Yasuhiro Hida

Polymer waveguide thermooptic switch with low electric power consumption at 1.3 mu m

A polymer waveguide thermooptic 2*2 switch with low electric power consumption is demonstrated. The switch consists of a Mach-Zehnder interferometer with Cr thin-film heaters. The waveguides are fabricated using acrylic polymers synthesized from deuterated methacrylate and deuterated fluoromethacrylate monomers. The total insertion loss of the switch is 0.6 dB at a wavelength of 1.3 mu m, including fiber coupling losses and waveguide losses. The switching power is as low as 4.8 mW, and the rise and fall times are both 9 ms.<<ETX>>

Influence of humidity on refractive index of polymers for optical waveguide and its temperature dependence

Humidity dependence of the refractive index of deuterated polymethylmethacylate (d-PMMA) is examined at a wavelength of 1.3 μm using the return loss method. The refractive index of d-PMMA increases as humidity increases at room temperature, while it decreases as humidity increases at temperatures higher than 60 °C. This humidity dependence was ascribed to the counterbalance between moisture sorption and swelling. Some hydrophobic polymers, such as silicone resin and fluorinated epoxy resin were affected by humidity to a lesser degree than d-PMMA.

Influence of Temperature and Humidity Change on Optical Waveguide Circuits Composed of Deuterated and Fluorinated Methacrylate Polymers

We fabricated a 57 cm long waveguide circuit and an arrayed-waveguide-grating (AWG) demulti/multiplexer using deuterated and fluorinated methacrylate polymers, and examined the influence of environmental change on their transmission characteristics. A 57 cm waveguide with a loss of 0.1 dB/cm at 1.3 µ m exhibited a slight loss increase of 0.03 dB/cm when the humidity was raised from 13 to 98%RH and a negligible loss change when the temperature was increased to 70° C. On the other hand temperature and humidity changes respectively caused wavelength shifts of 0.9 and 5 nm in the transmission peaks of an AWG with an adjacent channel spacing of 0.65 nm. Furthermore we confirmed that the influence of the humidity resulted from water sorption in the waveguide polymers.

Fabrication of silica-on-Si waveguide with higher index difference and its application to 256 channel arrayed waveguide multi/demultiplexer

Improved techniques were used to fabricate a silica-on-Si waveguide with a higher core-to-cladding index difference and a 2 mm bending radius. A 256 channel and 25 GHz spacing arrayed-waveguide multiplexer with low loss and low crosstalk was successfully fabricated for the first time using the waveguides.

Silica-based 1 x 32 splitter integrated with 32 WDM couplers using multilayered dielectric filters for fiber line testing at 1.65 μm

We propose an integrated splitter with reflection-type couplers for combining the modules used for passive double star transmission and fiber line testing systems. We fabricated a silica-based 1/spl times/32 splitter with an array of 32 1.3-1.55/1.65 /spl mu/m wavelength-division-multiplexing couplers using planar lightwave circuit technologies and by embedding multilayered dielectric filters in cross-waveguides located in the splitter outputs. We developed a 64-fiber array block to connect the 64 coupler input/output ports. We achieved low loss characteristics of /spl les/17.5 dB at 1.31 and 1.55 /spl mu/m for the splitter and of /spl les/2.2 dB at 1.65 /spl mu/m for the couplers.

Moisture-induced drift in thermo-optic phase shifters composed of deuterated and fluorinated methacrylate polymer waveguides

Using deuterated and fluorinated methacrylate polymer waveguides, we fabricated thermo-optic phase shifters that require a small electric power of 10 mW to cause a pi phase shift. The phase shifters had a phase drift that was greater at higher humidity and that was saturated in approximately 10 min. This phenomenon is ascribed to the moisture desorption-sorption of the waveguide polymers caused by heating-cooling on the basis of experimental results on the relationships among waveguide temperature increase, relative humidity, and moisture sorption of the waveguide polymers. This conclusion is supported by the calculation of temperature and moisture distribution in the waveguide when the thin-film heater is heated.

Ultra-high density AWGs composed of super-high /spl Delta/ PLCs

Summary form only given. Planar lightwave circuits (PLCs) incorporating arrayed-waveguide gratings (AWGs) are excellent in terms of circuit density, design flexibility, multi-channeling and mass-production, and are widely deployed in optical networks. This paper reviewed our recent progress on ultrahigh density AWGs composed of SH /spl Delta/ PLCs, including a large-scale AWG chip (400 channels) and module (256 channels), and a small size AWG with low-loss (<0.2 dB/pt) single-mode fiber (SMF) coupling by forming spot size converters (SSCs) in the AWG. These SH /spl Delta/ PLC technologies are promising in terms of providing the optical devices necessary for more broadband and cost-effective networks.

Wavelength demulti/multiplexers with non-sinusoidal filtering characteristics composed of point-symmetrically connected Mach-Zehnder interferometers

Waveguide-type wavelength demulti/multiplexers (WDM) with non-sinusoidal filtering characteristics for optical communication systems are demonstrated using Mach-Zehnder interferometers, (MZI) composed of point-symmetrically connected MZI optical couplers. Three types of WDM, (1) a 1.3/1.55 μm wide-band WDM, (2) a partially-coupled 1.3/1.55 μm wide-band WDM for fiber line testing, and (3) a 1.3 & 1.55/1.65 μm WDM were designed by appropriately setting the wavelength characteristics of the directional couplers and the path differences of the waveguide arms in the MZI-WDMs. These WDMs were fabricated using silica-based planar lightwave circuit technology, and the measured results were in good agreement with the designed characteristics.

Novel polarization-insensitive AWG with undercladding ridge structure

We propose a novel method for realizing a polarization-insensitive silica-based AWG with an undercladding ridge. We successfully demonstrated low polarization dependence (<0.01 nm) without any optical degradation by using a slightly longer etching time during core formation.

Digital Thermooptic Switch Formed Using Silicone Resin Waveguides

Polymer waveguides made with deuterated silicone resin have a low propagation loss of 0.5 dB/cm at 1.55 µ m, and offer long term stability in the humid conditions of 90% RH at 75° C. A digital thermooptic switch formed using the silicone resin waveguides exhibits an insertion loss of 30 dB at 1.55 µ m. This switch is insensitive to wavelengths in the range of 1535–1620 nm, and operates properly even at 80° C.