Simultaneous chromatic dispersion, polarization-mode-dispersion and OSNR monitoring at 40Gbit/s

A novel method for independent and simultaneous monitoring of chromatic dispersion ( CD), first-order PMD and OSNR in 40Gbit/s systems is proposed and demonstrated. This is performed using in-band tone monitoring of 5GHz, optically down-converted to a low intermediate-frequency (IF) of 10kHz. The measurement provides a large monitoring range with good accuracies for CD (4742 +/- 100ps/nm), differential group delay (DGD) (200 +/- 4ps) and OSNR (23 +/- 1dB), independently of the bit-rate. In addition, the use of electro-absorption modulators (EAM) for the simultaneous down-conversion of all channels and the use of low-speed detectors makes it cost effective for multi-channel operation. (C) 2008 Optical Society of Americ

Stimulated Brillouin scattering in single mode optical fibre ring resonators

This thesis describes the theoretical and experimental investigation of stimulated Brillouin scattering (SBS) in single mode optical fibres and all-fibre ring resonators. SBS is a nonlinear threshold effect which occurs in single mode fibres at low optical pump powers, and can be a limitation in optical fibre coherent transmission systems. High finesse optical fibre ring resonators are attractive for the study of SBS as their geometry offers a very low round-trip loss coupled with a significant enhancement of the circulating power over the input power resulting in low SBS thresholds. After a review of the SBS theory and an overview of the research work carried out in the field of SBS in single mode optical fibres, the system of coupled equations which described the generation of the SBS process is solved numerically. The numerical results are compared with existing analytical solutions and published experimental data, and the implications and applications of the results to optical fibre transmission systems and Brillouin amplifiers are discussed. The evaluation of high finesse single-mode ring resonator operation carried out, including the fabrication, alignment, and characterisation of devices fabricated from ordinary and polarisation maintaining fibre, at 633 nm and 830 nm is described. The theoretical and experimental investigation of SBS generation in all-fibre single mode ring resonators is presented. An analytical theory describing the operation and performance parameters of all-fibre Brillouin lasers is derived, and a numerical modelling of the transient operation of the Brillouin laser is carried out. The transient and steady-state characteristics of a Brillouin amplifier based on an all-fibre ring resonator are considered. The experimental investigation of the operation of all-fibre Brillouin lasers is described. Particular attention focuses on the semiconductor laser pumped Brillouin laser and the first demonstration of this device operating at a submilliwatt threshold is presented. The processes of four wave mixing (FWM) and a related process of Brillouin enhanced four wave mixing (BEFWM) are observed for the first time in all-fibre ring resonators, and the physics of these processes is considered. The applications of the work in this thesis including local oscillators, generation and distribution of high frequency microwave components, amplification, and phase conjugation are also discussed

Candidate technologies for high-capacity optical communication systems

The practicalities in designing high-capacity optical communication systems are described. With a given perspective on the present and future technologies, we cover the transceiver design and optical amplifier technologies to maximize optical fiber capacity. OCIS codes:

Digital back-propagation for nonlinearity mitigation in distributed Raman amplified links

The performance of digital back-propagation (DBP) for distributed Raman amplified optical communication systems is evaluated through analytical models and numerical simulations, and is compared with conventional lumped amplifier solutions, such as EDFA. The complexity of the DBP algorithm including the characteristic signal power profile of distributed Raman amplifiers is assessed. The use of full-field DBP in distributed Raman amplified systems leads to 1.3 dB additional gain with respect to systems employing lumped amplification, at the cost of only a 25% increase in complexity

Self-Suppression of Signal-Signal Beating Interference using a Split-Carrier Transmitter

A transmitter-side carrier tone is applied to suppress SSBI in a 112 Gb/s double sideband IM/DD system using a split-carrier transmitter. This novel, low-complexity approach achieves comparable performance to a computationally-intensive linearised receiver without any additional opto-electronic hardware or linearisation DSP

Improved spectral characteristics of a single-mode semiconductor laser using a fibre grating and a reduced laser diode length

Use of a reduced laser diode length with a fibre Bragg reflector leads to decreased mode-hopping and a factor of 3 improvement in temperature stability of the lasing wavelength over Δ T=22°C. Single frequency output power of 1.7 mW in the fibre with 45 dB side mode suppression was obtained

A Closed-form Expression for the Gaussian Noise Model in the Presence of Raman Amplification

A closed-form model for the nonlinear interference (NLI) in Raman amplified links is presented, the formula accounts for both forward (FW) and backward (BW) pumping schemes and inter-channel stimulated Raman scattering (ISRS) effect. The formula also accounts for an arbitrary number of pumps, wavelength-dependent fibre parameters, launch-power profiles, and is tested over a distributed Raman-amplified system setup. The formula is suitable for ultra-wideband (UWB) optical transmission systems and is applied in a signal with 13 THz optical bandwidth corresponding to transmission over the S-, C-, and L- band. The accuracy of the closed-form formula is validated through comparison with numerical integration of the Gaussian noise (GN) model and split-step Fourier method (SSFM) simulations in a point-to-point transmission link

A Closed-form Expression for the Gaussian Noise Model in the Presence of Raman Amplification

A closed-form model for the nonlinear interference (NLI) in Raman amplified links is presented, the formula accounts for both forward (FW) and backward (BW) pumping schemes and inter-channel stimulated Raman scattering (ISRS) effect. The formula also accounts for an arbitrary number of pumps, discrete or distributed Raman amplification setup, wavelength-dependent fibre parameters, and launch power profiles. The formula is suitable for ultra-wideband (UWB) optical transmission systems and is applied in a system with 13 THz optical bandwidth corresponding to transmission over the S-, C-, and L- band. The accuracy of the closed-form formula is validated through comparison with numerical integration of the Gaussian noise (GN) model and split-step Fourier method (SSFM) simulations in a point-to-point transmission link.Comment: arXiv admin note: text overlap with arXiv:2210.0906

A Modulation-Format Dependent Closed-form Expression for the Gaussian Noise Model in the Presence of Raman Amplification

A closed-form expression that estimates the nonlinear interference of arbitrary modulation formats in Raman amplified links is presented. Accounting for any pumping schemes and inter-channel stimulated Raman scattering effect, the formula is applied to an optical bandwidth of 20~THz and validated using numerical simulations.Comment: Presented at European Conference on Optical Communications (ECOC) 202