Bell Communications Research, Inc.

Elyahou Kapon

Arie Shahar

Constance J Chang-Hasnain

Robert J Deri

Robert N Thurston

Meir Orenstein

A method of fabricating an array of vertical-cavity, surface-emitting lasers that allows the lasers to be phase-locked and the resulting device. The growth of the laterally unpatterned epitaxial vertical-cavity structure includes an upper mirror which is only partially reflective. A gold layer supplies the final reflectivity. A grip pattern is then etched in the gold layer, and a lower reflectivity metal layer is deposited over the gold layer and into the grid. The lower reflectivity metal both provides a common contact to the laser elements but also degrades the mirror reflectivity in the grid portion. The lower reflectivity prevents the grid portion from lasing. The areas within the grid pattern are separate lasers, but they are so closely separated that they lase coherently among themselves.

Phase-locked array of reflectivity-modulated surface-emitting lasers

A tapered single-mode rib waveguide for which only laterally patterning is required. A sublayer is disposed between the low-index substrate and the high-index rib and has an intermediate index. Preferably a thin buffer layer of very low refractive index is disposed between the rib and the sublayer. The widths of the rib are chosen so that in a wide portion the optical power of the single-mode is concentrated in the rib or buffer layer but in a narrow portion the optical power is concentrated in the sublayer or substrate and additionally has a wide lateral distribution. A similar effect can be obtained by tapering an upper rib disposed on top of an untapered lower rib.

Tapered rib waveguides

A novel quantum-well semiconductor is described wherein the quantum well is formed by growing a thin (.ltoreq.500 .ANG.) epitaxial layer on a patterned (e.g. grooved) non-planar substrate so as to achieve thickness variations along the quantum well and hence laterally varying superlattice periodicity and QW depth. Using this structure one can achieve lateral carrier confinement and real refractive index waveguiding. Index-guided GaAs/AlGaAs lasers are described.

Semiconductor superlattice heterostructures on non-planar substrates

A novel quantum well semiconductor is described wherein the quantum well is formed by growing a thin (.ltoreq.500 .ANG.) epitaxial layer on a patterened (e.g. grooved) non-planar substrate so as to achieve thickness variations along the quantum well and hence laterally varying superlattice periodicity and QW depth. Using this structure one can achieve lateral carrier confinement and real refractive index waveguiding. Index guided GaAs/AlGaAs lasers are described.

Semiconductor superlattice heterostructures on nonplanar substrates

A low loss optical waveguide modulator, an essential component of opto-electronic integrated circuits which can combine optical and electronic devices on a single chip optical communication systems is described. The modulator in our embodiment consists of a sequence of epitaxial layers on a single crystal substrate consisting of a n.sup.+ -GaAs substrate, a n.sup.+ -GaAs buffer layer, a n-Al.sub.0.05 Ga.sub.0.95 As electrode layer, an effective i-Al.sub.0.25 Ga.sub.0.75 As confinement layer, an i-GaAs guiding layer, an effective i-Al.sub.0.25 Ga.sub.0.75 As confinement layer, a p-Al.sub.0.25 Ga.sub.0.75 As electrode layer and a p.sup.+ -GaAs cap layer. The layers have an index of refraction profile such that the index of refraction of the confinement layers are substantially less than the index of refraction of the guiding layer and the index of refraction of the first electrode layer is substantially greater than the index of refraction of the first confinement layer.

Low loss semiconductor optical phase modulator

A cross-coupled stripe laser array in which a substrate is formed with parallel grooves extending part way across the substrate and an area adjacent interior ends of the grooves is left planar. The orientations of the substrate and the grooves are chosen so as to produce differential epitaxial growth rates between the areas overlying the grooves and the area overlying the planar portion. A vertically confining optical structure is then deposited over both the grooved and planar portions. The structure includes a quantum well region, the bandgap of which depends upon its thickness. Electrical contacts are applied over the grooved regions. Thereby, the lasers overlying the grooves lase at a wavelength to which the equivalent structure overlying the planar portion is transparent, thus providing coupling between the stripe lasers.

Cross-coupled quantum-well stripe laser array

A polarizing optical waveguide comprising a birefringent core surrounded by an isotropic medium wherein the dielectric constant of the birefrigent medium is .epsilon..sub.TE for the plane of polarization parallel to the surface of the medium and .epsilon..sub.TM for the plane of polarization perpendiuclar to this surface and the dielectric constant of the isotropic medium is .epsilon..sub.i. In order to selectively confine the TE mode, the relationship between the dielectric constants is .epsilon..sub.TM &lt;.epsilon..sub.i &lt;.epsilon..sub.TE.

Polarizing optical waveguides

An optical waveguide junction including a multimode input waveguide and a plurality of n spaced apart output waveguides, disposed on a substrate. Each of the output waveguides has a different propagation constant, (e.g., by having different widths or indices of refraction), so that the input modes of optical radiation are sorted in a predetermined way into n groups of output modes corresponding to the n output waveguides. If the input waveguide is excited with optical radiation of different wavelengths, the output waveguides may be tailored with specific widths and indices of refraction to sort the input radiation into the n output waveguides as a function of wavelength, thereby demultiplexing the input optical signal. More generally, the junction may also be utilized with m input waveguides and n output waveguides to implement routing, switching, modulation, and wavelength multiplexing/demultiplexing.

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Old Bridge, NJ, United States of America

Elyahou Kapon