Abstract: The present applicant has discovered that one can make a surface emitting laser with enhanced operating characteristics by etching away the outer reflector stack peripheral to the intended active area and protecting the reflector stack mesa remaining over the active area by in situ metalization in high vacuum. The active area can be isolated, as by ion implantation, providing an electrical path through the active region free of the outer reflector stack. The result is a surface emitting laser having reduced series resistance. The device lases at lower voltage and provides an enhanced intensity of optical output as compared with conventional planar devices.

Abstract: The present applicants have discovered that one can make a surface emitting laser with enhanced optical confinement and improved heat sinking characteristics by etching away portions of the growth layers peripheral to the intended laser cavity and regrowing peripheral regions of material having a lower index of refraction than the active region. Using low damage etching and either in situ regrowth or hydrogen plasma cleaning followed by regrowth, a surface emitting laser having enhanced optical isolation and heat sinking characteristics can be made.

Abstract: Hydrogen Plasma surface passivation of III-V Semiconductors is critically dependent on exposure time and pressure because of competition between plasma passivation and damage. Proper control of pressure according to the invention yields reproducible and stable passivation. Improved passivation is obtained using high pressure hydrogen plasmas, i.e. above 1 Torr.

Abstract: The present applicants have discovered that a layer predominantly comprising tungsten can be formed into precise patterns having substantially vertical walls by using titanium as a mask and plasma etching in a fluorine-containing plasma such as CF.sub.4 or SF.sub.6. The success of the process is believed attributable to the occurrence of an etch stop reaction on the sidewalls of the tungsten. The products of the reaction inhibit horizontal etching. After the tungsten is etched, the titanium mask can be selectively removed, as by etching in dilute HF. Each step in the process can be effected without subjecting the workpiece to voltage magnitudes in excess of 200 volts or temperatures outside the range between room temperature and 200.degree. C.

Abstract: Applicants have discovered photo-induced second harmonic generation in rare earth doped glass bodies free of germanium. Moreover, applicants have discovered that multivalent rate-earth doped glass bodies can be made with conversion efficiency of second harmonic generation in excess of 10.sup.-3 % per watt, exceeding the reproducible efficiency of germanium doped glass. In accordance with the invention, a light source of a desired frequency comprises a body of glass doped with a multivalent rare earth element, an optical input source of light at one-half the desired frequency, and utilization means for receiving light passing through said body and utilizing light at the desired frequency.

Abstract: An integrated photodiode is formed by providing a silicon substrate with a deep recessed tub in excess of about 20 microns, forming an isolated p-n junction on the peripheral tub surfaces, and selectively epitaxially filling the tub with intrinsic silicon. A desired monolithic integrated circuit is fabricated outside the tub periphery using conventional VLSI techniques. A photodiode electrode structure within the tub periphery can be fabricated at the same time as other monolithic circuit components are formed.

Abstract: The present invention is a semiconductor laser having an integral photodiode and/or modulator. The integrated structure comprises a quantum well active region sandwiched between a pair of distributed Bragg reflector stacks for emitting laser light transverse to the planes of growth. An intrinsic layer and a doped semiconductor layer are disposed on one of the reflector stacks for forming, in combination with the outer layer of the stack, a photodiode in the path of emitted light. The diode can be used either to monitor the laser power or to modulate the laser output. The device is particularly suited for fabrication and testing in large arrays and, in addition, has the advantages of a circular, low divergence optical output, inherently single mode operation, and a high two-dimensional packing density.

Abstract: The present applicant has discovered that gold can be patterned by masking and reactively ion etching in a CF.sub.4 /O.sub.2 plasma. In accordance with the invention, a layer of gold is patterned by the steps of a) forming a layer of gold on a substrate, b) masking the gold layer to selectively expose a pattern to be etched, c) exposing the masked layer to a CF.sub.4 /O.sub.2 plasma. In preferred practice, the substrate comprises a gallium arsenide substrate having an interface layer comprising titanium to promote adhesion of the gold layer, and the gold layer is formed by sputtering onto the interface layer. The gold layer is masked by photoresist, and the masked layer is exposed to a CF.sub.4 /O.sub.2 plasma with the molar percent of O.sub.2 in excess of about 8%. Advantageously, the exposed intermediate layer can be plasma etched away.

Abstract: The formation of latent images in photoresist can be monitored during exposure without spurious images by directing a pulsed beam of monochromatic light onto a region of the layer being exposed and selectively detecting the diffracted light. Peak formation in the normalized diffracted intensity versus time curve indicates optimal exposure of the resist.

Abstract: The present invention is predicted upon the discovery by applicants that is scattered light from an etched workpiece is measured over many orders of diffraction, important characteristics of the etched workpiece can be correlated with the principal component content of the intensity characteristic. In accordance with the present invention, an etched workpiece is inspected by 1) exposing the workpiece to a beam of coherent light, 2) measuring the intensity of the light scattered from the workpiece over a range of spatial frequencies corresponding to a plurality of diffraction orders, 3) determining the principal component content of the tested workpiece intensity envelope, and 4) accepting or rejecting the workpiece in accordance with whether or not the principal component content satisfies predetermined criteria. In preferred embodiments the principal components are determined in relation to a plurality of reference measurements by singular value decomposition.

Abstract: Systems for transmitting and/or receiving electromagnetic signal radiation are disclosed. The inventive systems are distinguished from previous such systems in that each includes at least one resonant cavity comprising a housing containing a body, e.g., a cylindrical or helical body, of relatively high T.sub.c superconducting material. Significantly, this body is fabricated using a new, unconventional procedure. As a result, the body exhibits substantially lower surface resistances than either previous such bodies of relatively high T.sub.c superconducting material, fabricated using conventional procedures, or bodies of copper, at 77 Kelvins and at frequencies ranging from about 10 MHz to about 2000 MHz. Moreover, as a consequence, the resonant cavity containing the unconventionally fabricated body exhibits much higher quality factors, Q, at the above temperature and frequencies, than previous such cavities containing either conventionally fabricated bodies of relatively high T.sub.

Abstract: A light source, such as an LED, is provided with a multifaceted reflector to facilitate coupling of emitted light into an optical waveguide such as an optical fiber. In a preferred embodiment, a conventional LED fabricated on one side of a transparent substrate is provided with a series of integral concentric reflecting rings on the opposite side of the substrate. The rings reflect light diverging from the LED toward the central axis of an optical fiber light.