High-speed nanoLEDs for chip-scale communication

Fast and efficient light generation and transport are at the heart of modern on-chip optical communication and information processing technologies. Next generation on-chip light sources must have a high modulation bandwidth and low energy consumption while maintaining a small footprint to be competitive. Enabled by metal-cladded nanocavities, fast subwavelength light emitters in the form of both lasers and LEDs have been analytically or experimentally demonstrated. From the modulation bandwidth perspective, nanolasers are ultimately limited by gain compression at high injection currents. From the energy efficiency perspective, nanolasers are inefficient due to the required high injection current to compensate for the losses in order to reach the lasing threshold. In contrast, nanoLEDs can simultaneously have Purcell effect enhanced speed, high energy efficiency, and output power that is above the thermal noise limit. This brief review aims to bolster, in a comparative approach, rationales of why nanoLEDs are a competitive alternative to nanolasers as light sources in chip-scale optical communication systems.