Bidirectional free-space optical bus for electronics systems
AssigneeInternational Business Machines Corporation
InventorsTimothy R. Block, Tong Lu
Life of this patent
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Abstract
An electronics system communicates among its subsystems by a free-space optical bus. The bus transmits signals bidirectionally along a single linear axis as polarized beams of light. Each subsystem has a bus interface unit for generating outgoing beams along both axial directions, and for receiving incoming beams from both axial directions. The interface units use laser generators, photodetectors, and amplitude beam splitters.
Claims22
A subsystem for an electronics system having multiple subsystems mounted in a frame so as to define a single axis passing through said subsystems, said one subsystem comprising:
- a support adapted for mounting on said frame;
- function circuits carried by said support, and adapted to produce a first electrical signal and to receive a second electrical signal;
- optical generating means for converting said first electrical signal into a first optical beam having a predetermined polarization;
- an amplitude beam splitter mounted on said support so as to intersect said axis, and optically coupled to said generator for transmitting said first optical beam in two opposite directions along said axis in said predetermined polarization, and for receiving a second optical beam having said predetermined polarization from either of said two opposite directions along said same axis;
- optical detecting means coupled to said amplitude beam splitter for converting said second optical beam into said second electrical signal.
An optical interface unit for coupling electrical signals to an optical bus, comprising:
- optical generator for converting a first electrical signal into an outgoing beam having a first linear polarization mode;
- a polarizing beam splitter for passing said first outgoing beam and for deflecting an incoming optical beam having a linear polarization in a different mode from that of said outgoing beam;
- a polarization converter intercepting said first outgoing beam so as to convert its linear polarization to circular polarization, and further intercepting said second incoming beam so as to convert its circular polarization to linear polarization in said different mode;
- an amplitude beam splitter positioned so as to intercept said outgoing circularly polarized beam for transmitting said beam in two opposite directions along a single optical axis, and for receiving said incoming beam from both of said two opposite directions along said same axis and passing said incoming beam both along said axis in the other of said directions and to said polarization converter;
- an optical detector positioned so as to receive said incoming deflected beam from said polarizing beam splitter, for converting said incoming optical beam into said second electrical signal.
A method for coupling first and second electrical signals to an optical bus having a single linear axis, comprising:
- converting said first electrical signal to an outgoing optical beam, said beam being polarized in a first linear mode;
- transforming said outgoing beam to circular polarization;
- splitting said outgoing beam into two outgoing beams traveling in two opposite directions along said linear axis;
- splitting an incoming beam having circular polarization and traveling along said same linear axis in either one of two mutually opposite directions into two incoming beams, one traveling further along said axis in said either one direction and the other deflected from said axis;
- transforming said deflected incoming beam to linear polarization in a second mode different from said first mode;
- converting said transformed deflected beam into said second electrical signal.
Dependencies are inferred from the claim text.