Takuya Ohara

Fiber-edge electrooptic/magnetooptic probe for spectral-domain analysis of electromagnetic field

We propose a new class of an electromagnetic-held probing scheme for microwave planar circuit diagnosis. The measurement principle is based on the electrooptic/magnetooptic effects of crystals glued at optical fiber facets. We have combined the concept of those fiber-edge probes with a fiber-optic RF spectrum analyzing system containing a continuous-wave semiconductor laser source, a fast photodetector, and an RF spectrum analyzer to realize a highly sensitive measurement equipment of local impedance. Electromagnetic-field intensity on a microstrip transmission line has been measured in the frequency domain, where voltage and current amplitudes have been independently investigated with sensitivities of 16 mV/Hz-1/2 and 0.33 mA/Hz-1/2, respectively. In addition, it has been shown that the former value can be improved to be 0.7 mV/Hz-1/2 or smaller by the resonant cavity enhancement effect.

Elastic and adaptive optical networks: possible adoption scenarios and future standardization aspects

There is growing recognition that we are rapidly approaching the physical capacity limit of standard optical fiber. It is important to make better use of optical network resources to accommodate the ever-increasing traffic demand. One promising way is to introduce elasticity and adaptation into the optical domain through more flexible spectrum allocation, where the required minimum spectral resources are allocated adaptively based on traffic demand and network conditions. In this article, we discuss elastic and adaptive optical networks from the perspective of future standardization. We first overview the architecture, enabling technologies, and benefits of elastic and adaptive optical networks with the new concept of an optical corridor. We then present possible adoption scenarios from current rigid optical networks to elastic and adaptive optical networks. We discuss some possible study items that are relevant to the future standardization activities. These items include optical transport network architecture, structure and mapping of the optical transport unit, automatically switched optical network/generalized multiprotocol label switching control plane issues, and some physical aspects with possible extension of the current frequency grid.

The operator's view of OTN evolution

This article presents OTN evolution from an operators point of view, including the history of the transport network, the role of the OTN, and the motivations and requirements for OTN evolution. First, a history of transport networks and the role of the OTN in todays networks is reviewed. Next, the motivation for the OTN evolution, operator requirements, and new OTN capabilities are described. Lastly, the future of the OTN is discussed.

Multi-Layer Greenfield Re-Grooming with Wavelength Defragmentation

Flexible network design for multi-granular and quasi-dynamic traffic is important to minimize resource requirements. In the wavelength layer, wavelength blocking must also be reduced to achieve further cost reduction. We propose a novel traffic accommodation scheme based on repetitive Greenfield Re-grooming with Wavelength Defragmentation (GRWD), which is similar to storage-disk defragmentation. Numerical evaluation shows the required minimum number of sets of transport equipment for the proposed scheme.

A high SNR, 150 ch supercontinuum CW optical source with precise 25 GHz spacing for 10 Gbit/s DWDM systems

A 150 channel multi-wavelength CW optical source with precise 25 GHz spacing is successfully realized by longitudinal mode slicing of a supercontinuum spectrum. We confirm the generation of more than 150 CW channels ranging from 1530 to 1560 nm with SNRs over 28.2 dB and Q-factors over 20.8 dB which are sufficient for 10 Gbit/s multi-span DWDM transmission.

Low-Crosstalk 103 Channel

We propose a low-crosstalk multichannel wavelength conversion scheme based on a parametric process. Simultaneous wavelength conversion of 25 GHz spaced 103 channeltimes10 Gb/s (1.03 Tb/s) wavelength-division multiplexing signals with an 8- and 4-nm guard band is successfully demonstrated by using a quasi-phase-matched lithium niobate waveguide. The method is evaluated both theoretically and experimentally

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This paper reports 160-Gb/s optical time-division-multiplexed (OTDM) technologies including an all-optical integrated multiplexer (MUX) providing all-channel independent modulation, an all-optical integrated demultiplexer (DEMUX) that offers all-channel simultaneous demultiplexing, and a drift-free phase-locked-loop (PLL)-type clock recovery circuit for ultrahigh-speed OTDM signals. We present the configuration of each technology and the results of experiments on those technologies. Highly stable operation is successfully demonstrated by using a MUX based on periodically-poled lithium niobate (PPLN) hybrid integrated planer lightwave circuit (PLC), a DEMUX based on semiconductor optical amplifier hybrid integrated PLC, and clock recovery circuit based on a PLL with an optical phase modulator and a PPLN waveguide

10 Gb/s (1.03 Tb/s) Wavelength Conversion With a Quasi-Phase-Matched LiNbO

We study the multi-flow optical transponder from the viewpoint of OTN. Rate flexible OTU and multiplexing hierarchy for the elastic network are studied in detail and the required OTN standard extension is elucidated.

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We propose a multi-layer network with in-service traffic re-grooming. The combination of colorless multi-degree ROADM and ODU cross-connect with ODU reallocation functionality can offer significant cost reduction with no impact of re-grooming on services.

Waveguide

A novel ODU path switching using dynamic delay difference compensation for ODU reallocation without bit disruption is proposed. The proposed bit-loss-free path switching is successfully demonstrated for 10Gbit/s ODU2 path.