Hiroaki Okano

Athermal and center wavelength adjustable arrayed-waveguide grating

Athermal and center wavelength adjustable AWGs with flat-top spectral responses are proposed. Low temperature sensitivity /spl sim/0.0013 nm//spl deg/C and precise center wavelength control less than 0.02 nm are demonstrated without additional loss and crosstalk penalty.

Novel architecture of wavelength interleaving filter with Fourier transform-based MZIs

A novel wavelength interleaving filter (interleaver) has been demonstrated with Fourier transform-based Mach Zehnder interferometers (MZIs). The interleaver works as two independent 1/spl times/2 interleavers by sharing their delay lines and couplers.

Loss Reduction of GeO2-Doped Silica Waveguide with High Refractive Index Difference by High-Temperature Annealing

The effect of a GeO2-doped core on high-temperature annealing has been investigated to reduce the propagation loss of a waveguide device with high refractive index difference (Δ). A SiO2–GeO2 waveguide core was prepared on a fused silica substrate by rf magnetron sputtering and reactive ion etching. With increasing the annealing temperature, the roughness of the core side-wall gradually disappears and the rectangular core gradually becomes rounded. The effect of smoothing and rounding the cores was a significant reduction of the scattering loss, and moreover, it enabled the complete embedding of narrow gaps between cores in cladding glass using conventional plasma chemical vapor deposition. The propagation loss of the waveguide with a Δ of 1.5% was 0.07 dB/cm at 1.55 µm wavelength, the effect of which was demonstrated in the fabrication of an arrayed-waveguide grating demultiplexer.

Low loss and wide passband arrayed waveguide grating demultiplexer

New arrayed waveguide gratings (AWGs) are proposed with asymmetry slab waveguides for combined optical performance of low insertion loss and wide passband. The predicted performance is demonstrated using 16 channel, 100 GHz channel spacing AWGs.

Passive aligned hybrid integrated optical module using planar lightwave circuit platform

In order to obtain low cost and high performance wavelength division multiplexing (WDM) transceiver module, novel techniques have been proposed on the formation of index marks on the Si bench of the planar lightwave circuit (PLC) platform for passive alignment and the trench formation for inserting the 1.3/1.5 /spl mu/m WDM dielectric filter. These techniques have been proved to be useful for realizing hybrid integrated optical modules based on the PLC platform.

Integration and Evaluation of Multichannel Photonic Crystal Wavelength Filters Consisting of Autocloned Ta2O5/SiO2 Multilayer Thin Films

We report on the fabrication of multichannel photonic crystal (PC) wavelength filters and their evaluation at wavelength division multiplexing (WDM) wavelengths. The devices utilize three-dimensional (3D) PCs consisting of Ta2O5/SiO2 multilayer thin films fabricated by the autocloning method. The 3D PCs serve as Bragg mirrors in the devices and finite-difference time-domain (FDTD) simulations of these mirrors revealed that their Bragg wavelength shifted by +19.8 nm as the in-plane lattice constant of the crystal increased from 400 nm to 800 nm. We fabricated these filters with a Ta2O5 cavity and obtained a wavelength shift of +24.0 nm.

Insertion loss reduction by optimization of waveguide perturbations

We describe a method to significantly decrease insertion loss in waveguide-based devices, including optical cross-connects. Reductions as large as 3 dB are obtained in 32/spl times/32 switches by optimizing the dielectric perturbations.

Wavelength splitters for DWDM systems

We have demonstrated chromatic dispersion free DWDM wavelength splitters by novel configuration of monolithically integrated three identical circuits, which consist of Fourier transform-based Mach Zehnder interferometers (MZI)s.

Performance improvements in bubble-actuated photonic cross-connect switches

Photonic cross-connect switches have many advantageous features that should enable their use in optical fiber communications systems. One such primary feature is their transparency to bit rate, coding protocol, and wavelength. However, where the cost and size requirements of optical amplification may be a serious consideration, intrinsic insertion loss may limit the usefulness of some photonic switch approaches, especially for large port counts.

Thermo-optically switchable drop filter with photoinduced Bragg grating on silica-based waveguide

Summary form only given. In summary, a novel switchable drop filter has been proposed and demonstrated with photoinduced Bragg grating on a silica-based waveguide with the heater power consumption of 0.124 W (a driving current is 60 mA). Good switching responses were obtained by 0.4-nm shifts of Bragg wavelength.