Investigation on performance of all optical buffer with large dynamical delay time based on cascaded double loop optical buffers

Optical buffers are critical for optical signal processing in future optical packet-switched networks. In this paper, a theoretical study as well as an experimental demonstration on a new optical buffer with large dynamical delay time is carried out based on cascaded double loop optical buffers （I：）LOBs）. It is found that pulse distortion can be restrained by a negative optical control mode when the optical packet is in the loop. Noise analysis indicates that it is feasible to realise a large variable delay range by cascaded DLOBs. These conclusions are validated by the experiment system with 4-stage cascaded DLOBs. Both the theoretical simulations and the experimental results indicate that a large delay range of 1-9999 times the basic delay unit and a fine granularity of 25 ns can be achieved by the cascaded DLOBs. The performance of the cascaded DLOBs is suitable for the all optical networks.

An Improved MAC Scheme of HORNET Based on Node Structure with Variable Optical Buffer

An improved unslotted CSMA/CA MAC scheme of HORNET based on the node structure with variable optical buffer is reported. It can be used for transmitting high effectively all variable IP packets in the WDM network.

Low dispersion broadband integrated double-slot microring resonators optical buffer

Microring resonator optical buffer is attractive in high-speed optical network system, but ordinary microring resonator use strip waveguide as its basic light guide medium, which cannot provide small footprint, low dispersion and high delay-bandwidth product （DBP） simultaneously. Double-slot waveguide structure was first proposed to construct racetrack-microring resonators. It was found that cascading multiple microrings can increase the delay-bandwidth and lower the dispersion of the resonators by optimizing the structure parameters. Optical buffer cascaded by 8 microrings with fiat bandwidth of 20 GHz provided the delay of 150 ps and the dispersion of -10-7 ps/um over 1530-1630 nm, and the footprint of each microring was about 511ma2. This study can provide design methods and theoretical basis support for practical application.

Ultra-Short Pulse Tracking by Using Wavelength Dispersion for a Short-Time Optical Buffer

To synchronize a control signal with a packet signal in response to changing timing jitter, we investigate ultra-short pulse tracking by using wavelength dispersion for a short-time optical buffer in an optical router.

Study of Crosstalk Property in an Optical Packet Switching Node

The effect of queuing delay of output buffer on the crosstalk property in optical packet switching nodes is investigated. The relationship between crosstalk and buffer length is obtained. From the calculation and simulation results, it is concluded that the crosstalk power penalty predominantly depends on the buffer length, the longer the buffer, the greater the penalty, as well as the random range of the penalty. While comparing with the effect of queuing delay, the effect of random routing path delay takes very little proportion in the total power penalty.

Simulation of the Physical Performance of Optical Packet Switching Nodes

A graphical and visual simulation system for the study of optical packet switching (OPS) nodes is accomplished. With the simulation system, the effect on physical performance-bit error rate (BER) due to a variety of factors such as the crosstalk parameters of OPS nodes, number of cascaded OPS nodes, length of optical output buffer, traffic load and fluctuation of amplitude of optical signals are evaluated. Reliability of the simulation system is proved by the analytical results obtained in all the above cases.

All optical wavelength converter and its application in optical network

All optical network （AON） is a hot topic in recent studies of optical fiber communications. Key techniques in AON include optical switching/routing, optical cross connection （OXC）, all optical wavelength conversion （AOWC）, all optical buffering, etc. Opti- cal switching/routing is in fact wavelength switching/ routing. OXC and wavelength conversion （WC） are introduced into cross nodes so that a virtual wavelength path is established. With WC, communication route is formed only if there is unused wavelength in an individual segment link. The rate wavelength usage is thus greatly increased. The blocking rate of network can be reduced by adding WCs, especially for huge capacity multiple nodes ones. Therefore, WC has attracted much attention in basic research of optical communication and is used in some experimental networks.This dissertation studies all optic wavelength conversion and its application, with the contributions in the following five aspects.

Dispersion of double-slot in optical microring resonators buffer

In the optical packet switching network, optical buffer is an important device. Microring resonator optical buffers provide good delay performance and flexibility in design. By cascading multiple microring resonators, higher delay-bandwidth product is obtained, but the requirements of high integration and low dispersion are hard to satisfy simultaneously. Double-slot waveguide was proposed to construct highly integrated racetrack microring resonators in this study. Based on dispersion analysis of the thickness of each layer of a waveguide, the structure ofwaveguide was optimized to reach flat and low dispersion. Average dispersions of straight and 3 μm bend waveguides were 5.1 ps/（nm·km） and 4.4 ps/（nm· km）, respectively. Besides, the additional loss from coupling was greatly reduced when applying proper relative displacement between straight and bend waveguides. Theoretical and design basis provided in this paper will help to develop multi-microring optical buffers in the future.