Experimental studies of optical cross-connect nodes with the centralized management of wavelength and timing clock

超高容量骨干网的使能技术分为两类；网络节点大容量传输技术和光交换技术。其中，波分复用（WDM）技术的最新进展使传输容量达到了兆位/秒的巨大增长。另一方面，为了实现超高容量网络节点，人们提出了各种全光交叉连接（OXC）交换机架构，但它们在实际应用中存在关键问题；例如，所需的光学硬件随着OXC节点的大小而急剧增加，传输信号的质量在OXC中很容易受到损害，等等。本研究的目的是开发光网络节点的技术平台，以应对上述困难，并进行实验验证。在该架构中，网络节点只使用一个多波长脉冲源，并由所有光通道共享。在这种配置中，我们可以通过一个光源管理信号波长和定时时钟来减少光学硬件。这也导致了波长数量的可扩展性。本文的研究结果总结如下：(1)利用光纤中的超连续谱产生技术，研制了超低时序抖动的多波长脉冲源。(2)研究了光电振荡器（OEO）对光脉冲的时序提取，实现了小于100 fs的低时序抖动光时钟源的同步。(3)开发了可重构光网络的在线监控技术，并在实际WDM传输系统中进行了在线色散监控的演示。(4)在此基础上开发了一种波长选择性的OXC开关，并实现了OXC操作，实现了波长数量的可扩展性。少

Enabling technologies for ultra-high capacity backbone networks are divided into two categories ; high-capacity transmission technology and optical switching technology at network nodes. Among them, the recent progress in the wavelength-division multiplexing (WDM) technique have achieved the tremendous growth of the transmission capacity up to tera-bit/sec. On the other hand, in order to realize the ultra-high capacity network nodes various architectures of all-optical cross-connect (OXC) switches have been proposed, but they have crucial issues for practical use ; for example, the required optical hardware increases drastically with the size of the OXC node, the quality of the transmission signal can easily impaired in the OXC, and so on.The aim of this study is to develop the technology platform of optical network nodes which can cope with the aforementioned difficulties and to demonstrate it experimentally. In the proposed architecture, only a multi-wavelength pulse source is used i … More n the network node and shared with all optical channels. In this configuration, we can reduce the optical hardware by managing the signal wavelength and the timing clock by one light source. This also leads to the scalability for the number of wavelengths.The results of this studies are summarized as follows ; (1) we developed the multi-wavelength pulse source with the extremely low timing jitter by using the super-continuum generation technique in optical fibers. (2) we investigated the timing extraction of optical pulses by the opto-electric oscillators (OEO), and realized the synchronization of optical clock sources with low timing jitter lower than 100-fs. (3) we developed the in-service monitoring technique for the reconfigurable optical network, and demonstrate the in-service dispersion monitor in actual WDM transmission systems. (4) we developed an wavelength-selective OXC switch based on the proposed architecture and realized the OXC operation which can realize the scalability for the number of wavelength. Less