Monolithically-integrated distributed feedback laser compatible with CMOS processing

An optically-pumped, integrated distributed feedback laser is demonstrated using a CMOS compatible process, where a record-low-temperature deposited gain medium enables integration with active devices such as modulators and detectors. A pump threshold of 24.9 mW and a slope efficiency of 1.3 % is demonstrated at the lasing wavelength of 1552.98 nm. The rare-earth-doped aluminum oxide, used as the gain medium in this laser, is deposited by a substrate-bias-assisted reactive sputtering process. This process yields optical quality films with 0.1 dB/cm background loss at the deposition temperature of 250 ◦C, and therefore is fully compatible as a back-end-of-line CMOS process. The aforementioned laser’s performance is comparable to previous lasers having gain media fabricated at much higher temperatures (> 550 ◦C). This work marks a crucial step towards monolithic integration of amplifiers and lasers in silicon microphotonic systems.