Northern Telecom Limited

Jds Fitel Inc.

Fitel Photomatrix

Yves Tremblay

David John Nicholson

John D Ralston

Roman Maciejko

F David King

Romain Maciejko

Ian S Few

A method and system is provided wherein an n channel system is equipped with n uncooled inexpensive lasers not requiring optical isolators provide optical signals to the n broad channels. Advantageously, the system can be installed at a reasonable cost to the first n users and be upgraded in number of channels and cost as the need for the system to evolve and grow arises. Each of the n uncooled lasers are tuned such that at ambient temperature, their central wavelength is below their respective channel mid wavelength.

Optical communication system

In optical communications systems crosstalk can result in what is termed silent failure. In silent failure, a faulty transmitter appears to function correctly because a receiver in communication therewith is receiving a signal induced by crosstalk. The invention overcomes this problem by tapping the received signal and monitoring it external to the receiver in order to ensure adequate signal levels for a received signal. A microcontroller disables the failed circuit and in an embodiment switches the communication functions to a stand-by circuit.

Circuit and method of testing for silent faults in a bi-directional

A binary data signal is regenerated with respect to three threshold levels, one of which is derived from and lies between the other two so that it is an optimum level for producing a regenerated output signal. Two control loops are used to produce the other two threshold levels to produce regenerated signals with predetermined error rates, the errors occurring on the two control loops for the two respective states of the binary data signal, whereby the optimum threshold level is maintained regardless of the nature of signal degradation. The arrangement provides rapid performance monitoring which can also be used to adjust other parameters, such as detector bias, equalizer tuning, and clock phase, for optimum performance in an active and ongoing manner.

Binary data regenerator with adaptive threshold level

A fiber optic star coupler particularly for use in providing optical interconnects between circuit boards has a light mixer into which input and output fibers are inserted. The mixer has rectangular cross-section passage, an interior surface of which is highly reflecting. The mixer is long enough to promote a degree of internal reflection of light from any one of the input fibers sufficient that the corresponding light intensity reaching the output fibers is substantially uniform. In an optical interconnect arrangement, interconnection between circuit boards in a rack or cabinet is achieved by mounting light emitting and light receiving units on each board and leading fibers to which the units are fixed to the fiber optic star coupler so that light from the emitter units enters one end of the light mixer and fibers leading to the receiver units enter the opposed end of the light mixer. The fiber optic star coupler is substantially cheaper and more easily manufactured than known fiber optic star couplers using a polished glass slab as a light mixer.

Fiber optic star coupler

A fiber optic access node has input and output fibers terminating at a housing. A module is retractably insertable into the housing to automatically lock into a position in which an output zone of the module aligns with the output fiber and input zone of the module aligns with the input fiber. The input and output zones may be those of fiber optic passive elements such as a bypass fiber, a fiber tap, a fiber extension loop or a wavelength division multiplexed device, or may be those of an active element such as a repeater incorporating a light emitter, a light detector and a control circuit. The fiber optic element may be encapsulated within a plastics block or can be clamped between two plates. The combination of module and housing allows rapid and easy substitution of fiber optic functions within a fiber network.

Growing community of inventors

Nepean, Canada

Yves Tremblay