Patent ID: 7068949

Claim:
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.