The primary objective is to investigate optical fibre sub-systems for use in ultra-short pulse generation, amplification, switching and transmission to assess and evaluate their potential for future use in the IBC network. This project is targeted at designing and evaluating elements for systems with a throughput of greater than 10 Gbit/s. Two subsidiary goals have been defined. These are:
- To demonstrate the generation of stable, tuneable, ultra-short pulses with mode-locked optical fibre lasers.
- To investigate ultra short pulse transmission, specifically soliton transmission, and to develop the necessary special optical fibres, components and sub-systems.
The primary objective of the research was to investigate optical fibre subsystems for use in ultrashort pulse generation, amplification, switching and transmission to assess and evaluate their potential for future use in the integrated broadband communications (IBC) network. This research was targeted at designing and evaluating elements for sytems with a throughput of greater than 10 gigabits per second. Two subsidiary goals were defined:
to demonstrate the generation of stable, tuneable, ultrashort pulses with mode locked optical fibre lasers;
to investigate ultrashort pulse transmission, specifically soliton transmission and to develop the necessary special optical fibres, components and subsystems.
The research has achieved the following results:
a widely tuneable actively mode locked fibre ring laser giving transform limited, high peak power, picosecond pulse;
ultrashort (30 fs) pulses from a passively mode locked laser system and a fibre ring laser giving soliton pulses of 700 fs to 4 ps;
60 to 120 gigabits per second continuous wave (CW) soliton train generation and transmission of a 64 gigabits per second soliton train over 2.2 km;
the amplification of femtosecond optical solitons in erbium doped fibre amplifier (EDFA);
soliton compression in a fibre of steadily decreasing dispersion;
the production of special fibres including erbium(3+) doped polarization preserving and dispersion decreasing fibres;
the development of a polarization preserving 980 and 1550 nm wavelength decision multiplexer (WDM) coupler with variable splitting ratio;
the definition of design parameters for all fibre components including high speed modulators, optically controlled switches and filters.
The project is structured into two main areas, investigating ultra-short pulse generation and transmission. A major part is directed at the investigation and development of quality ultra-short pulse sources, supported by advanced fibre component development of an advanced model mode-locked erbium doped fibre ring laser (EFRL) and development of a high repetition rate fibre soliton source.
In parallel, the investigation of ultra-short pulse transmission in fibres is undertaken. This includes both modelling and experimental demonstrations of optical pulse-shaping, fibre dispersion compensation, the Gordon-Haus limit, soliton transmission and fibre based 40Gbit/s modulation.
This work is supported by the development of special fibres and advanced components. Stabilisation of the erbium doped fibre laser requires polarisation maintaining fibres and quality polarising components. Additional supporting activities are undertaken to develop non-linear polymers for high speed switching applications.
- Stable, high quality, wide wavelength tuneable, ultra-short pulse generation using EFRL.
- High quality soliton pulse generation at 40 Gbit/s.
- Development of 40 Gbit/s modulation techniques and transmission testbed.
- Future European requirements for high bit-rate soliton transmission.
The initial stages of the project have focused toward development of high quality ultra-short pulse sources for use in future high capacity systems. Based on the successful source development, the project is examining propagation and transmission aspects of high bit rate systems. The anticipated impact from the project is the development of quality sources and investigation of ultra-short pulse transmission capabilities at 40Gbit/s and beyond appropriate for future European communication networks.
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