Three-dimensional photonic crystal waveguides and resonators by unit cell size modulation

Abstract

The Cu-based interconnect is a major bottleneck for sustaining technological advances in semiconductor integrated circuits. Matured optics technology may be able to resolve this challenge. Optics can provide high-speed, wavelengthdivision- multiplexing signals with the capability of interfacing optics with electronics through EO and OE conversion- directly-modulated laser, external modulator, and photodiode. An optical waveguide is a major building block for optical interconnects technology. A three-dimensional photonic crystal may provide single-mode, low-loss, group-velocitydispersionless, and compact waveguides. We report designs of double-heterojunction optical waveguides in a threedimensional photonic crystal. Compact optical waveguide modes are induced by modulating unit cells onedimensionally or two-dimensionally. One way to do this is to modulate the unit cell size. A well-type waveguide structure is formed by modulating the lattice constant of woodpile in one direction. For some 1D double-heterojunction geometries, light propagation becomes non-dispersive in the space domain, i.e. light is self-collimated along certain directions within the well plane. Next, two-dimensional unit-cell-modulation is applied to a 3D photonic crystal for exciting wire-type waveguide modes, for which light propagates along the horizontal or vertical wire. As a result, light may be guided in the same level or into different levels. The propagation properties, such as group velocity, and waveguide group velocity dispersion, are also analyzed in this work.