An optical detector comprises an array of PIN diodes each of which shows no photovoltaic output at zero bias but which can produce a photovoltaic output when correctly biased. A single amplifier is coupled to the array for amplifying produced photovoltaic voltages. When an optical signal incident on a particular PIN diode is required to be detected, that PIN diode is selectively and correctly biased by closure of an associated switch and the PIN diode output is amplified by the amplifier.

An optical transmitter/receiver pair has an integrated CMOS circuit that provides a current flow to a pre-biased solid state light emitting device (LED) in response to the presence or absence of a digital input signal. The current flow is augmented at the rising and falling edges of the input signal to enhance turn-on and turn-off speed of the LED. The LED is optically coupled to a photodiode that produces a current flow in response to illumination. The photodiode is shielded from spurious electronic noise by a transparent shield and the output of the photodiode is amplified to produce an output voltage, which is connected to a capacitively delayed voltage divider. The voltage divider generates a time delayed threshold voltage connectable along with the output voltage to the inputs of a comparator.

A light conductor has two sealed embedding elements molded to its ends, respectively containing a light emitter and a light receiver. The light emitter is connected to a likewise embedded Wiegand probe, the light receiver is connected to a likewise embedded amplifier and a pulse shaper. These signal transmission lines are used for data acquisition, the respective Wiegand probes are disposed to be responsive to measured conditions represented by variable magnetic fields. The transmission system is moisture-proof and insensitive to interfering electromagnetic radiation.

An rf multiplexer includes a plurality of rf switch assemblies for switching a selected rf signal to an output in response to an optical control signal. Each rf switch assembly includes a switch circuit mounted in a conductive enclosure. The optical control signal from a control circuit is coupled by an optical fiber into the enclosure to an optical receiver which energizes a diode rf switch. Spurious conduction of rf signals along switch control lines is thereby eliminated without using filters. The multiplexer is particularly useful in a direct frequency synthesizer requiring high speed switching.

A bulk semiconductor laser which uses optically triggered avalanche conduction to initiate the lasing action in the bulk. A semiconductor block has electrodes coupled on opposing sides and a high voltage is applied across the electrodes which is less than the voltage required for avalanche breakdown. The block is irradiated with light which produces charge carriers in the block to initiate avalanche conduction, which results in a large number of charge carriers. The charge carriers recombine to generate a second amount of electromagnetic radiation. This radiation is reflected back into the block on two opposing sides, thus resulting in a laser emission.