High-power DBR lasers at elevated operation temperature

Various commercial fieldable sensing applications require compact, robust, and stable single-frequency laser sources. Distributed Bragg reflector (DBR) lasers enable single-frequency operation without an external cavity and alignmentsensitive components. This makes them the solution of choice for compact and robust sensors. At elevated temperatures, effects such as carrier leakage and non-radiative recombination lower the output power, efficiency, and overall performance of diode lasers. To counter the self-heating of diode lasers, they are usually cooled with a Peltier element. To reduce the SWaP-C (size, weight, power, and cost), it is desirable to operate the laser at an elevated temperature and use resistive heating to maintain a stable operating point. Various positioning, navigation, and timing-related applications utilize lasers stabilized to alkaline vapor cells. To increase the vapor pressure, the gas cells must be heated, and the more they are heated, the smaller their volume can be. If the laser can be operated at similar temperatures, it can be integrated close to the gas reference, avoiding temperature gradients and making the overall system more compact. To achieve efficient elevated temperature operation, various design considerations need to be taken into account. The band structure of the epitaxial material must be optimized for good carrier confinement. Additionally, the gain peak of the epitaxial material and the reflectivity peak of the Bragg reflector shift at different rates when the temperature changes. Therefore, to achieve optimal performance, they must be designed to coincide at the operating temperature. In this paper, we demonstrate the performance of DBR lasers at various temperatures, focusing on high operating temperatures. We focus on the rubidium D1 line transition at 794.8 nm.