Monolithically-integrated distributed feedback laser compatible with CMOS processing
Emir Salih Magden, Nanxi Li, Purnawirman, Jonathan D. B. Bradley, Neetesh Singh, Alfonso Ruocco, Gale S. Petrich, Gerald Leake, Douglas D. Coolbaugh, Erich P. Ippen, Michael R. Watts, and Leslie A. Kolodziejski
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.