Tunable-filter control method, tunable-filter control apparatus and optical communication system using the same
US5552919A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 10, 1995 |
| Grant date | Sep 3, 1996 |
| Priority date | — |
| Expiry date | Oct 10, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S5/0687
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A tunable-filter control method or apparatus tracks a central wavelength in a transmission spectrum of a tunable-filter to a wavelength of light to be received. The central wavelength in the transmission spectrum of the tunable-filter is periodically and minutely modulated. An error signal is generated for use in tracking the central wavelength to the wavelength of the light to be received, by using a tunable-filter output which exhibits the effect of the minute modulation of the central wavelength. A tracking condition, which corresponds to one of a draw-in state and a stable state, is monitored to control the modulation of the central wavelength based on a result of the monitoring, so that a modulation amplitude of the central wavelength in the minute modulation is increased at the time of the draw-in state of the tracking condition and is decreased at the time of the stable state of the tracking condition. A phase of an intensity modulation component of a transmission light transmitted through the tunable-filter may be compared with a phase of a modulation signal used for the minute modulation. In this case, the error signal is generated based on a result of the comparison.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.