High-power single-frequency semiconductor lasers

Abstract

We have developed a single-frequency tapered laser emitting at a wavelength of 1.55 pm. The ridge waveguide section enables only one lateral mode, while the DBR structure provides single ffequency operation. This tapered laser has 20 dl3 side-mode suppression at continuous wave (CW) power levels up to 0.6 W. 80 'YO of the power from this device remains in the central lobe of the far-field at a power level of 0.5 W. A Gaussian contact over the tapered section matches the current distribution to the lateral optical profile reducing self-focusing and beam instability effects. We are also developing both distributed feedback (DFB) and distributed Bragg reflector (DBR) angled-stripe semiconductor laser designs for high power. To obtain power levels approaching 10 W, we are using a lenslike waveguide that causes divergence along the lateral direction along with a second order grating to provide outcoupling along the surface of the device.