It is essential to extend the optical buffer depth to meet the burst-mode packet requirement. In this paper, we
propose to incorporate the Mach-Zehnder interferometer (MZI) into our successful SOA-based dual loop optical
buffer (DLOB) configuration. The maximum packet length for the DLOB storage is evaluated theoretically, and the
fiber loop utilization can be greatly enhanced with our modified configuration. Then we have successfully
demonstrated the 2.5 Gbps variable-length packet loadable function with the MZI-DLOB configuration. The
waveform of variable-length packet is little degraded after optical storage. Meanwhile an effective polarization
stable method is also experimentally implemented to reduce the instability of MZI-DLOB. All the obtained results
confirm the feasibility of our configuration to apply in variable-length optical packet switching.
A precise measurement method for linewidth enhancement factor of SOA by Sagnac interferometer when considering XGM is presented. It needs neither spacial interference nor optical spectrum analysis, has simple configuration and better measurement stability than existing methods.
The survivability is one of the important issues in Resilient Packet Ring (RPR) networks. This article analyzes a new failure scenario and put forward a new restoration mechanism named as C-steering. The mathematical model has been established to investigate the survivability of the RPR network in three operation methods. The throughput-delay performance and link utilization are discussed theoretically and experimentally.
This paper reports the progress of the 863 high-technology project of China "Optical Resilient Packet Ring (O-RPR) Based on All-optical Buffering Techniques". In this ring network, for the packet through an intermediate node the conversion of O/E/O is not needed in order to overcome the bottleneck of O/E/O. In all-optical node a Dual Loop Optical Buffer (DLOB) is used to revolve the collision between the packet, which pass through the node, and add packet from local user to ring. The principle of DLOB is introduced. The bit-rate of head of optical frame is lower than the bit-rate of payload in a packet, in order to increase the efficiency of transmission link. This paper will introduce the network topology, layers and the structure of optical node. It includes an optical splitter, optical delay line as input buffer, a SOA as optical switch, which switch the packet dropping down form the ring or pass through the node, a DLOB and an electric buffer. An ARM is used for regulation of different buffers. The experiment results of a demonstrate network including 3 nodes are given.
This paper analyzes the performance of DLOB and discusses the influence of SOA's linewidth enhancement factor and XGM on the performance of DLOB, gets the relation between linewidth enhancement factor and extinction ratio, transfer ratio. Then discusses the influence of state of polarization (SOP) on buffer's output power and finds their evolution regularity. Many useful conclusions are drawn.
This paper firstly introduces the principle of distributed sensing system based on Polarization sensitive Optical Time-Domain Reflectometer (P-OTDR). As known, the change of State of Polarization (SOP) in fiber is sensitive to environment, consequently this sensing method can extract very little perturbation of extra temperature or strain; another significant advantage is that the sensing information can be achieved nondestructively at one end. Hence, this technique has become a practical and helpful tool in distributed optical fiber sensing system. However backscattered light in single-mode fiber is very weak, and the optical pulse width limits the spatial resolution, so there is a compromise between SNR and sensor spatial resolution. We investigate two signal-process methods to extract the state polarization (SOP) evolution from backscatted signal. From the experiment results, we find that both the digital average and deconvolution can be used for enhancing SNR and system spatial resolution. And we also find hundred of digital average is enough, the more time we average the less improvement of SNR we get. At the same time, we view that the SOP of backscattered signal is the response of sensing system. By mean of deconvolution the actual SOP evolution is not lost, and the spatial resolution of POTDR System doesn’t degrade with a wider pulse. Compared with previous deconvolution case, the deconvolution method can effectively improve the system spatial resolution without decreasing the transmitting pulse width. Finally we give some experiment results with strain perturbation, our system can detect the point where the environment changes, which is suitable for smart structure and optic-fiber sensor application.
All-optical switch is a key component for all-optical communication and switching; we demonstrate an all-optical switch with two switched output-ports like a nonlinear optical loop mirror (NOLM)based on a 3x3 collinear fiber coupler. After introducing the principle in this paper we give some pulse switching experimental results. In order to avoid high power laser system and save the cost the NOLM loop is made up of 12km G.652 fiber, the extinction ratio of switching signal is more than 20dB. Further we optimize the loop and EDFA, without reducing the extinction ratio we observe the pulse switching in a loop length less than 6km G.652 fiber. Compared to conventional optical switches, this type switch can support two switched output-ports which act complementarily at the same time, this character is practical for optical switching, and data signal can be selected to one of the multi-output ports by optical control signal.