Gte Laboratories Incorporated

Jia-Ming Liu

Ying C Chen

Robert J Seymour

Ying-Chih Chen

Michael A Newkirk

An optically controlled semiconductor waveguide interferometer apparatus includes a Mach-Zehnder interferometer formed of semiconductor laser materials. A first optoelectronic switching means is adapted to be coupled across a first voltage potential and one of the optical paths of the interferometer. The first optoelectronic switching means has a first gap therein. Likewise, a second optoelectronic switching means is adapted to be coupled across a second voltage potential and the other of the optical paths. The second optoelectronic switching means has a respective gap therein. Light pulses are applied to the two gaps for controlling the index of refraction of the optical paths, whereby the light pulses control the interferometer so that the output intensity of the interferometer is modulated.

Optically controlled semiconductor waveguide interferometer apparatus

A complete set of optical logic gates and circuits based upon direct polarization switching, and various types of optical flip-flops based upon polarization bistability, in semiconductor lasers are described. By operating the laser in the direct polarization switchable mode, logic gates and circuits such as inverter, AND, NAND, OR and NOR can be provided with two optoelectronic switches or photodetectors. With the laser being operated in the polarization bistable mode, clocked optical flip-flops are operable with a few optoelectronic switches or photodetectors.

Optical logic and memory apparatus

An optical square wave multivibrator includes a semiconductor laser that operates near the polarization transition temperature in a pure TM mode at low injection currents and switches operation to a pure TE mode at high injection currents, and vice versa. Near such temperature, the semiconductor laser experiences large hysteresis loops with high contrast ratio in its polarization-resolved power vs current characteristic while total power exhibits only slight change in hysteresis. The switching behavior of the TE mode is complementary to that of the TM mode. The laser is biased within the hysteresis loops. A current pulse applied in one direction to the laser causes it to provide a TE mode laser output, whereas a current pulse applied in the other direction causes the laser to provide a TM mode laser output. Optical delay line means are coupled to the laser so as to be responsive to an initiation of light in a TE mode for causing a current pulse to be applied to the laser to switch it to the TM mode laser output and to be responsive to cessation of light in the TE mode from the laser for causing a current pluse to be applied in one direction to cause the laser to switch to TE mode, thereby resulting in a polarization-bistable square wave output.

Optical multivibrator

The laser device of the present invention comprises: a semiconductor substrate; a first cladding layer of semiconductor formed on the substrate; an active layer of semiconductor formed on the first cladding layer, thereby forming a junction plane between the active layer and the first cladding layer; a second cladding layer of semiconductor formed on the active layer and a cap layer of semiconductor formed on the second cladding layer; the active layer having a lattice constant parallel to the junction plane sufficiently larger than the lattice constant normal to the junction plane so as to increase the optical gain of the TM mode relative to the optical gain of the normally operating TE mode, such that at a first injection current level, the laser device operates in the TM mode and at a second injection current level, the laser device operates in the TE mode. The laser output of the laser device of the present invention can be switched between a pure TM mode and a pure TE mode with nanosecond response time by varying injection current levels of the device.

Fast polarization-switchable semiconductor lasers

An InGaAsP laser structure having a support structure which contains an equal number of buffer layers and substrate layers is provided. The buffer layers of the support structure drastically reduce the tensile stress in the active layer, thereby eliminating the occurrence of undesired TM emission during normal operation. The semiconductor laser device of the present invention comprises: a support structure having one or more substrate layers and one or more buffer layers, the support structure containing an equal number of substrate layers and buffer layers, the substrate layers consisting of InP, the buffer layers consisting of In.sub.1-x' Ga.sub.x' As.sub.y' P.sub.1-y' with x'.perspectiveto.0.47y' and 0&lt;y'.ltoreq.1, one of the substrate layers providing the lower surface of said semiconductor laser device; a first cladding layer of InP formed on the exposed buffer layer of the support structure; an active layer formed on the first cladding layer, the active layer consisting of In.sub.1-x Ga.sub.x As.sub.y P.sub.1-y with x.perspectiveto.0.47y and y.ltoreq.y'.ltoreq.1 and a second cladding layer of InP formed on the active layer; and a cap layer of In.sub.1-x' Ga.sub.x' As.sub.y' P.sub.1-y' with x'.perspectiveto.0.47y' and 0&lt;y'.ltoreq.1 formed on the second cladding layer; the buffer layers, first cladding layer, active layer, second cladding layer, and cap layer being substantially perfectly lattice-matched with the substrate layers at the growth temperature. Preferably, the buffer layers consist of In.sub.0.53 GA.sub.0.47 As.

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Arlington, MA, United States of America

Jia-Ming Liu