Canadian Patents & Dev. Limited

Her Majesty the Queen in Right of Canada, As Represented by the Minister

Canadian Patents and Development Limited/societe Canadienne Des Brevets

R Ian MacDonald

Elmer H Hara

Brian S Kawasaki

Robert H Hum

R W Jenkins

Robert S Hum

D K Lam

An optoelectronic switching matrix which can be configured to form a variety of signal processing elements, such as a digital switched filter, a digital word generator, a programmable bandpass filter, programmable delay, etc. Optical or electronic delay apparatus is connected between output and input ports of the matrix, and can be switched to provide delays or resonant loops. A versatile signal translation element is thus realized.

Reflex optoelectronic switching matrix

Logic circuits employ photoresponsive GaAs field effect transistors to directly drive GaAs laser diodes to provide optical output signals in response to optical input signals. Since the only electrical inputs are DC bias voltages, each such circuit can be readily decoupled, such as for use in electrically noisy environments. The optical output represents a predetermined logic condition in response to a predetermined operating current applied to the laser diode as a result of the operation of the photoresponsive device. Two photoresponsive devices may be used to apply two different operating current magnitudes to the laser diode to produce two different optical output signals.

Optoelectronic logic

The optoelectronic switch includes a photosensitive GaAs FET onto which an optical signal may be directed. The optical signal is derived from an RF modulated light source. A voltage circuit is connected to the FET to switch the FET 'on' or 'off' by placing a positive or zero voltage respectively on the drain. An isolation of over 70 dB is obtained in this FET switch.

Broadband high speed optoelectronic semiconductor switch

The optoelectronic cross-point switch suitable for a broadband switching array includes a photodiode which converts an optical signal impinging upon it to an electronic signal and a biasing circuit for selectively reverse biasing the photodiode to render the photodiode responsive to the optical signal or forward biasing the photodiode to render the photodiode substantially non-responsive to an optical signal. The biasing circuit consists of positive and negative voltage sources and a controllable switch to connect the sources to the photodiode. A load circuit which is connected to the photodiode for developing the output signal may consist of a single resistor, a pair of series resistors, an operational amplifier with feedback or an rf transformer. The load circuit can also include an rf switching diode connected to the photodiode to improve isolation and to reduce the electrical power required to forward bias the photodiode.

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Ottawa, Canada

R Ian MacDonald