For the first time, researchers have built a quantum cascade laser (QCL) on silicon. Typically, silicon photonic devices operate at near-infrared wavelengths, which limits their practical applications to data transmission and telecommunications. However, the new device could utilize longer wavelengths, which opens the possibility for a wide range of sensing and detection applications.
To build the QCL on silicon, the researchers had to develop both a new kind of laser on silicon and a new silicon waveguide. Alexander Spott, who led the research from University of California, Santa Barbara, explained, “We built a type of waveguide called a SONOI waveguide [silicon-on-nitride-on-insulator], which uses a layer of silicon nitride [SiN] underneath the silicon waveguide, rather than just SiO2.”
The researchers will present their findings at the Conference on Lasers and Electro-Optics in San Jose, California on June 9, 2016. Looking ahead, the team plans to improve the device’s heat dissipation to make it powerful and efficient enough to make make continuous-wave QCLs on silicon. The new device eliminates the need for an external light source for mid-infrared silicon photonic devices or photonic circuits. Spott said:
This brings us closer to building fully integrated mid-infrared devices on a silicon chip, such as spectrometers or gas sensors. Silicon is inexpensive, the fabrication can be scaled up to significantly reduce the cost of individual chips, and many small devices can be built on the same silicon chip for example multiple different types of sensors operating at different mid-infrared wavelengths.