Optical detector for detecting optical signal beams, method to detect optical signals, and use of an optical detector to detect optical signals

摘要

An Optical detector for detecting an optical signal beam modulated in a way that it comprises an in-phase and/or a quadrature component, comprises a polarisation beam splitter (315a; 602) arranged to split the optical signal beam (301 a; 601; 701 a; 801) into two polarised optical signal beams (313a; 313b), a non-polarisation beam splitter arranged to further split each of the two polarised optical signal beams into two split polarised optical signal beams, at least one birefringent element (309; 310; 311; 401; 402; 501; 502; 503; 603a; 603b) providing a phase shift, the birefringent element being arranged in a path of at least one polarised optical signal beam (313a; 313b) and/or in a path of at least one split polarised optical signal beam so that an in-phase and quadrature phase offset between two split polarised optical signal beams originating from the same polarised optical signal beam (313a; 313b) is formed in output signal beams; and at least two detection means (302a, 302b, 303a, 303b, 304a, 304b, 305a, 305b, 702a, 702b, 703a, 703b; 802a, 802b) arranged to receive at least one output signal beam that comprises a in-phase and/or quadrature component of the optical signal beam (301 a; 601; 701 a; 801).