High transmission through a 90° bend in a polarization-independent single-mode photonic crystal waveguide

High-purity transmission of a slow light odd mode in a photonic crystal waveguide.

We demonstrate a novel scheme to control the excitation symmetry for an odd mode in a photonic crystal waveguide and investigate the spectral signature of this slow light mode. An odd-mode Mach-Zehnder coupler is introduced to transform mode symmetry and excite a high-purity odd mode with 20 dB signal contrast over the background. Assisted by a mixed-mode Mach-Zehnder coupler, slow light mode b...

Second order sensitivity analysis for a photonic crystal waveguide bend

Sensitivity analysis provides important information on the tolerance to fabrication imperfections for any designed devices. Standard sensitivity analysis relies on the first order partial derivatives of a response function of the device with respect to the design parameters. These derivatives are also useful in the device optimization process when a gradient based optimization method is used. T...

Bandwidth optimization of single-polarization single-mode photonic crystal fibers

We present an algorithm for computing single-polarization single-mode (SPSM) photonic crystal fibers with optimal bandwidth. Our approach is a topology optimization strategy based on convex conic optimization combined with a subspace method. The original problem of maximizing the bandwidth between the fundamental guided mode and the higher order unguided modes is reformulated as a problem of op...

90°-turns with polarization-independent single-mode waveguide on silicon-on- insulator for telecommunication wavelengths

Topology Design and Fabrication of an Efficient Double 90 Photonic Crystal Waveguide Bend

We have designed and fabricated a novel 90 bend in a photonic crystal waveguide. The design was obtained using topology optimization and the fabricated waveguide displays a bend loss for transverse-electric-polarized light of less than 1 dB per bend in a 200-nm wavelength range.