Tetsuyoshi Ishii

Second- and third-order dispersion compensator using a high-resolution arrayed-waveguide grating

We have proposed a dispersion compensation scheme that uses a high-resolution arrayed-waveguide grating (AWG). When the diffraction order of the AWG is 59 and the number of waveguides in an arrayed-waveguide is 340, the calculated maximum second- and third-order dispersion compensation range is 18.0 ps/nm and /spl plusmn/6.0 ps/nm/sup 2/, and 1100 ps/nm and /spl plusmn/937.5 ps/nm/sup 2/, for a 1 ps-pulse and a 12.5 ps-pulse, respectively. In experiments, second-order dispersion (-0.8 to +5.2 ps/nm) is effectively compensated for 1,1-ps pulses; and. Pulse compression by third-order dispersion compensation is successfully demonstrated.

Fast tunable optical filter using cascaded Mach-Zehnder Interferometers with apodized sampled gratings

We demonstrate a novel tunable optical filter using cascaded Mach-Zehnder interferometers with apodized sampled gratings (ASGs). The ASGs are fabricated using an InGaAsP-InP deep-ridge waveguide with vertical-groove surface grating to obtain a high extinction ratio by sidelobe suppression. The proposed filter exhibits the total free-spectral range of 16 nm, an extinction ratio of 20 dB, and a 3-dB transmission bandwidth of 32 GHz.

Second- and third-order dispersion compensation using a high resolution arrayed-waveguide grating

Second-order dispersion (6.0 ps/nm) is effectively controlled by time-space conversion using an arrayed-waveguide grating (AWG) and pulse compression by third-order dispersion compensation is successfully demonstrated.

High-Speed Wavelength-Tunable Optical Filter Using Cascaded Mach–Zehnder Interferometers With Apodized Sampled Gratings

A high-speed wavelength-tunable optical filter is a key device for selecting different wavelength optical packets on a packet-by-packet basis in a photonic packet switching system. In this paper, we describe a high-speed tunable filter using apodized sampled gratings which can achieve the required filter characteristics at low cost. A sampled grating structure that exhibits a comb-like filter response is adopted to obtain a wide tuning range, implemented in InGaAsP-InP deep-ridge waveguides with vertical-groove surface gratings. In addition, apodization is applied to the sampled grating to achieve a high extinction ratio. We fabricate the filter by integrating the sampled gratings within Mach-Zehnder interferometers. The filter exhibits a tuning range of 16 nm, an extinction ratio of 20 dB, a 3-dB transmission bandwidth of 32 GHz, and a switching time of less than 8 ns.

Short Cavity DBR Laser Using Vertical Groove Gratings for Large-Scale Photonic Integrated Circuits

We present a novel compact distributed Bragg reflector (DBR) laser using InP-InGaAsP deep ridge waveguides with vertical groove gratings. Stable single-mode laser operation was achieved with an active cavity length down to 25 mum and a threshold current of 14 mA. The devices are promising building blocks in large-scale photonic integrated circuits because of their simple structure and low power consumption.

Apodised chirped gratings using deep-ridge waveguides with vertical-groove surface gratings

Apodised chirped gratings based on InGaAsP/InP deep-ridge waveguides with vertical-groove surface gratings were fabricated. Reflectivity ripple and group delay ripple were reduced from around 4dB to 1 dB and from around 5 ps to 2 ps, respectively, by apodisation over a wavelength range of around 20 nm.

Fullerene incorporated nanocomposite resist systems for practical nano-fabrication

We propose a nanocomposite resist system that incorporates sub-nm fullerene C60 or C70 into a conventional resist material as a practical nanometer range resist system. Fullerene molecules show chemical and physical resistant characteristics, and their incorporation reinforces the original resist film, leading to substantial improvements in resist performance: etching resistance, pattern contrast, mechanical strength, and thermal resistance. A nanocomposite resist system based on an positive-type electron beam resist, ZEP520, and its application to the fabrication of X-ray masks, diffractive grating elements, nano-printing molds, and quantum dots are presented.