Abstract: A multi-stage cooler is formed from monolithically integrated thermionic and thermoelectric coolers, wherein the thermionic and thermoelectric coolers each have a separate electrical connection and a common ground, thereby forming a three terminal device. The thermionic cooler is comprised of a superlattice barrier surrounded by cathode and anode layers grown onto an appropriate substrate, one or more metal contacts with a finite surface area deposited on top of the cathode layer, and one or more mesas of different areas formed by etching around the contacts to the anode layer. The thermoelectric cooler is defined by metal contacts deposited on the anode layer or the substrate itself. A backside metal is deposited on the substrate for connecting to the common ground.

Abstract: A heterostructure thermionic cooler and a method for making thermionic coolers, employing a barrier layer of varying conduction bandedge for n-type material, or varying valence bandedge for p-type material, that is placed between two layers of material. The barrier layer has a high enough barrier for the cold side to only allow “hot” electrons, or electrons of high enough energy, across the barrier. The barrier layer is constructed to have an internal electric field such that the electrons that make it over the initial barrier are assisted in travel to the anode. Once electrons drop to the energy level of the anode, they lose energy to the lattice, thus heating the lattice at the anode. The barrier height of the barrier layer is high enough to prevent the electrons from traveling in the reverse direction.

Abstract: The present invention provides a vertical cavity surface emitting laser having high gain and high reflectivity in the desired wavelength range and good thermal and electrical conductivity. The laser structure is comprised of a first mirror region, a second mirror region, and an active region positioned between the first and second mirror regions. Unlike, prior VCSELs, the active region is fused to both the first mirror region and the second mirror region. This allows the laser designer to optimize laser performance for the desired wavelength range by allowing the choice of different materials for the first mirror region, the second mirror region, and the active region.

Abstract: Buried layers are formed within a semiconductor. Metallic or insulating buried layers are produced several microns within a semiconductor substrate. The buried layer can confine current to the buried layer itself by using a conductive material to create the buried layer. The buried layer can also confine current to a specified area of the semiconductor, by using an insulating material inside of the buried layer or by leaving a created void within the material. The buried layer is useful in the construction of a semiconductor Vertical Cavity Laser (VCL). A buried isolation layer confines the current to a narrow active region increasing efficiency of the VCL. The buried layer is also useful in fabricating discrete devices, such as diodes, transistors, and photodetectors, as well as fabricating integrated circuits.

Abstract: A method of processing semiconductor films and layers, utilizing heterojunctions, to create a photodetector. Novel combinations of materials, such as silicon and indium gallium arsenide (InGaAs) are combined using wafer fusion techniques to create heterojunctions that cannot be created by any other growth methods. Devices responsive to different regions of the optical spectrum or that have higher efficiencies are created.

Abstract: By using wafer fusion, various structures for photodetectors and photodetectors integrated with other electronics can be achieved. The use of silicon as a multiplication region and III-V compounds as an absorption region create photodetectors that are highly efficient and tailored to specific applications. Devices responsive to different regions of the optical spectrum, or that have higher efficiencies are created.

Abstract: By using wafer fusion, various structures for photodetectors and photodetectors integrated with other electronics can be achieved. The use of silicon as a multiplication region and III-V compounds as an absorption region create photodetectors that are highly efficient and tailored to specific applications. Devices responsive to different regions of the optical spectrum, or that have higher efficiencies are created.

Abstract: A heterostructure thermionic cooler and a method for making thermionic coolers, employing a barrier layer of varying conduction bandedge for n-type material, or varying valence bandedge for p-type material, that is placed between two layers of material. The barrier layer has a high enough barrier for the cold side to only allow "hot" electrons, or electrons of high enough energy, across the barrier. The barrier layer is constructed to have an internal electric field such that the electrons that make it over the initial barrier are assisted in travel to the anode. Once electrons drop to the energy level of the anode, they lose energy to the lattice, thus heating the lattice at the anode. The barrier height of the barrier layer is high enough to prevent the electrons from traveling in the reverse direction.

Abstract: By using fusion of a heat spreader layer, a large bandwidth, high power semiconductor laser can be fabricated. The use of multiple metals with low thermal resistance allows for higher power because heat flow is conducted away from the active region easily. The extraction of heat from the active region makes the resultant laser more stable with the capability for higher power outputs.

Abstract: Optically flat cleaved facet mirrors are fabricated in GaN epitaxial films grown on sapphire by wafer fusing a GaN film with a sapphire substrate to a cubic substrate such as an InP or GaAs substrate. The sapphire substrate may then partially or entirely removed by lapping, dry etching, or wet etching away a sacrificial layer disposed in the interface between the sapphire substrate and the GaN layer. Thereafter, the cubic InP or GaN substrate is cleaved to produce the cubic crystal facet parallel to the GaN layer in which active devices are fabricated for use in lasers, photodetectors, light emitting diodes and other optoelectronic devices.

Abstract: Buried layers are formed within a semiconductor. Metallic or insulating buried layers are produced several microns within a semiconductor substrate. The buried layer can confine current to the buried layer itself by using a conductive material to create the buried layer. The buried layer can also confine current to a specified area of the semiconductor, by using an insulating material inside of the buried layer or by leaving a created void within the material. The buried layer is useful in the construction of a semiconductor Vertical Cavity Laser (VCL). A buried isolation layer confines the current to a narrow active region increasing efficiency of the VCL. The buried layer is also useful in fabricating discrete devices, such as diodes, transistors, and photodetectors, as well as fabricating integrated circuits.

