A reconfigurable tri-directional transmission module (TTM) is proposed and experimentally demonstrated in a dense wavelength division multiplexing (DWDM), 2.5 Gb/s x 100 Km lightwave system. Channel spacing is 100 GHz (0.8 nm) in our study. Bit error rate floor of 10<sup>-4</sup> exists due to channel crosstalk and Rayleigh back scattering is observed. Nevertheless, power penalty could be effectively reduced to 0.6 dB by using a tunable bandpass filter. This module may find an important role in the tri-directional lightwave system, especially when wavelengths interchange, optical cross connect and optical add/drop functions are necessary.
Optical Virtual Private Network (OVPN) is an increasingly important application of Automatic Switched Optical Network (ASON). To meet the demands of today's different types of network services, dynamic OVPN technique is studied and two new functions are brought forward, which are dynamic connection management, and fast protection/restoration. We realize dynamic OVPN technique in the first ASON testbed in China, based on GMPLS signaling mechanism. The dynamic OVPN technique makes the optical network able to provide customers with reliable and flexible services by more functional and intelligent methods.
A genetic algorithm is proposed with permutation based chromosome presentation and roulette wheel selection to solve traffic grooming problems in WDM ring network. The parameters of the algorithm are evaluated by calculating of large amount of traffic patterns at different conditions. Four methods were developed to improve the algorithm, which can be used combining with each other. Effects of them on the algorithm are studied via computer simulations. The results show that they can all make the algorithm more powerful to reduce the number of add-drop multiplexers or wavelengths required in a network.
The authors propose a multiwavelength bi-directional optical crossconnect (B-OXC) structure based on 1x16 multiplexer/demultiplexer (MUX/DMUX) and 2x2 optical switches. The 2x2 B-OXC system is implemented using one pair of array waveguide grating (AWG) based MUX/DMUX and all channels can be cross-connect independently in either direction. The bit error rate (BER) performance of the bi-directional WDM add/drop multiplexer is experimentally studied for a data rate of 2.5 Gb/s per channel, providing an overall capacity of 40 Gbit/s (2.5 Gb/s x 16 chs) in a 400 Km transmission. The worst channel crosstalk level is -37 dB and the typical switching time is 10 ms. We found that the performance of the B-OXC signals is only 1.0 dB degraded by a backward propagating signal.
Link management protocol (LMP) is proposed in generalized MPLS in order to manage the links between adjacent nodes. IETF specifies four basic functions in relevant drafts: control channel management, physical connectivity verification of the data links, link property correlation, downstream alarms and link failure localization. In this paper we discuss LMP and bring forward two new functions: link protection and restoration, and service-relational links. The extension makes the optical network more reliable and more flexible to different kinds of services.