Kazutaka Nara

100 GHz-32 ch athermal AWG with extremely low temperature dependency of center wavelength

New athermal AWG with 100 GHz-32 ch has been developed. This novel athermal AWG exhibits excellent property in temperature dependency of center wavelength less than /spl plusmn/0.01 nm under the temperature range 0 to 70/spl deg/C.

Ultrasmall PBS-integrated coherent mixer using 1.8%-delta silica-based planar lightwave circuit

A silica-based planar lightwave circuit (PLC) is developed as an optical front-end for polarization-diversity digital-coherent receiver, where polarization-beam splitters and 90-degree optical-hybrid mixers are integrated in a small-size (12mm×12mm) PLC chip employing a relatively large refractive-index difference of 1.8%.

Low loss (/spl sim/1.4 dB) 200 GHz-16ch athermal AWG compact module for metro/access network

We have developed a low loss (/spl sim/1.4dB) 200 GHz-16ch athermal AWG compact module for a metro/access network. A size of the module was achieved a reduction of about 35% in comparison with the conventional module.

Polarization insensitive wideband tunable dispersion compensator with integrated PLC type polarization diversity circuit

We demonstrated a novel polarization insensitive wideband tunable dispersion compensator with integrated PLC type polarization diversity circuit and obtained tunable dispersion range of +/-100 ps/nm and operating bandwidth of 0.6 nm

Low-loss optical transversal programmable filter with symmetrical arrangement of cascade variable couplers using silica-based PLC

An optical transversal programmable filter can realize arbitrary filter characteristics in one circuit and can vary the filter characteristic adaptively, so it is a promising device. This filter consists of a variable splitter for splitting a input light to N paths(taps), variable phase shifters, delay lines and a variable combiner for combining the split lights to an output light. We can obtain the desired filter characteristics by setting up the arbitrary tap coefficients and minimize the principle loss by designing a symmetrical arrangement of the variable splitter and the variable combiner with each other. However, in order to set those, it is necessary to control the circuit characteristics accurately with compensating for the fabrication errors. We fabricated the low loss optical transversal programmable filter with the monitor waveguides and a novel method which adjusts the circuit characteristics and compensates the fabrication errors, using silica-based PLC. And we demonstrated three types of filter spectra having a Gaussian-shape, a flat-top-shape and a flat-top-shape with a low loss ripple adaptively using the one optical transversal programmable filter.

Hybrid integration of semiconductor optical amplifier and silica-based planar lightwave circuit for low polarization dependent gain

We demonstrated a semiconductor optical amplifier hybrid-integrated with a silica-based planar lightwave circuits. With deploying polarization diversity circuit, polarization dependent gain was reduced from 22.9 dB to 1.8 dB in C-band.

High Channel Low Loss Optical Splitter using Silica-based PLC on Quartz Substrate

We have designed and fabricated the 2x32 optical splitter and the 1x64 optical splitter with the low insertion loss <;16.5dB and <;19.3dB, respectively for 1.31μm-band and 1.49μm-1.55μm-band by using silica-based PLC on a quartz substrate.

Athermal AWG Module with Extremely Low Temperature Dependence (≪+/-5pm) of Center Wavelength using Multi-compensating Plates

We successfully fabricated an athermal AWG module with an extremely low temperature dependence using multi-compensating plates. We realized an excellent performance in which the center wavelength shift was ≪+/-5pm from -30 to 70°C.

Semiconductor optical amplifier with polarization diversity for optical interconnect

Optical amplifier will be required for advanced optical interconnect systems to compensate optical signal loss. We propose a hybrid integration of semiconductor optical amplifier with polarization diversity for low polarization dependent gain operation.

Compact and Colorless PLC-Type 1-Bit Delay Line Interferometer for DQPSK Demodulator

A compact and colorless planar lightwave circuit (PLC) type 1-bit delay line interferometer for a differential quadrature phase-shift keying (DQPSK) demodulator is demonstrated by adopting wavelength insensitive couplers with narrow coupling waveguides and novel circuit arrangement suitable for integrated DQPSK receivers. The fabricated interferometer realizes a small chip size and practical properties in both entire C- and L-bands.