Abstract

The potential of widely tunable lasers for deployment in future dense WDM networks is widely acknowledged. A variety of device types have been proposed as reviewed recently in.¹ Amongst these, InP based four section DBR lasers can achieve >60 nm tuning, easily covering one of the Er-doped fibre amplifier windows, and also have the potential for high speed wavelength switching.² The change in refractive index that can be achieved by current injection into a grating section is limited to about 1–2% or 10 nm in wavelength. One way to enhance the tuning range is to use a comb reflector with many reflection peaks and then find a means of peak selection. In the SG-DBR laser this selection is achieved by vernier tuning between two different grating combs one at the front and one at the rear of the device. In the GCSR selection is via an internal transmission filter. Vernier tuned devices require complex current control algorithms in three or four dimensional space. In this paper, a new multi-section DBR laser is presented with modeling and initial experimental results. As discussed below this laser can be controlled in a quasi-digital manner by just one grating current and one phase adjustment current, giving significant advantages for setup and test and implying scalability.

© 2002 Optical Society of America