Polarization matching mixer
US4723315A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 24, 1986 |
| Grant date | Feb 2, 1988 |
| Priority date | — |
| Expiry date | Jun 24, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B10/64
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A method of mixing light from a signal source with light from a local oscillator for heterodyne or homodyne detection using differential detection techniques is described. In the method and apparatus of the invention, incoming light is matched to the polarization of the local oscillator no matter what the polarization of the incoming light is. A sequence of three polarization beamsplitters is utilized to achieve this match. The local oscillator signal and the incoming signal are incident on separate faces of a first polarization beamsplitter. Each is divided into two beams by that beamsplitter and paired with the orthogonally polarized component of the other, each signal/local oscillator pair exiting from one exit face of the first polarization beamsplitter. The second polarization beamsplitter resolves one of these pairs into sum and difference pairs of matched polarization which interfere and are detected by square law detectors, forming currents which are subtracted in a differential amplifier. The third polarization beamsplitter repeats this process with the other pair of beams from the first polarization beamsplitter. The result is two net output currents which between them co…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.