Applied Physics Seminar

Low mode-volume, high quality (Q) factor optical microcavities are promising for nonlinear optical frequency conversion devices, as they have the potential to reach similar conversion efficiencies to traditional optical cavities, but in significantly more compact devices. In particular, if the optical mode volume becomes small compared to the material nonlinear coherence length, the phase matching condition is replaced by the requirement of large overlap between the relevant optical modes. The experimentally achieved efficiency of three wave mixing processes in photonic crystal cavities in materials with second order nonlinear susceptibility (χ(2)) has been limited by the difficulty of engineering multiple high quality factor modes with a high degree of overlap.



In this talk, I will first present simulations and experiments demonstrating second harmonic generation in GaAs photonic crystal cavities. We compare conversion efficiencies and modal structure for frequency conversion in photonic crystal cavities. We further design and characterize photonic crystal cavities with multiple high Q resonances and large frequency separations of up to 800 nm for high efficiency frequency conversion. We demonstrate sum frequency conversion from 1.3 um to 780 nm using one such design.