• Three-dimensional photonic crystal nanolasers
• Single-mode waveguide optical isolators
• Current-injection photonic crystal lasers

Three-dimensional (3D) photonic crystals are structures in which the permittivity is periodically modulated in three directions with a period comparable to the wavelength of light. When the modulation contrast is large, 3D photonic crystals with certain lattice structures possess a complete photonic band gap (PBG), a frequency range in which the light propagation is prohibited in all directions regardless of the polarizations. This provides a means of molding light at the physical limit.

In my research, I design, fabricate and characterize low-loss and compact 3D photonic crystal nanocavities and waveguides.

1. Woodpile photonic crystal nanocavity designs

Compact ultra-high-Q modes are designed in a woodpile photonic crystal by modulating the unit cell size along a low-loss waveguide in a complete PBG. The Q factor increases exponentially with the number of unit cells without saturation in the range of analysis. With different waveguide modes, three resonator modes are designed: monopole mode, dipole mode and quadrupole mode.

In order to form an optical isolator, time reversal and spatial inversion symmetries need to be broken. We proposed a single-mode waveguide optical isolator based on propagation direction dependent cut-off frequency. Non-reciprocal (magnetic) material is included in the waveguide to break time-reversal symmetry, and the spatial inversion symmetry is broken by distributing magnetic material non-uniformly in the waveguide's cross-section.