Strain-tunable Photonic Band Gap Microcavity Waveguides at 1.55 μm Personnel

Concept and Key Idea Photonic-bandgap microcavities in optical waveguides have demonstrated cavity resonances at wavelengths near 1.55 μm band, quality factors on the order of 300, and modal volume at 0.055 μm3 in high-index contrast Si/SiO2 waveguides and GaAs air-bridge waveguides. Applications include zero-threshold microlasers, filters and signal routers. For tunability in Si microphotonic platforms, thermal actuation is often utilized. Compared to thermo-optics, the novel strain-tuning via thin-film piezoelectric micro-actuators provides a significantly faster response, lower power consumption and better localization of tunability. This level of integration would permit dynamic reconfiguration of the cavity resonance and band-edges, fine-tuning for fabrication mismatches, and active compensation of device arrays to external disturbances. We have designed and fabricated the first tunable photonic-bandgap microcavities in optical waveguides, with the strain modulation via thin-film piezoelectric actuators on deformable membranes. Cavity resonance tunability, with sub-nanometer lattice control, is designed through perturbation on FDTD computations. Device fabrication integrates X-ray nanolithography, piezoelectric micro-actuators and bulk micromachining.