Shoichiro Kuwahara

A 40-Gb/s/ch WDM transmission with SPM/XPM suppression through prechirping and dispersion management

This paper proposes to combine prechirping with dispersion management scheme in such a way as to suppress the power penalty induced by self-phase modulation (SPM) and cross-phase modulation (XPM) in 40-Gb/s per channel wavelength-division multiplexed (WDM) transmission systems with long-amplifier spacing. First, we show that the optimum total dispersion to minimize SPM depends on prechirping and the local dispersion of the transmission fiber, unlike that for minimizing XPM. Next, it is shown that, by optimizing the combination of prechirping and local dispersion, these two optima can be made to match so as to improve the allowable maximum fiber input power. Finally, the operation of the proposed optimization scheme is confirmed experimentally, and 4/spl times/40-Gb/s WDM transmission over 400 km of nonzero dispersion-shifted fiber (NZDSF) is demonstrated successfully with the fiber input power of +10 dBm/ch and 250 GHz channel spacing.

1.2 Tbit/s (30/spl times/42.7 Gbit/s ETDM optical channel) WDM transmission over 376 km with 125 km spacing using forward error correction and carrier-suppressed RZ format

We demonstrate 1.2 Tbit/s (30/spl times/42.7 Gbit/s electrical time division multiplexing (ETDM) optical channel) WDM transmission over three 125 km-spans (span loss: 31.5 dB average) using carrier-suppressed return-to-zero format and forward error corrections in 50 nm tellurite-based EDFA gain band.

A novel dispersion compensation scheme based on phase comparison between two SSB signals generated from a spectrally filtered CS-RZ signal

We proposed a novel dispersion compensation scheme based on relative phase detection of two SSB components of CS-RZ transmission code. These two components have NRZ pulse shape. Chromatic dispersion was detected by using 43-Gbit/s comparator HEMT ICs. The proposed technique successfully detected signs of chromatic dispersion and has sensitivity of 0.16-ps/nm/mV. Furthermore, the use of SSB-DD technique enabled us to achieve a wider dispersion tolerance (65-ps/nm) than that of a conventional CS-RZ signal.

Performances of CSRZ-DPSK and RZ-DPSK in 43-Gbit/s/ch DWDM G.652 single-mode-fiber transmission

Numerical simulation showed that a carrier-suppressed return-to-zero DPSK signal has higher spectral efficiency and more tolerance to fiber-nonlinearity-induced impairment compared with an RZ-DPSK signal. A 3-dB enhancement in the maximum allowable fiber-launched power was achieved in G.652 SMF transmission.

First- and higher-order PMD tolerance of carrier-suppressed return-to-zero format with forward error correction

The first- and higher-order PMD (polarization mode dispersion) tolerances of several line-codes with FEC are clarified experimentally. The CS-RZ format with FEC is the most robust line-code; it accepts 60% of DGD/bit-time-interval with the existence of higher-order PMD.

Adaptive dispersion equalization by monitoring relative phase shift between spacing-fixed WDM signals

This paper proposes a novel adaptive dispersion equalization system that equalizes the temperature-induced dispersion fluctuation in long-span ultra-high-speed optical transmission systems. The system monitors the dispersion fluctuation by measuring the relative delay between two wavelength division multiplexed (WDM) signals, and equalizes the dispersion fluctuation by wavelength tuning. A variable-dispersion equalizer can be used instead of wavelength tuning. Adaptive equalization is successfully demonstrated in 40-Gb/s (8-ps-RZ pulses) 400-km transmission. Furthermore, the proposed equalization system is shown to be applicable to WDM systems that use dispersion and dispersion slope compensation. Since the sensitivity to the dispersion fluctuation is improved by extending the wavelength spacing of the signal and monitor channels, the system is shown to operate even when polarization-mode dispersion (PMD) of the transmission fiber must be taken into account.

Reduction of nonlinear crosstalk by carrier-suppressed RZ format for 100 GHz-spaced Nx43-Gbit/s WDM in non-zero dispersion shifted band

We demonstrate that the carrier-suppressed RZ format reduces the nonlinear crosstalk in non-zero dispersion shifted fiber (+1.7 ps/km/nm) compared to the NRZ format in 100 GHz-spaced 8/spl times/43 Gbit/s WDM transmission using terminal dispersion compensation.

Mode-locked lasers for 43 Gb/s carrier-suppressed return-to-zero pulse generation

Optical pulse sources based on mode-locked lasers are reported for 43 Gb/s carrier-suppressed return-to-zero pulse generation. A 150 km dispersion-shifted-fiber L-band transmission is demonstrated using the pulse source.

Ultra-wideband remotely-pumped EDF/DRA hybrid inline-repeater system using tellurite-based EDFs and 1500-nm pumping method

A novel wideband remotely-pumped EDF/DRA hybrid inline-repeater system that offers the widest-to-be-reported 80-nm (1535-1615 nm) seamless gain-band and an OSNR improvement of 1.9 dB is constructed using tellurite-based EDFs and a 1500-nm pumping method.

Adaptive dispersion equalization of 8-ps pulses in 400-km transmission line by monitoring relative phase shift between spacing-fixed WDM signals

We propose an adaptive dispersion equalization system based on wavelength tuning and monitoring the relative phase shift between fixed-spacing wavelength-division multiplexing (WDM) signals. Adaptive equalization is successfully demonstrated for 40-Gbit/s (8-ps RZ pulses) 400-km transmission.