Phase-Matched Second Harmonic Generation With On-Chip GaN-On-Si Microdisks

We demonstrate phase-matched second harmonic generation in GaN microdisks integrated on a photonic circuit on silicon. Phase matching between TM modes is evidenced by varying the disk diameter by steps of 8 nm, one thousand smaller than their diameter. An enhanced conversion efficiency is obtained under cw near infrared excitation when both pump and harmonic modes are resonant with whispering gallery modes (Q factors around 10000) and orbital momentum is conserved (Δm = 0 where m is the azimuthal number). We will compare the second harmonic conversion efficiency in GaN and AlN microdisks to the one obtained with other III-V materials.