Towards integrated tunable all-silicon free-electron light sources Roques-Carmes, Charles Kooi, Steven E. Yang, Yi Massuda, Aviram Keathley, Phillip D. Zaidi, Aun Yang, Yujia Joannopoulos, John D. Berggren, Karl K. Kaminer, Ido Soljačić, Marin ddc:530 Extracting light from silicon is a longstanding challenge in modern engineering and physics. While silicon has underpinned the past 70 years of electronics advancement, a facile tunable and efficient silicon-based light source remains elusive. Here, we experimentally demonstrate the generation of tunable radiation from a one-dimensional, all-silicon nanograting. Light is generated by the spontaneous emission from the interaction of these nanogratings with low-energy free electrons (2–20 keV) and is recorded in the wavelength range of 800–1600 nm, which includes the silicon transparency window. Tunable free-electron-based light generation from nanoscale silicon gratings with efficiencies approaching those from metallic gratings is demonstrated. We theoretically investigate the feasibility of a scalable, compact, all-silicon tunable light source comprised of a silicon Field Emitter Array integrated with a silicon nanograting that emits at telecommunication wavelengths. Our results reveal the prospects of a CMOS-compatible electrically-pumped silicon light source for possible applications in the mid-infrared and telecommunication wavelengths. Springer Nature 2019 info:eu-repo/semantics/article doc-type:article article http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/21538 Roques-Carmes C, Kooi SE, Yang Y, et al. Towards integrated tunable all-silicon free-electron light sources. <i>Nature Communications</i>. 2019;10. doi:<a href="https://doi.org/10.1038/s41467-019-11070-7">10.1038/s41467-019-11070-7</a> eng info:eu-repo/semantics/altIdentifier/doi/10.1038/s41467-019-11070-7 info:eu-repo/semantics/altIdentifier/e-issn/2041-1723 info:eu-repo/semantics/openAccess