| Photonic crystals (PhCs) offer precise control over light propagation on a microscopic scale because of the unique properties of the photonic band gap (PBG). Various PhC-based wavelength-division demultiplexers (WDDMs) utilizing different coupling methods to separate individual wavelength signals have recently been reported. These devices are above an order of magnitude more compact than conventional WDDMs such as arrayed-waveguide gratings, and may be implemented in photonic integrated circuits for telecommunication applications. However, the quality of performance attributed to these PhC WDDMs has generally been limited, particularly with respect to spectral characteristics and demultiplexed channel counts.; A novel variety of PhC coupled-cavity waveguide, which we have designed and designated an alternating-defect coupled-cavity waveguide (AD-CCW), features a channel drop filter-induced coupling mechanism to reduce eigenmode splitting and effect very narrow spectral linewidth transmission. Four- and six-channel demultiplexers incorporating AD-CCWs have been designed based on two-dimensional PhC slabs perforated by a triangular lattice of air holes, and are analyzed. Finite-difference time-domain (FDTD) simulations evidence relatively uniform transmission peaks at around 1.55 mum that exhibit ∼1 nm linewidths, with spectral resolution of 275 GHz or ∼2 nm (tunable through varying relative AD-CCW dimensions) demonstrated by the 6-channel device. Additionally, investigation and foundational modeling results are included of a vertically-oriented multilayer PhC resonant cavity structure designed to utilize PBG effects to provide lateral optical confinement for both transverse (betaz = 0) and out-of-plane modal propagation, for application in quantum well modulators. |
