Simultaneous generation of eight wavelengths with about 20-nm spacing from a single semiconductor laser

Simultaneous generation of eight wavelengths spanning from 1367.1 to 1526.9 nm with about 20-nm channel spacing is achieved using a single semiconductor laser. The full-width at half-maximum of each mode is smaller than 0.3 nm. The sidemode suppression ratio is larger than 28 dB and the ratio of the signal to the background noise is larger than 30 dB. With careful adjustment of the loss for each mode, the power difference among those modes can be less than 3 dB. The performance of the eight-wavelength laser system can be further improved with the reduced loss of the external cavity.