Heterodyne based optical spectrum analysis with controlled optical attenuation
US7012697B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 24, 2002 |
| Grant date | Mar 14, 2006 |
| Priority date | — |
| Expiry date | Jan 28, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01J2001/0276
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical heterodyne detection system includes an attenuator for attenuating an input signal before the input signal is combined with a local oscillator signal. An optimal attenuation level for the input signal, which improves the signal to noise ratio of the heterodyne beat signal, is determined by obtaining a base measurement of an output signal in response to the local oscillator signal and in the absence of the input signal, obtaining sample measurements of the output signal in response to the input signal as a function of different attenuation levels, and determining the optimal attenuation level as a function of the base measurement and the sample measurements. A minimum attenuation level for the input signal, which protects receiver photodetectors from being saturated or damaged, is determined by setting an initial attenuation level and gradually reducing the attenuation level until the voltage limit of the photodetectors is reached.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.