Modelling of phase-grating based wideband tuneable lasers with simplified quasi-digital wavelength selection

A transfer matrix based model is discussed which was used to simulate a novel wideband tuneable laser design. This model can simulate the predicted behaviour of an arbitrary, multi-section distributed Bragg reflector (DBR) laser and can successfully predict tuning behaviour, threshold current, output power and static side-mode suppression ratio. The particular DBR laser, the digital super-mode DBR (DS-DBR), tunes by means of a highly uniform comb of narrow reflection peaks coupled with a multi-grating structure that can be used to digitally select a sub-band of the total tuning range. By selecting sub-bands in turn, the whole tuning range of the device can be accessed. Results of the model are compared with experimental results for this device which show a tuning range of around 50 nm, together with output powers in the range 8-9 dBm and a side-mode suppression ratio of better than 50 dB over 80 WDM channels at 50 GHz spacing. These results are for a device packaged in a standard 26-pin butterfly module.