Our goal is to develop practical, electrically-controlled low-threshold nanocavity lasers and modulators for optical interconnects, telecommunications, and sensing applications.
Nanocavities can confine light in volumes smaller than a wavelength cubed while maintaining moderate to high quality factors. Such localization of light allows us to design lasers and modulators with very small active regions, enabling fast, low-energy electrical switching. Additionally, localization of light in a nanocavity increases the spontaneous emission rate into the cavity mode, reducing the laser threshold and further increasing achievable modulation rates.
We have demonstrated a record low threshold electrically-driven photonic crystal nanocavity laser at 150K using InAs quantum dots in a suspended GaAs membrane as a gain medium. We have also shown ultrafast direct modulation of a single-mode photonic crystal LED at room temperature as well as nanobeam cavity LEDs in the same material system, and have also demonstrated an ultralow-power fiber-coupled modulator using a passive GaAs photonic crystal structure. All of these devices were electrically controlled with a lateral p-i-n junction formed via ion implantation into GaAs, a method we hope to extend to other materials in a simliar configuration.
Our current work is focused on creating a low-threshold electrically driven nanocavity laser capable of operating at room temperature. We are working to counteract the decreased room-temperature gain of InAs quantum dots in GaAs, as well as exploring the higher gain and lower surface recombination offered by the InP material system.