Colm O'Riordan

Semiconductor Optical Amplifier Pattern Effect Suppression Using a Birefringent Fiber Loop

The capability of a birefringent fiber loop to suppress the pattern effect in a semiconductor optical amplifier is experimentally demonstrated. The results verify that compared to direct signal amplification this scheme achieves reduced amplitude modulation, enhanced eye diagram extinction ratio, pulse reshaping, tolerance to long string of spaces, low power penalty, and extended input power dynamic range.

Simple model for optical pulse propagation in a reflective semiconductor optical amplifier

A simple time-domain model is presented that can predict optical pulse propagation in reflective semiconductor optical amplifiers (RSOAs). The RSOA saturation energy, effective lifetime and material gain coefficient parameters used in the model are determined using experimental measurements of the input and output pulse temporal profiles to the RSOA and Levenberg-Marquardt parameter extraction algorithm. The model accurately predicts the propagation of 50.4 ps pulsewidth high-power pulses in the RSOA.

Actively Mode-locked Multiwavelength Fibre Ring Laser Incorporating a Lyot Filter, Hybrid Gain Medium and Birefringence Compensated LiNbO3 Modulator

A lyot filter based actively mode-locked multiwavelength fibre ring laser with a hybrid gain medium, consisting of an SOA and EDFA, is presented. Simultaneous mode-locking of up to 8 wavelength channels at 10 GHz is realised using a LiNbO3 based Mach-Zehnder intensity modulator. A wavelength channel spacing of 100 GHz is obtained via appropriate tuning of the Lyot filter length. The effect of modulator birefringence on the performance of the laser spectrum is investigated and a simple method to increase spectral stability is proposed and demonstrated.

Repetition rate and wavelength-tunable all-optical actively mode-locked fibre ring laser based on a reflective semi-conductor optical amplifier

A repetition rate- and wavelength-tunable fibre ring laser that utilises a reflective semi-conductor optical amplifier as both a gain and mode-locking element is presented. Moreover, 10.3 ps pulses at 10 GHz repetition rate are obtained across a 30 nm tuning range covering the entire C-band. The repetition rate is tunable up to 30 GHz via rational harmonic mode-locking. A comparison is made using a conventional semi-conductor optical amplifier as the gain and mode-locking element. It is shown that the reflective semi-conductor optical amplifier requires in excess of 5 dB less average pump pulse power in order to achieve the optimum mode-locking condition, for achieving the narrowest output pulse width, thereby relaxing the requirement for a complex and expensive pump pulse source.

Triple-wavelength fiber ring laser based on a hybrid gain medium actively mode-locked at 10 GHz

A fiber ring laser based on a hybrid gain medium that produces three simultaneously mode-locked wavelength channels is presented. The lithium niobate based modulator used to actively mode-lock the laser cavity at 10 GHz is birefringence compensated to reduce its polarization sensitivity. A Lyot filter defines the lasers multiwavelength spectrum which has a wavelength spacing of 1 nm. The polarization sensitive nature of the laser cavity and its affect on the performance of the laser is discussed.

SOA and Lyot filter based multiwavelength actively mode-locked fibre ring laser with modulator birefringence compensation

This paper describes an semiconductor optical amplifier (SOA) and Lyot filter based multiwavelength actively mode-locked fibre ring laser. This laser is capable of producing 18 mode-locked wavelength channels each containing a 2 GHz repetition rate pulse train having a pulse width of approximately 95 ps.