Thermal strain magnification for wide wavelength tunability of 1.55 /spl mu/m lasers

The range over which the wavelength of an InP-based laser's wavelength may be temperature-tuned is limited by the relatively poor high-temperature performance of these lasers. We have increased the temperature-tuning rate, and thus the practical tuning range, by using stress from differential thermal expansion to increase the rate at which the refractive index drifts with temperature. We have further enhanced this effect by using a strain-concentrating trench, etched below the laser waveguide. We have obtained a 50% increase in the tuning rate, without any degradation in the LI characteristic, and have observed as high as an 86% increase.