Abstract: A direct optical connector (DOC) comprised of first and second members, each including a plurality of light emitting and light detecting locations, operative in combination with energy transfer media to form direct optical connections between the light emitting locations and the light detecting locations, wherein said first and second members are adapted for reclosable connection to each other whereupon the light emitting locations on one member are aligned with the light detecting locations on the other member. The first and second members of the preferred DOC are modular. Alternative forms of energy transfer media are used in various embodiments of the invention including lenslet arrays, imaging fiber plates (IFPs), and energy transfer fiber plates (ETFPs). These media have differing alignment criteria, differing degrees of immunity from crosstalk, differing degrees of transfer efficiency, different manufacturing costs, etc.

Abstract: A semiconductor photodetector is formed of interdigitated, metal-semiconductor-metal electrodes disposed on a surface of semi-insulating semiconductor material, gallium arsenide. Radiation such as infra-red or visible light is converted to an electric current flowing between the electrodes upon application of a bias voltage between the electrodes. A Schottky barrier at the junction of each electrode surface and the semiconductor surface limits current flow to that produced by photons. Tunneling of charge carriers of the current under the Schottky barrier, which tunneling results from the entrapment of charge carriers on the semiconductor surface, is inhibited by the production of a heterojunction surface layer upon the foregoing surface between the electrodes to repulse the charge carriers and prevent their entrapment at the surface. The heterojunction layer may be doped to enhance the repulsion of charge carriers.

Abstract: A semiconductor photodetector is formed of interdigitated, metal-semiconductor-metal electrodes disposed on a surface of semi-insulating semiconductor material, gallium arsenide. Radiation such as infra-red or visible light is converted to an electric current flowing between the electrodes upon application of a bias voltage between the electrodes. A Schottky barrier at the junction of each electrode surface and the semiconductor surface limits current flow to that produced by photons of sufficient frequency, or energy, to overcome the Schottky barrier. Tunneling of charge carriers of the current under the Schottky barrier, which tunneling results from the entrapment of charge carriers on the semiconductor surface, is inhibited by the production of a doped surface layer upon the foregoing surface between the electrodes to repulse the charge carriers and prevent their entrapment at the surface.

Abstract: A multi-stage current mode differential amplifier is disclosed in which each cascaded stage includes a pair of input transistors which have their bases connected to a common voltage source and a pair of control transistors which have their emitters connected to a common current source. A diode-like device is inserted between the collector of a control transistor in one stage and the emitter of an input transistor of the succeeding stage which increases the input impedance seen by the control transistor, thereby permitting an increase in amplification for that stage. In both embodiments, the current signal is amplified at a higher rate than the rate of increase of the bias currents supplied to the emitters of the control transistors in each stage.