Browse Prior Art Database

Multimode Bidirectional Optical Communication Link

IP.com Disclosure Number: IPCOM000088019D
Original Publication Date: 1977-Apr-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Callahan, RW: AUTHOR

Abstract

A method is described for transmitting data and clock pulses through an optical fiber or fibers bidirectionally in two different modes. One mode is an interlocked mode where the send side waits for a received clock signal to continue. In this mode, the receiver governs the transmission rate of the send side. The other mode allows simultaneous transmission in both directions, and transmission in either direction may be asynchronous and at different rates.

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Multimode Bidirectional Optical Communication Link

A method is described for transmitting data and clock pulses through an optical fiber or fibers bidirectionally in two different modes. One mode is an interlocked mode where the send side waits for a received clock signal to continue. In this mode, the receiver governs the transmission rate of the send side. The other mode allows simultaneous transmission in both directions, and transmission in either direction may be asynchronous and at different rates.

Fig. 1 is a diagram of a point-to-point optical communication link. The link is comprised of an optical fiber (or fibers) 10 and a pair of send/receive stations A and B. Station A includes light-emitting diodes 11 and 12, photodetector diodes 13 and 14, a prism 15 and an interfacing lens 16. Station B includes light- emitting diodes 21 and 22, photodetector diodes 23 and 24, a prism 25 and an interfacing lens 26. Data is transmitted through the optical fiber 10 by short pulses of light from the light-emitting diodes and detected at the receiving end by means of the photodetector diodes. Different wavelengths of light are chosen so that the prisms will collimate the different wavelengths into a narrow beam at one end and disperse the beam into individual bands at the other end. Silicate flint glass, for example, exhibits a greater change in its refractive index for different wavelengths of light than most other materials. The selection of different wavelengths also allows transmission in opposite directions without total destructive interference. Fig. 1 shows station A sending yellow clocking/gating pulses with red data, while recei...