Device noise measurement system
US6320179A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 15, 1999 |
| Grant date | Nov 20, 2001 |
| Priority date | — |
| Expiry date | Apr 15, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S3/0014
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A system and method for determining noise power levels across a range of frequencies of the optical signal output from a device operating at a specified optical power and drive current and, in particular, for determining relative intensity noise values (RIN). The system may comprise a reference laser for generating an optical reference signal and a photodetector for converting the optical signal output from the reference laser and the device under test into equivalent electrical signals. The system also comprises means for measuring ac and dc components of the electrical signals output from the photodetector. The system may be used to measure RIN levels to an accuracy of less than 1 dB. Such measurements are of particular importance in the field of fiber optic telecommunications. The reference laser is shot noise limited in the frequency range of interest, typically between 20 MHz and 20 GHz, and has a narrow linewidth, typically less than 5 kHz. A shot noise limited reference laser signal may be achieved by means of optically attenuating a higher power reference laser signal to the required lower optical power. The incorporation of a reference laser enables a simple calibration pr…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.