Optical multiplexer
US5363221A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 16, 1992 |
| Grant date | Nov 8, 1994 |
| Priority date | — |
| Expiry date | Oct 16, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B10/11
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Light from a laser (10) is divided by a beam splitter (12) to provide signal (15) and reference (14) channels. The signal channel light is expanded (11) to illuminate an acousto-optic (AO) device (13). This leads to a spatial distribution of Doppler shifted frequencies. This spatial distribution then illuminates a spatial light modulator (SLM) (19) such that a number of parallel and discrete optical channels (112) emerge. In a local area network (LAN) the optical signal channels are coupled into a single mode optical fibre (22) and then heterodont to the reference laser light from a further optical fibre (23) in an optical coupler (25). In a receiver the modulated light is detected (32) and the detected signal connected to the transducer of an AO device (35). The AO device (35) is illuminated by a receiver laser light (36) and the emerging modulated light is incident on a focal plane detector array (39) where each detector (310) then receives light corresponding to each of the transmitted channels (311). A secure free space communications system is possible by separate transmission of a delayed (43) unmodulated reference signal. The receiver is then arranged to include an identical…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.