Takafumi Terahara

Compensation of pulse shape distortion due to chromatic dispersion and Kerr effect by optical phase conjugation

Pulse shape distortion due to chromatic dispersion and self-phase modulation in a single-mode fiber was effectively compensated for by using an optical phase-conjugate wave generated by nondegenerate forward four-wave mixing in a zero-dispersion single-mode fiber. Using optical phase conjugation at the midpoint of a 100-km standard single-mode fiber compensates for the distortion of 10-Gb/s intensity-modulated NRZ pulse at an input power level exceeding +10 dBm with a resultant power penalty of less than 1.2 dB.<<ETX>>

40-Gb/s WDM transmission with virtually imaged phased array (VIPA) variable dispersion compensators

We have demonstrated variable dispersion compensation by using a virtually imaged phased array (VIPA) to overcome the small dispersion tolerance in 40-Gb/s dense wavelength-division multiplexing (WDM) transmission systems. By utilizing the periodical characteristics of VIPA compensators, we performed simultaneous dispersion compensation in a 1.28-Tb/s (40-Gb/s/spl times/32 ch; C band) short-haul transmission and confirmed that only two VIPA compensators and one fixed dispersion-compensating fiber are required for a large transmission range of 80 km. This performance can greatly reduce the cost, size, and number of compensator menus in a 40-Gb/s WDM short-haul transmission system. In addition, we achieved 3.5-Tb/s (43-Gb/s/spl times/88 ch; C and L bands) transmission over a 600-km nonzero dispersion-shifted fiber by using VIPA compensators. Although channel-by-channel dispersion compensation is required due to the larger residual dispersion slope in long-haul transmission, the periodical characteristics of the VIPA compensators offer the advantage of considerably reducing the number of different modules required to cover the whole C (or L) band. An adequate optical signal-to-noise ratio, which was the same for all channels, was-obtained by using distributed Raman amplification, a gain equalizer, and a preemphasis technique. We achieved a Q-factor of more than 11.8 dB; (BER<10/sup -17/ with forward-error correction) for all 88 channels.

Comparison of span configurations of Raman-amplified dispersion-managed fibers

We evaluate the performance of dispersion-managed fiber transmission systems employing distributed Raman amplification with 50- and 100-km span length for three different span configurations. The evaluation considers the optical signal-to-noise ratio and the nonlinear phase shift as a measure for the impact of nonlinear effects. The simulation results indicate that a 100-km-long span with the dispersion compensating fiber placed in the span center achieves the best tradeoff between optical signal-to-noise degradation and nonlinear effects.

Hybrid Link/Path-Based Design for Translucent Photonic Network Dimensioning

The advancement of ultralong-haul transmission technology has dramatically enhanced the all-optical reaches. However, the actual situations of installed fiber and sites for terrestrial network often prevent implementing a purely transparent network, and thus, opaque reshaping retiming regenerating (3R) regeneration is required to guarantee optical signal reachability. Since 3R regenerators based on optical/electrical/optical conversion tend to dominate the total network costs, an efficient network design method that allocates a minimum number of 3R regenerators to optimum locations is essential to build a cost-effective photonic network. In this paper, we propose such a network-dimensioning method by combining the advantages of link-based and path-based design approaches. It first guarantees optical signal reachability for any possible traffic demand in each segmented linear link. After combining all the links, excessive regenerators are eliminated based on the optical signal quality check with -factor calculation for each wavelength path. A trial design of a large-scale mesh network demonstrated a significant cost savings of more than 30% in comparison with a conventional link-based design. In the trial, the impact of fiber loss coefficient over the total network cost was investigated quantitatively, addressing the importance of such quantitative modeling and analysis.

128-Gbit/s WDM transmission of 24 5.3-Gbit/s RZ signals over 7828 km using gain equalization to compensate for asymmetry in EDFA gain characteristics

Erbium-doped fiber amplifiers (EDFAs) with broad signal bandwidth, low NF and high output power, and transmission characteristic improvement using chromatic dispersion management and modulation format are required for long-haul, wavelength-division multiplexing (WDM) transmission systems. We performed a 24 5.3-Gbit/s WDM transmission experiment over 7828 km using gain equalization to compensate for the asymmetry of the EDFA gain characteristics, RZ modulation format, and both pre- and post-compensation of chromatic dispersion.

Active Gain Slope Compensation in Large-Capacity, Long-Haul WDM Transmission System

Large-capacity, long-haul wavelength-division-multiplexing (WDM) transm1ss1on systems require broad WDM signal bandwidth, which can be expanded with broadband erbium-doped fiber amplifier (EDFA),1 gain-equalizer (GEQ),2,3 and pre-emphasis at the transmitter.

Performance prediction method for distributed Raman amplification in installed fiber systems based on OTDR data

Novel characterization method of the loss profiles in transmission paths for distributed Raman amplification is proposed, which accurately predicts the gain and noise figure from conventional optical time domain reflectometry data.

20-nm signal bandwidth after 147-amplifier chain using long-period gain-equalizers

Summary form only given. Long-haul, large-capacity wavelength-division multiplexing (WDM) transmission systems require broad WDM signal bandwidth, which can be expanded with broadband erbium-doped fiber amplifiers (EDFAs), gain-equalizers (GEQs), and pre-emphasis of optical senders. Twenty-four WDM signals transmission over 2526 km with a 18.4-nm bandwidth and 16 WDM signals transmission over 6000 km with a 12-nm bandwidth have been reported. In this paper, we demonstrate a 20-nm WDM signal bandwidth after 147-amplifier chain (5958-km transmission) using high alumina co-doped EDFAs and long-period gain-equalizers (GEQs). The main GEQs have free-spectral-ranges (FSRs) of 48 nm, which are about two times as long as the wavelength difference between a 1558-nm EDFA gain peak and a 1536-nm EDFA gain valley.

A Quarter Tb/s WDM Transmission Experiments over 2,526 km of Twenty-four, 10.664-Gb/s Data Channels using RZ Modulation Format

0. 256 Tb/s WDM signals were successfully transmitted over 2,526 km. WDM bandwidth of 18.4 nm was achieved using high alumina co-doped EDFAs and gain-equalizers. RZ modulation improved Q-factors by 2 dB.