Sci. Adv. 4, eaar3580 (2018)

Single-photon emitters (SPEs) are key components in quantum technology. Using single photons at telecom rather than ultraviolet–visible wavelengths could suppress attenuation losses in optical cables. However, such SPEs have so far been restricted to cryogenic temperatures. Now, Zhou et al. demonstrate single-photon emission at telecom wavelengths from gallium nitride (GaN) defects that generate photons of high purity and brightness at room temperature.

Credit: AAAS

The researchers use a 950 nm diode laser to excite the defects in GaN single-crystal films deposited on a sapphire substrate and observe single-photon emission with wavelengths between 1,085 and 1,340 nm. Though the room-temperature emission was strongly broadened for some defects, other emitters possessed linewidths as narrow as 3 nm. To further increase the brightness of the photon sources, Zhou and co-workers pre-patterned the sapphire substrate with cone-like cavities prior to the GaN deposition. This increased the extraction efficiency and yielded emission with megahertz rates. The reported solid-state SPEs can be easily integrated with on-chip quantum devices.