Three-section sampled-grating DBR lasers: modelling and measurements

The authors consider tunable semiconductor lasers with a tuning range of 29.4 nm suitable for a range of applications including wavelength-division multiplexing and wavelength routing. The structure considered has three-sections for gain, phase adjustment and grating feedback, respectively, and has a new and novel mode of operation. The grating is sampled periodically to give multiple peaks in the reflectivity spectrum; although this causes mode hops to occur, it allows a wider tuning range than a continuous grating. Time-domain modelling has been employed to analyse large signal dynamic behaviour of the lasers, and good agreement with observed behaviour is obtained. The complex structure of the devices makes this model slow, and static tuning characteristics identical to those from the time-domain model have been obtained more rapidly using transfer matrix calculations. Devices have shown 14.7 nm of tuning with complete coverage and 29.4 nm of tuning with partial coverage with at least 30 dB side-mode suppression ratio (SMSR)