Published in: OPTO SPIE 2024
Authors: Luukas Kuusela, Timo Aho, Riina Ulkuniemi, Mika Mähönen, Jussi Hämelahti, Andreas Schramm, Soile Talmila, Pekko Sipilä, Petteri Uusimaa
Lasers are a key enabling technology in the field of quantum computing, quantum sensing and quantum metrology. These applications require technically challenging properties from the lasers in use, such as stable and precisely controlled wavelength, up to watt level output power, and a narrow linewidth. Semiconductor diode lasers offer a very compact size, low power consumption, as well as scalability of cost and manufacturing volume due to their wafer scale manufacturing process. The monolithic integration of frequency selection on-chip in Distributed Bragg reflector (DBR) lasers offers advantages such as higher robustness, reduced system complexity and smaller size compared to external cavity frequency selection configurations. Thus, DBR lasers provide an optimal solution for a compact narrow linewidth laser source for selected quantum applications. Bandgap engineering of semiconductor gain media enables emission across the spectrum from UV to mid-IR. Wavelengths matching atomic transitions in the 7xx nm wavelength region include 760 nm and 770 nm for Yb, and 780 nm and 795 nm for Rb. In this work we describe the design, manufacturing, and performance of DBR lasers in the 7xx nm wavelength regime. The effects of key device design parameters are investigated to optimize the device performance. These include emitter width, gain and grating length, grating duty cycle, and residual layer thickness. To further scale the laser output power, tapered amplifiers are manufactured and characterized. The lasers are integrated into a laser system platform containing optical isolation, fiber coupling, low-noise laser drivers and temperature controllers. The system includes features such as compact footprint, controlled environment, cloud-connectivity and predictive maintenance.