Kazushige Yonenaga

Dispersion-tolerant optical transmission system using duobinary transmitter and binary receiver

We propose a dispersion-tolerant optical duobinary transmission system which uses a binary intensity modulation direct detection (IM-DD) receiver. The proposed system also relaxes the fiber input power limitation due to stimulated Brillouin scattering (SBS). Tolerance to chromatic dispersion in the proposed system is estimated by a simulation. A 10 Gb/s optical duobinary signal can be transmitted over 200 km of standard single-mode fiber (SMF) with 1 dB dispersion penalty. The advantages of the proposed system are confirmed experimentally. The optical duobinary signal was successfully received by the binary IM-DD receiver at the same sensitivity as a binary IM signal. Power penalty due to chromatic dispersion over a 164-km standard SMF was about 1.8 dB at 10 Gb/s. The SBS threshold of the 10 Gb/s optical duobinary modulated light was more than +20 dBm.

Multiflow optical transponder for efficient multilayer optical networking

Growing concerns regarding the scalability of current optical networks as well as IP-based networks are driving two important trends. One trend is a shift from the current rigid optical networks to spectrally efficient elastic optical networks with a flexible bandwidth and adaptive channel spacing. The other trend is IP traffic offloading to a lower layer yielding benefits that are potentially cost-effective and power-efficient. This article presents a novel multiflow optical transponder (OTP) that enables more efficient IP optical networking. A multiflow OTP allows client data flows that arrive from a single client interface to be mapped to multiple optical flows. In cooperation with the emerging spectrally efficient elastic optical path networking technology, multiflow OTPs can provide multiple optical connections from a single OTP to multiple OTPs. IP traffic offloading to an elastic optical path layer architecture and the effect of introducing multiflow OTPs (i.e., the potential reduction in the number of router interfaces and considerable potential for cost savings) are discussed. These benefits are brought about by increasing the number of directly connected router pairs while keeping router-to-optical-node interconnections simple. A novel optical virtual private line service based on multiflow OTPs that supports multiple optical connections from a single customer site to multiple customer sites with capacity adjustment is also discussed.

Demonstration of novel spectrum-efficient elastic optical path network with per-channel variable capacity of 40 Gb/s to over 400 Gb/s

We demonstrated, for the first time, a novel spectrum-efficient elastic optical path network for 100 Gb/s services and beyond, based on flexible rate transceivers and variable-bandwidth wavelength crossconnects.

640-Gbit/s optical TDM transmission over 92 km through a dispersion-managed fiber consisting of single-mode fiber and "reverse dispersion fiber"

A 640-Gbit/s optical time division multiplexed signal was successfully transmitted over a 92-km zero-dispersion-flattened transmission line. The transmission line consisted of single-mode fiber, dispersion-shifted fiber, and reverse dispersion fiber. By using reverse dispersion fiber instead of dispersion slope compensation fiber, we were able to increase the transmission distance from 63 to 92 km because reverse dispersion fiber has less polarization mode dispersion and a flatter dispersion profile.

A fiber chromatic dispersion compensation technique with an optical SSB transmission in optical homodyne detection systems

A fiber chromatic dispersion compensation technique with optical single-sideband (SSB) transmission in optical homodyne detection systems is described. The chromatic dispersion compensation technique is demonstrated in a 6-Gb/s SSB phase-shift-keying (PSK) homodyne detection system equivalent experiment. A 270-km conventional single-mode fiber is used as a transmission medium at 1.55 mu m, and a microstrip line is used as a delay equalizer. The effect of compensating for the chromatic dispersion with the microstrip line is verified by improvement of eye-opening.<<ETX>>

Compensation of Interchannel Crosstalk Induced by Optical Fiber Nonlinearity in Carrier Phase-Locked WDM System

A scheme that compensates the waveform distortion induced by nonlinear interchannel crosstalk such as four-wave mixing (FWM) and cross-phase modulation as well as self-phase modulation in phase-locked wavelength-division-multiplexing transmission systems is proposed. Reduction of FWM-induced waveform distortion by controlling the phase relationship between neighbouring channels and its cancellation by precompensation is successfully demonstrated

Filtering characteristics of highly-spectrum efficient spectrum-sliced elastic optical path (SLICE) network

We investigate the performance of OFDM-modulated signals in spectrum-sliced elastic optical path network. We analyze the filtering characteristics and the guard band for multi-node transmission. The architecture increases spectral efficiency over the current WDM systems.

Distance-adaptive super-wavelength routing in elastic optical path network (SLICE) with optical OFDM

We propose a spectrally-efficient super-wavelength-path routing in SLICE by selecting a set of subcarrier numbers and modulation levels according to path distances. We demonstrate 420 Gb/s path routing using short-reach 14-subcarrier 8-APSK and long-reach 21-subcarrier QPSK.

40-Gbit/s TDM transmission technologies based on ultra-high-speed ICs

This paper presents 40-Gbit/s time division multiplexing (TDM) transmission technologies based on 0.1-/spl mu/m-gate-length InP high electron mobility transistor ICs and a scheme for upgrading toward a terabit-per-second capacity system. A 40-Gbit/s, 300-km, in-line transmission experiment and a dispersion-tolerant 40-Gbit/s duobinary transmission experiment are described as 40-Gbit/s single carrier system applications on dispersion-shifted fiber. An ultra-high-speed receiver configuration using a high-output-power photodiode is introduced to realize fully electrical receiver operation beyond 40 Gbit/s. The high-sensitivity operation of the optical receiver (-27.6 dBm@BER=10/sup -9/) is demonstrated at a data bit rate of 50 Gbit/s for the first time using a unitraveling carrier photodiode. A dense wavelength division multiplexing (DWDM) system operating up to terabits per second can be easily realized on a zero-dispersion flattened transmission line using ultra-high speed TDM channels of 40 Gbit/s and beyond. An experiment demonstrates 1.04-Tbit/s DWDM transmission based on 40-Gbit/s TDM channels with high optical spectrum density (0.4 bit/s/Hz) without dispersion compensation.

Virtualization in optical networks from network level to hardware level [invited]

Elastic optical networking is attracting much attention as a promising solution to achieve spectrum-efficient transport of higher data rates at 100 Gbits/s and beyond. If we draw an analogy to virtualization in cloud computing, it can be seen as network level resource virtualization of optical networks where spectrum resources in optical links are segmented as shareable resources and adaptively aggregated to create a wide variety of optical channels (OChs). In this paper, we discuss the benefits of introducing virtualization into the optical domain from the viewpoints of the network level and the hardware level. In elastic optical networks, a frequency slot through which an OCh is transported and the OCh itself are explicitly decoupled. While the adaptability in the frequency slot is brought about by bandwidth variable wavelength-selective switches, the adaptability in an OCh is yielded by digital coherent technology that is employed in transponders and regenerators. It is emphasized that in order to achieve transponders and regenerators that accommodate heterogeneous traffic demands in an economical manner, simply being adaptive is not enough, and being shareable is essential. We refer to this concept as hardware level virtualization. As examples, we describe a multiflow transponder and an elastic regenerator with results that show proof of concept. Based on the hardware virtualization concept, we propose an elastic optical transport system (EOTS) architecture that enables cost- and energy-efficient IP traffic offloading to the optical domain and improves programmability and automation of optical networks.