Patent ID: 7139450

Claim:
A laser transmitter device for dense wavelength-division multiplexing optical communication, comprising: a laser light source, whose oscillation wavelength is tunable; a first optical element having a first optical characteristic with wavelength dependency, whose light transmissivity or reflectivity shows a monotone increase or monotone decrease within a wavelength range over a plurality of channels in the optical communication; a second optical element and having a second optical characteristic with wavelength dependency, whose transmissivity or reflectivity changes in a cycle corresponding to intervals of the channels or two times the intervals; a first detection element configured to detect an intensity of light emitted from the laser light source and coming via the first optical element, and generate a first electric signal reflecting the first optical characteristic; a second detection element configured to detect an intensity of light emitted from the laser light source and coming via the second optical element, and generate a second electric signal reflecting the second optical characteristic; and a controller configured to tune the oscillation wavelength of the laser light source to a wavelength of a predetermined channel selected from the channels, wherein the first detection element is disposed to detect an intensity of light emitted from the laser light source and coming via the first optical element and not via the second optical element, and the second detection element is disposed to detect an intensity of light emitted from the laser light source and coming via the first and second optical elements, the controller receives the first and second electric signals, and performs a first stage adjustment of adjusting the oscillation wavelength of the laser light source into a wavelength capture range of the predetermined channel, based on a signal reflecting the first optical characteristic, and then a second stage adjustment of fine-tuning the oscillation wavelength of the laser light source to the wavelength of the predetermined channel, based on a signal reflecting the second optical characteristic, and the controller performs the first stage adjustment based on the first electric signal, and the second stage adjustment based on an output obtained by subjecting the second electric signal to a division process by the first electric signal.