Abstract: An optical multi-channel data communication link transmits data from a transmitter to a remote receiver. The link includes a multimode laser diode source connected to the transmitter, a device for modulating the source with each channel of data to generate a modulated light wave, and a wavelength division multiplexing device at the transmitter. The wavelength division multiplexing device has paraxial optics for multiplexing the light waves to produce a multiplexed signal. Multimode fiber optic means are connected to the multiplexer and pass the multiplexed signal to the remote receiver. A wavelength division multiplexer has paraxial optics for demultiplexing the multiplexed signals at the receiver to produce demultiplexed light waves. Each of the demultiplexed light waves are converted for use by the receiver.

Abstract: A multiwavelength sensor for sensing light scattered from a scattering medium includes a light source, a uniform broadband reflection grating at the Littrow position, a fiber, and a detector. Light from the source is incident on the grating, which diffracts the light. The fiber has a first end into which the light diffracted from the grating is received and has a second end from which the light exits, the fiber being positioned so that the light is incident upon and scattered from the scattering medium. At least some of the light scattered from the medium is scattered back into the second end and out of the first end and incident upon the diffraction grating. Light out of the first end and diffracted from the grating is incident on the detector. The system is fully transparent so that light traveling toward the second end and light traveling back toward the first end are optically isolated and cross-talk is substantially nonexistent.

Abstract: A ladder architecture comprises an input optical fiber bus and an output optical fiber bus. A plurality of input optical couplers couple light between the input bus and a plurality of branching fibers. A plurality of output couplers couple light from the branching fibers to the output bus. The input bus and the branch fibers may be single mode optical fibers while the output bus a multimode optical fiber. The input couplers may be symmetrical, single mode devices, and the output couplers may be asymmetrical and single mode to multimode devices. The input bus may also be a multimode fiber, and the input couplers may also be multimode to single mode devices. The asymmetrical coupling reduces the amount of signal lost at fiber ends.

Abstract: A lattice includes a transmit bus formed of a single mode optical fiber and a return bus formed of a multimode optical fiber. An optical transmitter applies input signals to the transmit bus, and an optical receiver receives the signals guided by the return bus. The return fiber is looped around the couplers so that the signal output from each segment of the lattice passes through all the preceding segments before reaching the receiver. The optical couplers have asymmetric coupling efficiencies so that recirculating light is attenuated.

Abstract: A fibre optic lattice filter having a transfer function wherein the poles and zeros are adjustable independently of each other. The filter comprises a cascaded configuration of recursive and non-recursive fiber optic lattice filters. In one preferred embodiment, an all-pass fiber optic filter is formed by cascading all-pole and all-zero lattice filters, and by processing the resulting filtered output signal in a subtractive detection system. This detection system produces a signal which represents the difference between two signal outputs provided by the all-zero filter section, and which is adjustable in magnitude, thereby providing an overall filtering function which is capable of handling both positive and negative valued input signals.