Seiichi Takayama

Experimental demonstration of complete photonic band gap in two-dimensional photonic crystal slabs

The realization of a photonic band gap (PBG)—not only for transverse electric (TE), but also transverse magnetic (TM)-like polarization modes in two-dimensional photonic crystal slab—is of interest for various applications. Such a complete PBG has been investigated theoretically in two-dimensional structures of which thickness is infinity. However, a complete PBG has not been demonstrated in feasible two-dimensional slab structure. In this letter, we propose two-dimensional photonic crystal slabs consisting of a triangular lattice of triangular air holes to achieve a complete PBG, and report the transmission spectra of fabricated samples. The results indicate that the degeneracy between the first and second band at the J point for TM-like polarization mode is solved, and PBG for TM-like polarization mode is obtained. Finally, we confirm the overlap of PBG between TE- and TM-like polarization modes.

Polarization mode converter based on 2D photonic crystal slab

A polarization mode converter based on 2D photonic crystal slab is proposed and investigated. It is shown that efficient mode conversion is possible for wide wavelength range by only forming a couple of tilted air-hole arrays

A Polarization Diversity Two-Dimensional Photonic-Crystal Device

2-D photonic crystals (2-D PCs) are expected to enable ultrasmall and highly functional photonic devices to be developed. However, 2-D PCs have a large polarization dependency, which can be an important issue depending on the type of application. To address this matter, we propose a method to realize a polarization diversity operation in a PC. Initially, an ultrasmall PC polarization converter that utilizes 45° tilted airholes is considered. A polarization-independent add-drop filter using this polarization converter is then described, and the operation is experimentally demonstrated.