Control of an optical modulator for desired biasing of data and pulse modulators
US7394992B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 11, 2003 |
| Grant date | Jul 1, 2008 |
| Priority date | — |
| Expiry date | Feb 22, 2025 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B10/516
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
In an optical transmitter, continuous wave light from a laser passes through a data modulator (DM) for non-return-to-zero (NRZ) encoding of a data stream and through a pulse modulator to add return-to-zero encoding to the modulated optical signal. A modulator controller monitors the output optical signal power, optimizes the bias setting for the DM and the PM, and optimizes the phase relationship between the pulse and data components of the modulated optical signal. For each optimization, a low amplitude and low frequency dither signal is injected at appropriate points in the modulator. A single photo detector and electrical receiver are used in a multiplexed fashion to monitor the optical output signal and derive separate feedback signals. Remaining control circuitry forces a null in a respective residual dither component in the optical output signal to maintain the desired bias level or phase alignment.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.