Published in: OPTO SPIE 2024
Authors: Mika Mähönen, Riina Ulkuniemi, Luukas Kuusela, Timo Aho, Andreas Schramm, Soile Talmila, Pekko Sipilä, Petteri Uusimaa
Laser systems with ultra-stable and narrow linewidth operation are a crucial part for many quantum computing and quantum sensing technologies, such as trapped ion and neutral ion approaches. The particular interest in this work is the fabrication of a 935 nm Distributed Bragg reflector (DBR) laser which can be used to repump Yb ions permitting Doppler cooling. DBR’s can provide output powers in the range of hundreds of milliwatts with stable narrow linewidth operation, with small system size and without the complexity of the external cavity configuration, thus providing an excellent solution for quantum technologies. Furthermore, the development in laser technologies is enabling the scalability and commercial use of quantum technologies where single frequency DBR lasers can be used as a part of a multiwavelength laser platform. In this work we have demonstrated high-power and narrow linewidth operation at 935 nm. The in-house epitaxial design is based on AlGaAs structure including an AlGaInAs active area. The position of the active region is optimized with asymmetric waveguides to enhance the device performance. The lasers are fabricated using metalorganic vapor phase deposition (MOCVD) after which the surface gratings are defined by electron beam lithography (EBL). The high-aspect ratio gratings are etched by inductively coupled plasma reactive ion etching (ICP-RIE). For device optimization purposes the gain medium section lengths, grating periods and cavity lengths were varied to find the optimal performance.