Emission Characteristics of All-Silicon Distributed Feedback Lasers with a Wide Gain Range

With the development of nanomanufacturing methods, the manipulation of photons down to the nanoscale in silicon integrated optical chips has become a feasible and promising solution for next-generation data processing as electronic chips reach their limit. As an essential active device that generates photons for all other working photonic components, silicon lasers are the last barrier to achieve silicon integrated optical chips. Although optical gain in silicon nanocrystals (Si-NCs) was observed in 2000, the progress in realizing all-Si lasers has been very limited due to the inferior optical gain compared to traditional gain materials. In this paper, highly luminescent thin films of Si-NCs with a photoluminescence quantum yield of 57% are developed. The broadband photoluminescence covers the wavelength range from 650 to 900 nm, and wide-range optical gains are identified, indicating the feasibility of a tunable laser. Distributed feedback (DFB) all-Si lasers are fabricated using these thin films and pumped by femtosecond pulses. Various characteristic lasing behaviors are observed. Additionally, three different DFB grating periods are selected, and the lasing peak can be tuned by over 100 nm. The lasing thresholds range from 8.3 to 53.3 MW/cm². The linewidths of lasing peaks are less than 2 nm.