Abstract: A double heterostructure opto-electronic device capable of both electronic and photonic switching is described.

Abstract: High-power, single transverse mode laser operation is achieved in an extended-cavity structure by combining a semiconductor gain medium having a large optical cavity together with a length of single mode optical fiber between first and second reflector surfaces. The first reflector surface is formed on an end facet of the semiconductor gain medium; the second reflector surface is formed on an end of the optical fiber. Output power is efficiently coupled from the fiber end of the extended-cavity laser to a standard transmission medium.

Abstract: A process for creating bipolar and CMOS transistors on a p-type silicon substrate is disclosed. The silicon substrate has a typical n+ buried wells and field oxide regions to isolate the individual transistor devices. In accordance with the process, stacks of material are created over the gate elements of the CMOS devices and over the emitter elements of the bipolar transistors. The stacks of material over the gate elements have a silicon dioxide gate layer in contact with the epitaxial layer of the substrate, and the stacks of material over the emitter elements have a polycrystalline silicon layer in contact with the epitaxial layer. Walls of silicon dioxide are created around the stacks in order to insulate the material within the stacks from the material deposited outside of the walls. Polycrystalline silicon in contact with the epitaxial layer is deposited outside the walls surrounding the stacks.

Abstract: A method of fabricating a field-effect transistor is disclosed wherein only two masking steps are used in the development of the device. The semiconductor wafer used in the process has a non-alloyed contact at its top surface, that is, a contact which does not require alloying temperatures in excess of 200 degrees C. The first mask is used to create conventional mesa structures which isolate each individual field-effect transistor from its adjacent neighbors. A second mask is utilized to define the source and drain electrodes and also to create a gap through which the gate electrode structure is fabricated. By using a single mask for creation of both the source and drain electrodes and the gate structure, very close tolerances are obtained between the gate structure and the source and drain regions.

Abstract: Semi-insulating epitaxial layers of Group III-V based semiconductor compounds are produced by an MOCVD process through the use of bis arene titanium sources, such as cyclopentadienyl cycloheptatrienyl titanium and bis (benzene) titanium.

Abstract: Local area networks having a plurality of stations connected to a transmission medium in a daisy chain configuration at the nodes or endpoints experience difficulty in detecting collisions between signals transmitted from two or more stations using standard Manchester violation or lost carrier collision detection techniques. The present invention eliminates collision detection problems in this environment almost entirely by monitoring the signal level coupled from the transmission medium to each station of the daisy chain to detect the presence or absence of collisions and generating a collision detection output signal when the signal level being monitored exceeds a predetermined threshold level.

Abstract: High resistivity Ti-doped Group III-V-based MOCVD layers are used to constrain current to flow through the active region of a variety of devices such as CSBH and DCPBH lasers.

Abstract: Epitaxial regrowth by vapor phase epitaxy of controlled composition semiconductor material in and around undercut regions of a processed heterostructure wafer permits formation of a ridge waveguide capable of active or passive operation. Subsequent material selective and crystallographically preferential etching is employed to form mirror facets on each end of the ridge waveguide.

Abstract: Optical apparatus is disclosed wherein narrow line width light from a source is directed through the substrate of a semiconductor structure and reflected from the gate electrode of a field effect transistor element fabricated on the surface of the semiconductor structure. A quantum well layer serves as the current channel for the field effect transistor, and charge carries from a doped semiconductor layer provide high mobility carriers in the quantum well layer. Changes in the potential between the gate and source electrodes of the field effect transistor causes the normal pinchoff of carriers in the quantum well layer thereby causing changes in the absorption characteristic presented by the quantum well layer.

Abstract: Low loss semiconductor waveguides for supporting propagation of optical signals over a wide range of wavelengths are achieved by growing at least two epitaxial layers of dopant material contiguous along a major surface of each layer to form a heterointerface therebetween. At least one of the epitaxial layers includes a sufficient concentration of semiconductor material to cause strain via lattice mismatch substantially at and near the heterointerface. The strain induces a change in refractive index such that the heterointerface exhibits a substantially higher refractive index than a portion of each epitaxial layer proximate to the heterointerface. The resulting waveguide is capable of supporting propagation of optical signals substantially along the heterointerface. In one example, contiguous epitaxial layers of InP and InGaP form a waveguide for optical signals at wavelengths greater than 0.93 .mu.m. The concentration of Ga in the InGaP epitaxial layer is varied from 10.sup.18 to 10.sup.20 cm.sup.

Abstract: An optical filter using first and second grating sections separated by a changed refractive index section operates as a narrowband grating resonator.

