Patent · US Expired

Optical signal control method and apparatus

US4988169A · kind A · utility

22Cited by
1References
20Claims
0Family size

Assignee

Inventor

Key dates

Filing dateMay 20, 1988
Grant dateJan 29, 1991
Priority date—
Expiry dateMay 20, 2008

Classification

  • Technology area (CPC Y)Emerging Cross-Sectional Technologies
  • CPC primaryY10S359/90
  • WIPO fieldOptics
  • WIPO sectorInstruments

Abstract

A method and apparatus for controlling the polarization of an optical signal has many applications, including in coherent systems, e.g. heterodyne detectors. Four birefringent elements (19, 21, 23, 25) in series are arranged to rotate the state of polarization (SOP) alternately about orthogonal axes on a Poincare sphere. A controller enables time varying initial and final polarization states (S, S') to be tracked. It also ensures that the birefringence limits of the elements are never reached by carrying out an adjustment procedure. A reduction by a full revolution (2.pi.) for one element (e.g. 19) can be achieved by varying the transformations of the other elements by not more than .pi..

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.