Hiroshi Onaka

Fast optical channel recovery in field demonstration of 100-Gbit/s Ethernet over OTN using real-time DSP

A field trial of 100-Gbit/s Ethernet over an optical transport network (OTN) is conducted using a real-time digital coherent signal processor. Error free operation with the Q-margin of 3.2 dB is confirmed at a 100 Gbit/s Ethernet analyzer by concatenating a low-density parity-check code with a OTN framer forward error correction, after 80-ch WDM transmission through 6 spans x 70 km of dispersion shifted fiber without inline-dispersion compensation. Also, the recovery time of 12 msec is observed in an optical route switching experiment, which is achieved through fast chromatic dispersion estimation functionality.

Modulation and demodulation techniques in optical heterodyne PSK transmission systems

Modulation and demodulation techniques are described for an optical PSK heterodyne transmission system operating at 560 Mb/s and 1.2 Gb/s. Performance limitations affecting the receiver sensitivity in a 1.2-Gb/s DPSK system, such as laser phase noise, phase modulation depth, IF center frequency deviation, and local laser power, are studied. High receiver sensitivities for PSK systems were achieved. The applicability of the Mach-Zehnder modulator as a phase modulator for 1.2-Gb/s DPSK is also demonstrated. A 1.2-Gb/s DPSK transmission of over 100 km, using polarization diversity with novel polarization-insensitive automatic frequency control in an attempt to overcome signal fading caused by polarization fluctuation in the transmitting fiber, is also described. A receiver sensitivity of less than -42.8 dBm and varying within 1.4 dB for all states of polarization was achieved. A multichannel high-definition TV (HDTV) transmission experiment using a DPSK polarization-diversity tunable receiver is described. >

FM response of narrow-linewidth, multielectrode lambda /4 shift DFB laser

Flat FM response from 100 kHz to 15 GHz was achieved in a multielectrode distributed-feedback (DFB) laser. A lambda /4-shifted corrugation and a 1200- mu m-long cavity were very effective not only in reducing the linewidth to less than 1 MHz, but also in making FM response flat by selective current injection.<<ETX>>

Measuring the longitudinal distribution of four-wave mixing efficiency in dispersion-shifted fibers

We measured and analysed four-wave mixing (FWM) efficiency and fluctuation along the actual dispersion-shifted fibers (DSFs). In the short, 1.1-km DSF, our results agreed with theory, and we also obtained zero-dispersion wavelength /spl lambda//sub 0/, zero-dispersion slope dD/d/spl lambda/, and nonlinear refractive index n/sub 2/ simultaneously. In the long, 23-km, DSF, a high FWM efficiency was observed in the wide wavelength region, due to the longitudinal zero-dispersion wavelength distribution. The fluctuation range was about 3.5 nm and the maximum slope about 1.1 km/nm.<<ETX>>

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.

WDM Optical Packet Interconnection using Multi-Gate SOA Switch Architecture for Peta-Flops Ultra-High-Performance Computing Systems

We propose a 100-Tbps-class throughput WDM optical packet interconnection for peta-flops ultra-high-performance computing systems using multi-gate SOA broadcast- and-elect switch architecture. The fundamental result of 6.4Tbps throughput (100Gbps x 64port) WDM optical packet interconnection is obtained.

Driver-less 40 Gb/s LiNbO/sub 3/ modulator with sub-1 V drive voltage

We have succeeded in reducing the drive voltage of a 40Gb/s LiNbO/sub 3/ modulator to 0.9 V, which is the lowest-drive-voltage 40Gb/s LiNbO/sub 3/ modulator in the world. The modulator can be driven within the break down voltage of a SiGe transistor. This result was achieved using a new design concept that featured a wide-gap, long CPW (coplanar waveguide) electrode.

Photonic network R&D activities in Japan-current activities and future perspectives

R&D activities on photonic networks in Japan are presented. First, milestones in current ongoing R&D programs supported by Japanese government agencies are introduced, including long-distance and wavelength division multiplexing (WDM) fiber transmission, wavelength routing, optical burst switching (OBS), and control-plane technology for IP backbone networks. Their goal was set to evolve a legacy telecommunications network to IP-over-WDM networks by introducing technologies for WDM and wavelength routing. We then discuss the perspectives of so-called PHASE II R&D programs for photonic networks over the next 5 years until 2010, by focusing on the report that has been recently issued by the Photonic Internet Forum (PIF), a consortium that has major carriers, telecom vendors, and Japanese academics as members. The PHASE II R&D programs should serve to establish a photonic platform to provide abundant bandwidth on demand, at any time on a real-time basis, through the customers initiative to promote bandwidth-rich applications, such as grid computing, real-time digital-cinema streaming, medical and educational applications, and network storage in e-commerce.

BER estimation in optical fiber transmission systems employing all-optical 2R regenerators

A bit error rate estimation method for optical fiber transmission systems employing all-optical 2R regenerators is presented. The method is based on the linearization of the nonlinear transfer function of the regenerators in three sections. Using this linearized three-section model, the impact of 2R regeneration on the system performance as a function of the extinction ratio, the clamping factor, and the steepness of the transfer function is studied.

128/spl times/10.66 Gbit/s transmission over 840 km standard SMF with 140 km optical repeater spacing (30.4 dB loss) employing dual-band distributed Raman amplification

We present the first demonstration of a high-capacity (1.28 Tbit/s), long-haul (6/spl times/140 km) WDM transmission employing dual-band (C/L-band) distributed Raman amplification (DRA). The DRA improved OSNR and enabled an extra-long repeater spacing of 140 km.