Abstract: In response to ultrafast optical signal pulses, it is now possible to generate correspondingly ultrafast electrical signal pulses by employing semiconductor apparatus including at least one quantum well layer electrically biased by a static electric field. Optical signal pulses incident on the quantum well are at a wavelength substantially less than the absorption edge of the quantum well layer or layers. In other words, the incident optical pulses have a means photon energy less than the bandgap energy of the quantum well layer or layers. The electrical signal pulse generated subsists for a period of time substantially equal to the duration of the optical signal pulses incident on the quantum well layer or layers.

Abstract: A grating in the upper reflecting layer (103 or 203) of an antiresonant reflecting optical waveguide is used to extract energy of a selected wavelength from the waveguiding layer (102 or 202) into the reflecting layer. In one embodiment the reflecting layer (103) is designed as a gain medium which is pumped in the region of a grating (120) and optically terminated at each end of the device such that the embodiment serves as a laser having a long cavity provided by the waveguiding layer (102) with the gain provided in the short grating region. In a second embodiment the reflecting layer (203) in the region of a grating (211) has an opposite conductivity dopant from that of the waveguiding layer (202) such that the device in this region may be backbiased to serve as a wavelength selective photodetector. By placing two wavelength photodetectors in tandem with gratings (211 and 212)of different pitches a wavelength demultiplexing photodetector is provided.

Abstract: Narrow band, wavelength selective optical coupling is achieved in a device including first and second optical transmission media and a filter. The first and second optical transmission media are in substantially close proximity of each other in a predetermined interaction region to provide evanescent coupling therebetween. The filter is positioned on the first optical transmission medium in the predetermined region for causing the coupling to be wavelength selective and contradirectional from the first optical transmission means to the second optical transmission means. One exemplary embodiment of the coupler includes optical fibers as the transmission media and a Bragg reflection grating integrally formed on the first transmission medium as the filter. Other embodiments include the use of semiconductor waveguides as the optical transmission media.

Abstract: Pulses from a first laser source (10) at a predetermined high repetition rate are passed through an isolator (38), a mode-matched with an amplifier and then temporally multiplexed to a predetermined high repetition rate. The high repetition rate pulses (63) are then injected into a second source (70) where they are amplified to derive a stream (79) of high power pulses at the predetermined high repetition rate and then selectively released.

Abstract: An external mirror is positioned relative to the output mirror of a laser to form a Fabry-Perot cavity. The light transmitted by this Fabry-Perot cavity is compared to a reference value in order to develop an error signal which in turn is used to adjust the transmission characteristics of the Fabry-Perot cavity. In the embodiment constructed a beam splitter is positioned to deflect light coupled out of the Fabry-Perot cavity to an optical detector. The output of this detector is compared to a reference voltage in a difference amplifier which generates an electrical error signal. The electrical error signal is coupled to a piezoelectric translator which is attached to the external mirror and is capable of moving that mirror in a way so as to change the transmission characteristics of the Fabry-Perot cavity. Specific embodiments using a dye laser and a soliton laser are also disclosed.

Abstract: Optical functions such as Q-switching, mode locking, cavity dumping, and modulation are generated by a simple laser arrangement which includes a gain medium and an electrically controllable, optical waveguide device optically coupled to the gain medium. The gain medium and waveguide device are either interposed between two reflective surfaces or coupled by a waveguide in order to form a single composite cavity laser structure.

Abstract: A short pulse laser is described which has saturable absorption, saturable gain, group velocity dispersion, and self phase modulation means within a single optical cavity.

Abstract: Epitaxial regrowth by vapor phase epitaxy of controlled composition semiconductor material in and around undercut regions of a processed heterostructure wafer permits formation of a ridge waveguide capable of active or passive operation. Subsequent material selective and crystallographically preferential etching is employed to form mirror facets on each end of the ridge waveguide.

Abstract: Apparatus for measuring the voltage waveform on the metallization lines of an integrated circuit is described. Short high powered pulses of light are coupled from a laser and focused on the metallization line of the integrated circuit which is coupled to receive a voltage waveform that is synchronized to the output laser pulses. Electrons are emitted from the metallization line due to the multiphoton photoelectronic effect induced by the pulses of light. An electron energy analyzer having a uniform extraction grid as its most remote element is positioned with the extraction grid as close as possible to the integrated circuit and the laser pulses are focused through one of the holes of this uniform grid. An output circuit is connected in a feedback arrangement which receives the output pulses of the energy analyzer and develops a voltage on a second uniform grid called the retarding grid that is positioned a predetermined distance from the extraction grid inside the electron energy analyzer.