US 7,068,949 B2 · Multi-wavelength locking method and apparatus for wavelength division multiplexing (WDM) optical communication system

Abstract

Disclosed is a multi-wavelength locking method for a wavelength division multiplexing (WDM) optical communication network, and in particular, a multi-wavelength locking method and apparatus for a WDM optical communication system that can lock wavelengths of optical signals by producing pilot tones by applying a sine-wave current to a plurality of transmission lasers having different wavelengths, passing the optical signal through a Fabry-Perot etalon filter, and then Fourier-transforming the filtered optical signal. The multi-wavelength locking method includes frequency-modulating an optical signal by applying a small and specified sine-wave current to a bias current for driving WDM lasers, detecting pilot tones produced after filtering the optical signal through a filtering section and converting the detected signal into a digital signal by performing a sampling of the detected signal, detecting a magnitude and phase of the pilot tones by performing a fast Fourier transform, providing Fourier-transformed data as a first derivative signal of the filtering section, and locking an operation wavelength of WDM channels by controlling the temperature or current if resonance frequencies of the filtering section coincide with respective standard frequency.

Claims16

Dependent claims

A multi-wavelength locking apparatus for a wavelength division multiplexing (WDM) optical communication system, comprising:

modulation means for modulating output wavelengths of a plurality of transmission lasers having different wavelengths;
optical distribution means for dividing an optical signal into two parts to lock wavelengths of the wavelength-division-multiplexed optical signal simultaneously;
first optical detection means for detecting one of the two divided parts of the optical signal;
optical filtering means for filtering the wavelength-division-multiplexed optical signal in an optical frequency range;
second optical detection means for detecting the other of the two divided parts of the optical signal after passing through the optical filtering means to lock the wavelengths of the wavelength-division-multiplexed optical signal into respective reference frequencies;
operation means connected to the first and second optical detection means for detecting a first derivative of the optical filtering means by performing an operation with respect to the two divided parts of the detected optical signal, one of said parts being filtered by said optical filtering means and the other of said parts being unfiltered by said optical filtering means;
and
output means for producing a specified output for controlling the transmission lasers in accordance with the detected first derivative.

5 more elements

Dependencies are inferred from the claim text.

Multi-wavelength locking method and apparatus for wavelength division multiplexing (WDM) optical communication system

Life of this patent

Multi-wavelength locking method and apparatus for wavelength division multiplexing (WDM) optical communication system

Life of this patent

Abstract

Claims16