Investigation of the regenerative and cascadability properties of optical signal processing devices at high bit-rates.

This thesis investigates the use of Semiconductor Optical Amplifiers (SOA) for 10 and 40Gb/s all-optical 3R signal regeneration and wavelength conversion for application to advanced high-speed all-optical WDM networks. Detailed experimental characterisation of the magnitude and the time scales of inter-band nonlinear effects in SOA is carried out. The regenerative properties of SOA gates are theoretically investigated and related to the SOA physical parameters by means of deriving the SOA gate transfer function. A novel configuration for all-optical regeneration based on Polarisation Switching in an SOA-assisted Sagnac Interferometer (PSSI) is proposed and used to demonstrate, for the first time, multi-channel simultaneous 3R regeneration. This scheme allows to significantly enhance the switching frequency of the SOA, demonstrating error-free regeneration of 40Gb/s signal with long PRBS sequences using an SOA with carrier lifetime exceeding 250ps. The reshaping and retiming ability of the scheme are also assessed experimentally at bit-rate of 40Gb/s, to show the largest distortion tolerance range published to date for regeneration. The scheme is also used to demonstrate 40 to lOGb/s demultiplexing. The cascadability of optical regenerators and wavelength converters is also investigated experimentally. The impact of varying the inter-regenerator spacing in transmission with cascaded wavelength conversion and 3R regeneration over transoceanic distances, is experimentally investigated for the first time, using a novel reconfigurable fibre loop. These results show that a trade-off exists between the transmission signal Q-factor and the inter-regenerator spacing, which depends on the regenerator transfer function characteristics, and thus can be predicted from the SOA parameters. In 40Gb/s transmission with optical regeneration it was demonstrated that the use of an optical regenerator before the electrical receiver increases the power margin and maximum error-free transmission distance at 40Gb/s in excess of 100km. Finally a novel concept for multi-channel wavelength conversion and regeneration is presented utilising an integrated SOA array in a novel configuration to demonstrate, for the first time, simultaneous regenerative wavelength conversion of 1 OGb/s signals. This also shows the potential for large scale monolithic integration for optical processing applications in WDM networks

Simultaneous all-optical processing of wavelength division multiplexing channels

In this thesis, the possibility of simultaneous all-optical regeneration of wavelength-division multiplexed (WDM) signals within the same optical device is investigated. The optical regeneration scheme discussed in this thesis relies on the exploitation of the SPM induced by the optical Kerr nonlinearity within an optical fibre. In the work presented in this thesis, I report the extension of a particular single-channel all-optical 2R regenerator suitable for on-off keying return-to-zero modulation format to WDM operation. The device is referred to as the Mamyshev regenerator, and provides both Re-amplification and Re-shaping capabilities for the incoming optical signal. An in-depth analysis of the single-channel device reveals that remarkable and simple scaling rules can be established to relate the output properties of the optical regenerate to the characteristics of the incoming signal to be regenerated and key physical parameters defining the optical regenerator. The analysis allows general conclusions to be drawn on the mitigation strategies to be implemented to extend the scheme to the multi-channel case. The extension to the multi-channel scenario is then examined. Minimization of the interaction time between adjacent channels is introduced by inducing a sufficient walkoff between co-propagating signals. The strength of the inter-channel nonlinearities can be sufficiently reduced to preserve the optical regeneration capabilities. Two techniques are therefore reported. One is based on the counter-propagation of two optical signals within the same piece of nonlinear fibre. The second relies on polarization multiplexing of two co-propagating signals. Theoretical aspects and experimental demonstrations at 10 Gb/s, 40 Gb/s, and 130 Gb/s are reporte

SOA - NOLM in Reflective Configuration for Optical Regeneration in High Bit Rate Transmission Systems

This paper presents a theoretical and experimental investigation of optical signal regeneration properties of a non-linear optical loop mirror using a semiconductor optical amplifier as the active element (SOA-NOLM). While this device has been extensively studied for optical time division demultiplexing (OTDM) and wavelength conversion applications, our proposed approach, based on a reflective configuration, has not yet been investigated, particularly in the light of signal regeneration. The impact on the transfer function shape of different parameters, like SOA position in the interferometer and SOA input optical powers, are numerically studied to appreciate the regenerative capabilities of the device.Regenerative performances in association with a dual stage of SOA to create a 3R regenerator which preserves the data polarity and the wavelength are experimentally assessed. Thanks to this complete regenerative function, a 100.000 km error free transmission has experimentally been achieved at 10 Gb/s in a recirculating loop. The evolution of Bit Error Rate for multiple pass into the regenerator and the polarization insensitivity demonstration to input data are presented

An Optical Grooming Switch for High-Speed Traffic Aggregation in Time, Space and Wavelength

In this book a novel optical switch is designed, developed, and tested. The switch integrates optical switching, transparent traffic aggregation/grooming, and optical regener-ation. Innovative switch subsystems are developed that enable these functionalities, including all-optical OTDM-to-WDM converters. High capacity ring interconnection between metro-core rings, carrying 130 Gbit/s OTDM traffic, and metro-access rings carring 43 Gbit/s WDM traffic is experimentally demonstrated. The developed switch features flexibility in bandwidth provisioning, scalability to higher traffic volumes, and backward compatibility with existing network implementations in a future-proof way

Study On All-Optical Signal Processing by Semiconductor Optical Amplifiers for Ultra-High-Speed Optical Fiber Communications

制度:新 ; 報告番号:乙2307号 ; 学位の種類:博士(工学) ; 授与年月日:2011/2/25 ; 早大学位記番号:新564

Practical aspects of fiber optical parametric amplifiers for optical communication

Invited PaperFiber optical parametric amplifiers (OPAs) are based on the third-order nonlinear susceptibility of glass fibers. If two strong pumps and a weak signal are fed into a fiber, an idler is generated. Signal and idler can grow together if pump power is high enough, and phase matching occurs. Until recently, impressive performance of fiber OPAs has been demonstrated in different respects. However, secondary effects should be addressed before OPAs can be utilized in practical applications. Here we report some of these effects, either exploiting them as in the parametric processor such as optical logic gates, inverted and non-inverted wavelength converter, and ultra-wideband monocycle and doublet pulses generator, or suppressing them as in the optical amplifier for WDM systems.published_or_final_versionThe 9th International Conference on Optical Communications and Networks (ICOCN 2010), Nanjing, China, 24-27 October 2010. In Proceedings of the 9th ICOCN, 2010, p. 299-30