Spatial full-duplex light communication achieved with a monolithic non-suspended multicomponent system.

The multiple-quantum-well diode (MQW-diode) inherently exhibits simultaneous behavior because of the overlap between the emission spectra and spectral responsivity of the MQW-diode. This feature makes it feasible to form a full-duplex light communication system when two identical MQW-diodes separately function as a transmitter and a receiver at the same time. To verify spatial full-duplex light communication, we fabricated and characterized a monolithic multicomponent system by integrating two InGaN waveguide-based MQW-diodes into a single chip. A 5-μm-wide air gap between two MQW-diodes was manufactured for precise alignment, which could yield spatial light transmission and coupling. Spatial co-time co-frequency full-duplex (CCFD) light communication was experimentally demonstrated using the monolithic multicomponent system, a self-interference cancellation scheme was used to extract the superimposed signals, and a full-duplex audio transmission experiment was performed, opening a promising route toward parallel information processing via free space based on the simultaneous light-emitting and light-detecting phenomenon of the MQW-diode.