Optical signal control method and apparatus
US4958918A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 3, 1989 |
| Grant date | Sep 25, 1990 |
| Priority date | — |
| Expiry date | Jan 3, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F2201/066
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Apparatus for processing one or more optical signals to produce a desired polarization transformation on a Poincare sphere has particular application in a receiver for a coherent communication system. One or more birefringent elements (11) receive a polarized optical signal from a local oscillator (12), and vary the state of polarization of the local optical signal in order to match it to a received optical signal from a remote source on a line (13). The transformed local signal is fed on a line (14) to a directional coupler (15) which compares the local and remote optical signals. A receiver (16) extracts data by interference between the two signals in the directional coupler (15), and feeds data out at a line (17). A level detector (18) detects the level of the output signal (17) and supplies a feed-back signal to a polarization controller (19), which controls the birefringent element or elements (11). The birefringent device (11) is adapted to provide a variable rotation on a Poincare sphere about an axis of rotation which itself may be varied in direction. The control means (19) varies the amount of rotation on the Poincare sphere produced by the birefringent device, and varies…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.