual output waveguides are therefore provided at one of the mirrors. By suitable variations of layer thickness and/or composition, the device operates either as a tapered power divider (TPD), branching the incident power of a single mode into the two output arms of the device, or as a tapered mode splitter (TMS), diverting different transverse modes into different arms. Because the different modes of the TMS have different thresholds, the laser can be pulsed with current pulses of different amplitude to control at which of the waveguides an output appears. The TPD, on the other hand, has coupled cavities which tend to suppress all but one dominant longitudinal mode. Also described is an integrated optical circuit embodiment of the TPD in which the resonator is formed by etched mirrors.

Growing community of inventors

Morristown, NJ, United States of America

Ralph A Logan