Few-fJ/bit data transmissions using directly modulated lambda-scale embedded active region photonic-crystal lasers

A low operating energy is needed for nanocavity lasers designed for on-chip photonic network applications. On-chip nanocavity lasers must be driven by current because they act as light sources driven by electronic circuits. Here, we report the high-speed direct modulation of a lambda-scale embedded active region photonic-crystal (LEAP) laser that holds three records for any type of laser operated at room temperature: a low threshold current of 4.8 mA, a modulation current efficiency of 2.0 GHz mA and an operating energy of 4.4 fJ bit. Five major technologies make this performance possible: a compact buried heterostructure, a photonic-crystal nanocavity, a lateral p–n junction realized by ion implantation and thermal diffusion, an InAlAs sacrificial layer and current-blocking trenches. We believe that an output power of 2.17 mW and an operating energy of 4.4 fJ bit will enable us to realize on-chip photonic networks in combination with the recently developed highly sensitive receivers.