Abstract: A heterostructure thermionic cooler and a method for making thermionic coolers, employing a barrier layer of varying conduction bandedge for n-type material, or varying valence bandedge for p-type material, that is placed between two layers of material. The barrier layer has a high enough barrier for the cold side to only allow "hot" electrons, or electrons of high enough energy, across the barrier. The barrier layer is constructed to have an internal electric field such that the electrons that make it over the initial barrier are assisted in travel to the anode. Once electrons drop to the energy level of the anode, they lose energy to the lattice, thus heating the lattice at the anode. The barrier height of the barrier layer is high enough to prevent the electrons from traveling in the reverse direction.

Abstract: The mode-locked laser with improved pulse power output can be realized by combining an optical oscillator with a flared CW or modulated gain amplifier. An optical filter or isolator may be disposed between the oscillator and amplifier to avoid feedback of spontaneous noise. A two-segment laser is devised by providing a flared gain section between a modulated gain section and an absorber section within the integrated semiconductor laser. The flared section may taper from a larger modulated gain section to a smaller cross section absorber section or vice versa. Various combinations of absorber sections coupled to modulated gain sections by CW gain or passive flared gain sections may be combined with various arrangements of reflectors and tapered CW gain amplifiers are cascades of such amplifiers and modulated gain pairs.

Abstract: The mode-locked laser with improved pulse power output can be realized by combining an optical oscillator with a flared CW or modulated gain amplifier. An optical filter or isolator may be disposed between the oscillator and amplifier to avoid feedback of spontaneous noise. A two-segment laser is devised by providing a flared gain section between a modulated gain section and an absorber section within the integrated semiconductor laser. The flared section may taper from a larger modulated gain section to a smaller cross section absorber section or vice versa. Various combinations of absorber sections coupled to modulated gain sections by CW gain or passive flared gain sections may be combined with various arrangements of reflectors and tapered CW gain amplifiers are cascades of such amplifiers and modulated gain pairs.

Abstract: A single mode optical fiber switch having a base (70) and a laterally slidable top (91). The base is composed of a quartz block (70) with a slight radius of curvature along its length supporting a silicon substrate (66) having a plurality of parallel v-grooves (68). The grooves are fitted with single mode optical fiber segments (64) and lapped to create a flat coupling surface (82) extending laterally across the base. The top (91) is composed of a quartz block with a single v-groove (93) holding a segment of single-mode fiber (95). This fiber (95) is lapped to create a flat coupling surface matable with the coupling surface on the base. The base (70) and top (91) are placed together such that the top fiber (95) may be selectively slid into and out of coupling alignment with any of the fibers (64) in the base (70) to form a discretely variable delay line. A single length of fiber (121) is wrapped around the base ( 70) in helical fashion with each loop being secured in one of the v-grooves (68).

Abstract: A continuously variable optical delay line having a first substrate (66, 70) and a second substrate (95). The first substrate is composed of a quartz block (70) with a large radius of curvature along its length, supporting a silicon substrate (66) having a plurality of longitudinal, parallel v-grooves (68). A single length (121) of single mode optical fiber is wrapped around the first substrate (66, 70) in helical fashion with each loop being secured in one of the v-grooves (68). The portions of the fiber (121) in the v-grooves (68) are lapped and polished to create a flat coupling surface extending laterally and longitudinally across the first substrate (66, 70). The second substrate (91) is composed of a quartz block with a single v-groove holding a segment of single mode fiber (95). The radius of curvature of this v-groove is substantially smaller than that of the first substrate, such that the flat coupling surface of the second substrate (91) is shorter than that of the first substrate (66).

Abstract: A light source (10) coupled to a first fiber optic waveguide (14) which is coupled by a first directional coupler (22) and a second directional coupler (24) to a second waveguide (20). The first waveguide (14) has a phase modulator (60), a delay loop (62) and a polarization controller (68) therein to cause a differential delay time T on counterpropagating coherent light waves phase modulated at a frequency 1.sub.M. The first directional coupler (22) has one part connected to a photodetector (28) and the second directional coupler (24) has a probe (20D) coupled to the first fiber (14) and the second fiber (20). The probe directs light toward a surface (18) whereupon the counterpropagating waves are shifted in phase by an amount proportional to the amplitude of displacement of the surface 18.

Abstract: A semiconductor laser is frequency modulated and the output is put through an FM to IM converter. Intensity modulation is obtained at high frequency with the use of low switching current and minimal chirping oscillations.

Abstract: A load signal representing the load between a mold and an oscillating mechanism is separated into its static offset and dynamic components. The static offset signal is compared with a free-running static offset to obtain a substantially DC signal representing the DC component of mold friction. A DC voltage is generated corresponding to the RMS value of the dynamic load signal component, and a reference voltage corresponding to the RMS value of the dynamic signal component of a free-running load signal is subtracted in order to obtain a substantially DC signal representing the dynamic component of mold friction.

Abstract: An array (48, 49, 50, 51) of fiber optic couplers coupling an input (45) and an output (46) waveguide. The output waveguide (46) is routed among the couplers of the array such that either backward or forward coupling exists. With backward coupling, energy coupled into the output waveguide (46) in a coupler of the array is guided back to the preceding coupler for coupling back into the input waveguide (45).The backward coupling allows recirculations to occur between couplers to create poles and zeroes in the transfer function of the array which transfer function can be programmed or tailored somewhat to have specific characteristics. Further, the backward coupling allows the array to be used for matrix-vector multiplication.