Wide-wavelength tuning of sampled grating tunable twin-guide laser diodes

Abstract

Tunable laser diodes with a tuning range of several tens of nanometers are generally being acknowledged as key components for future generation optical networks. However, all presently available devices suffer from several serious drawbacks. The most well-known issue is the time-consuming calibration procedure that has to be carried out for every single device. Recently the so-called sampled or superstructure grating tunable twin-guide or (S)SG-TTG laser diode has been suggested to overcome some of the prevailing problems. In this paper we will present tuning characteristics of first devices and discuss the influence of facet reflections on the tuning behaviour. The widely tunable twin-guide laser diodes operate around 1.55 µm and have a continuous tuning range of ~ 2 nm. However, by utilizing Vernier-effect tuning, the overall quasi-continuous tuning range is extended to 28 nm. Within this tuning range, five supermodes can be continuously tuned without the occurrence of any mode hops. The side-mode suppression ratio is kept between 25 and 37 dB.