All-optical guided resonance tuning in hybrid GaN/Si microring induced by non-radiatively trapped injected hot electrons.

Advanced Si/III-V nanophotonics that emerged in the last decade has already founded the on-chip optical interconnect technology for future integrated systems on chip. New possibilities of light-on-chip applications beside signal transmissions, such as, all-optical sensing, have been given but small attention. Here, all-optical ultraviolet (UV)-sensitive guided resonance tuning in a hybrid GaN/Si microring resonator (HMR) was studied. Resonance redshifting by free-space UV pumping resulted in a 12 dB guided-mode modulation at the 1560 nm telecommunication wavelength. Investigations by experiments, theory, and simulations indicated the origin of the tuning mechanism from hot-electron heat extraction via defects-assisted non-radiative recombinations and electron-phonon interactions. A photothermal tuning efficiency of 73 pm/mW was attained at a pump power of 850 μW, thank to photothermal energy directly generated in the HMR. The UV-sensitive visible-blind all-optical tuning in the HMR may benefit all-optical UV sensing for the optical data era to come.