Ridge waveguide sampled grating DBR lasers with 22-nm quasi-continuous tuning range

We demonstrate a ridge waveguide sampled-grating distributed-feedback laser with continuous wavelength coverage over a 22-nm tuning range, the largest ever reported for a ridge waveguide structure. The design is based on a 400-nm-thick 1.4-μm bandgap waveguide optimized for carrier injection tuning with offset quantum wells used to form the active region. The offset quantum wells enabled the device to be fabricated with only a single metal-organic chemical vapor deposition regrowth step. By tuning both mirror sections and the phase control section we were able to obtain 27 wavelength-division-multiplexed channels spaced at 100 GHz and precisely centered on the ITU grid with equal output power and greater than 40 dB of sidemode suppression ratio.