Vol.4 No.2 2011

Research paper : Demonstration of optical communication network for ultra high-definition image transmission (J. Kurumida et al.)−111−Synthesiology - English edition Vol.4 No.2 (2011) distribution for the viewer. It was also designed to handle the multiple bitrate signals containing 1 Gb/s, 10 Gb/s, and 43 Gb/s. The software that indicated the reservation status of the optical path was developed, and the user interface was provided at the same time. 4.1.2 Mutual connection to the Optical Packet and Circuit Integrated Network (NICT)To demonstrate that the mutual servicing of heterogeneous network was possible, we conducted the demonstration jointly with the Optical Packet and Circuit Integrated Network of the National Institute of Information and Communication Technology (NICT). With the cooperation of NICT, the hand-over of the control signal was determined and was accomplished by exchanging the contents and service information at the connection node. High-quality service without delay or data loss could be provided through the Optical Packet and Circuit Integrated Network[4]. 4.2 Communication lineWhile it was possible to configure the network without using the optical fibers that were already laid (field fiber), it was necessary to use the field fibers since fiber laying fell outside of our objective (scenario) of the demo experiment. However, renting the commercial optical fiber over long distances increased the cost burden. Therefore, we borrowed the R&D testbed network that is called JGN2plus[5] and incorporated it into the experimental system to obtain the practical communication distance. This allowed us to test the factors of communication instability and limitations that might occur in reality. Considering the geography and the convenience of this test bed, the use of JGN2plus was suitable for this demo experiment. The details will be explained in subchapter 5.1 along with the site of experiment.4.3 Node equipment and devices4.3.1 Silicon photonics switch (AIST)Optical devices that have a capability of the low power consumption and integration in the network are attractive, and AIST is working on the development of the cross bar switchTerm 2 using the silicon photonics technology[6]. This switch was incorporated into the network node for the configuration that enabled the transmission of video data for the first time. Although the general-use PLC optical switch was employed as the switch for some of the communication nodes, this silicon photonics switch was incorporated since low power consumption and highly integrated multiple ports could be demonstrated. 4.3.2 Current-injection-type silicon-based high-speed optical switch (Fujitsu)At the Fujitsu Laboratories, Ltd., the development of the small silicon-based optical switch that allows mixed integration with electrical circuit is being done for the future dynamic optical path network. Fujitsu achieved a high-performance device with extremely high optical confinement efficiency as well as small cross-sectional surface area, employing the nano wire rib waveguide transverse direction p-i-n diode structure. It also achieved the switching speed of ns with the lowest switching power in the world[7]. This switch was also incorporated into the network node for the demo experiment. 4.3.3 Power-saving next-generation ROADM (NEC)The reconfigurable optical add/drop multiplexer (ROADM) is equipment that enables efficient operation of the super high-speed high-capacity optical transmission network, by combining the wavelength multiplexing method and path control. Currently, there is insufficient degree of freedom in the optical path setting in the node devices of the network in which ROADM is deployed. The equipment system that allows switching the transponderTerm 3 stored in the node at arbitrary wavelength and direction is important. NEC Corporation developed the transponder aggregatorTerm 4 to increase the freedom of optical path setting, and this will ultimately improve the use efficiency of the transponder[8]. 4.3.4 High-speed wavelength tunable laser (Trimatiz)Since it is necessary to be able to dynamically switch the wavelength in the future optical networks, the achievement of high speed in wavelength switching will be the key. Trimatiz, Ltd. is developing the wavelength tunable light source device based on the wavelength tunable laser diode (T-LD) that allows switching of the wavelength at millisecond or less. This technology allows the single T-LD to be tuned stably at high speed and a device that allows 5 GHz resolution tuning of the C-bandTerm 5 was achieved. This was installed in the input end of the NEC’s ROADM equipment, to create a configuration that allowed the switching of the wavelength. 4.3.5 Optical amplifierThe optical amplifier (Erbium-doped fiber amplifier: EDFATerm 6) must be used to compensate the loss of the optical fiber communication line. The key point is to determine where in the network this device should be placed and the position is determined by the loss information on the optical fiber corresponding to the distance. In the optical path network, since the wavelength is switched dynamically, the EDFA must be capable of following the transient response[9], and therefore, we selected the amplifier which has a suppressing technology of the transient response. 4.3.6 Parametric arbitrary wavelength converter (Furukawa Electric and AIST)The wavelength converting technology is essential to effectively utilize the wavelength resource in the future optical path network. Since the coherent wavelength conversion using the highly nonlinear fiber (HNLF) can maintain the state of the light phase after conversion, in principle, it is not dependent on the data modulation format or modulation speed[10]. Other than HNLF, there is the semiconductor


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