Satoki Kawanishi

Absolutely single polarization photonic crystal fiber

An optical fiber that guides only one polarization mode of a light signal is realized by using highly birefringent pure silica photonic crystal fiber. The fiber guides only one polarization mode at wavelengths longer than 1450 nm. A polarization dependent loss of 196 dB/km with a 28 dB/km transmission loss is achieved at a wavelength of 1550 nm.

Ultrahigh-speed clock recovery with phase lock loop based on four-wave mixing in a traveling-wave laser diode amplifier

A new phase lock loop (PLL) is proposed and demonstrated for clock recovery from an ultrahigh-speed time-division multiplexed (TDM) optical signal. A traveling-wave laser-diode amplifier (TW-LDA) is used as a phase detector, and the cross-correlation component between the optical signal and an optical clock pulse train is detected as a four-wave-mixing (FWM) signal generated in the TW-LDA. A timing clock from a TDM signal is extracted as a prescaled electrical clock, and this prescaled clock is directly recovered from a randomly modulated TDM optical signal. A prescaled 6.3 GHz clock is successfully extracted from a 100 Gb/s signal using the timing comparison output obtained as the cross-correlation between the optical signal and a short (<10 ps) 6.3 GHz optical clock pulse train in the generated FWM light. A comparison of the PLL phase noise with a previously reported gain modulation method is also shown, and the possibility of the Tbit/s operation of this PLL is also considered in the experiments.

Supercontinuum generation at 1.55 µm in a dispersion-flattened polarization-maintaining photonic crystal fiber

We demonstrate the generation of symmetrical supercontinuum of over 40 nm in the 1.55 m region (1540 - 1580 nm) by injecting 1562 nm, 2.2 ps, 40 GHz optical pulses into a 200 m-long, dispersion-flattened polarization-maintaining photonic crystal fiber. The chromatic dispersion and dispersion slope of the fiber at 1.55 m are -0.23 ps/km/nm and 0.01 ps/km/nm2, respectively. This is the first report of 1.55 m band supercontinuum generation in a dispersion-flattened and polarization-maintaining photonic crystal fiber.

All-optical flip-flop circuit composed of coupled two-port resonant tunneling filter in two-dimensional photonic crystal slab

We propose an optical flip-flop circuit composed of two-port resonant-tunneling filters based on a two-dimensional photonic crystal slab with a triangular air-hole lattice. This circuit can function as an optical digital circuit that synchronizes input data with a clock. In this report, we demonstrate that this circuit can achieve a fast operating speed with a response time of about 10 ps and a low operating power of 60 mW by employing a two-dimensional FDTD calculation.

Dispersion slope equalizer for dispersion shifted fiber using a lattice-form programmable optical filter on a planar lightwave circuit

This paper reports an integrated-optic dispersion slope (third-order dispersion) equalizer for dispersion shifted fiber which employs a lattice-form programmable optical filter on a planar lightwave circuit (PLC). This dispersion slope equalizer consists of nine symmetrical interferometers interleaved with eight asymmetrical interferometers. The performance of the equalizer is evaluated numerically. We confirm experimentally that this equalizer is effective in reducing the pulse waveform deterioration caused by the dispersion slope. In addition, the equalizer improves the power penalty of a 200-Gb/s, 100-km, time-division multiplexed optical transmission experiment.

Signal-to-noise ratio analysis of 100 Gb/s demultiplexing using nonlinear optical loop mirror

This paper investigates experimentally and theoretically the signal-to-noise ratio (SNR) characteristics of 100 Gb/s all-optical demultiplexing using a nonlinear optical loop mirror (NOLM). The analysis takes into account two effects that degrade the SNR associated with NOLM demultiplexing. First is channel crosstalk originating from the leakage of nontarget channels. Second is the intensity fluctuations of demultiplexed signals caused by the combined effects of timing jitter and a profile of the switching window. Considering these two effects, power penalties associated with NOLM. Demultiplexing are theoretically evaluated using the conventional noise theory of an optical receiver followed by an optical preamplifier. Experimental results of bit error rate measurements for 100 Gb/s demultiplexing using three different NOLMs with different intrinsic crosstalk values, defined by signal transmittance in the absence of control pulses, show that the power penalties are in good agreement with the evaluation based upon our proposed analysis. It can be found from our investigation in demultiplexing from 100 to 10 Gb/s that intrinsic crosstalk of less than -25 dB, corresponding to a coupling ratio, K, of |K-0.5|/spl les/0.03, is required for the power penalty of less than 1 dB. The root-mean-square (rms) value of the relative timing jitter necessary for obtaining a sufficient timing tolerance width for combining control and signal pulses is determined.

Ultra-high-speed PLL-type clock recovery circuit based on all-optical gain modulation in traveling-wave laser diode amplifier

A new phase lock loop (PLL) is developed for very-high-speed optical timing extraction using traveling-wave laser-diode amplifier (TW-LDA) as a phase detector. The all-optical gain modulation of the TW-LDA is utilized to detect the relative phase difference between an optical signal and an optical clock The frequency response of the optical gain modulation measured with the optical heterodyne technique agrees with the theoretical results based on a rate equation model. With the developed PLL, 10-GHz optical timing clock is successfully extracted from randomly modulated optical signal pulses and the measured bit-error-rate performance shows no power penalty. Influence of the received optical noise on the phase variance of the PLL is also evaluated and it is concluded that 100 GHz operation is possible by increasing the input optical power to 10 mW. >

100-Gb/s multiple-channel output all-optical OTDM demultiplexing using multichannel four-wave mixing in a semiconductor optical amplifier

We present a successful demonstration of ultra-fast all-optical time-division demultiplexing with simultaneous multiple-channel output, a vital function for all-optical demultiplexers. The demultiplexing operation is based on multichannel four-wave mixing (FWM) in a semiconductor optical amplifier. Error-free, simultaneous live-channel-output, 100-6.3-Gb/s demultiplexing is successfully performed.

3 Tbit/s (160 Gbit/s/spl times/19 ch) OTDM/WDM transmission experiment

3 Tbit/s (160 Gbit/s/spl times/19 channels) optical signal is successfully transmitted over 40 km dispersion-shifted fiber. Low noise supercontinuum signal pulse sources and 70 nm bandwidth tellurite-based optical amplifiers are used for 3 Tbit/s signal generation and amplification.

Low-loss, 2 km-long photonic crystal fiber with zero GVD in the near IR suitable for picosecond pulse propagation at the 800 nm band

Summary form only given. A 2 km-long hexagonal photonic crystal fiber with losses at 1550 and 850 nm of 3.2 and 7.1 dB/km, respectively, was successfully fabricated. The zero GVD wavelength was measured to be 810 nm, and picosecond optical pulses at 815 nm were successfully propagated through the fiber.