IISA

 

Implanted Integrated Saturable Absorbers for
Ultra-high Speed Optical Transmission

E. Burr, S.F. Kong, M.I. Pantouvaki

Project Support

Nortel Networks

EPSRC

 

Acknowledgements

Surrey Centre for Research in Ion Beam Applications

EPSRC Central Facility for III-V Semiconductors

Rutherford Appleton laboratory Central Microstructure Facility

 

Introduction

Optical network channel rates of 10 Gb/s are in widespread commercial use. However, future network traffic demand will require a new technology to meet the additional performance requirement. The issue of achieving long-distance Dense Wavelength Division Multiplex (DWDM) transmission at bit-rates of 40 Gb/s and above per channel is vital for reducing size, power requirements and cost in future optical communication networks. However, signal regeneration to minimise the effects of transmission impairments assumes greatly increased importance at these higher bit-rates.

 

Objectives

This project aims to design and fabricate an integrated semiconductor laser amplifier/implanted saturable absorber (SLA/ISA) device. The SLA/ISA has great potential to extend the reach of long distance high bit-rate networks without requiring the use of current optical-electronic-optical signal regenerators that are limited by the electronic circuit bottleneck. This all-optical SLA/ISA device would also be simpler than other fibre-based all-optical regenerator techniques.

 
Results

Our modelling demonstrates the feasibility of an 80 Gb/s channel rate transmission over trans-oceanic distance with the use of saturable absorber regenerators after each amplifier and dispersion decreasing fibre (DDF), to compensate for the self-phase modulation decrease due to fibre loss.

 

As shown in the Figure 1, the Q factor falls below a value of 6 (corresponding to a bit error rate of 10-9) at a distance of 1,200 km without saturable absorbers. With the saturable absorbers, the error-free transmission distance increases to values greater than 8,350 km. The transmission distance increases further to 9,150 km if Amplified Spontaneous Emission (ASE) noise is not included in the model, and to greater than 10,000 km if the Raman effect is taken out as well.

 

Figure 1 Q factor as a function of distance showing the increase in error free transmission distance to over 8,000 km when saturable absorbers are included in the system (Inset shows eye diagrams after 50 km and 8,350 km). Also shown (dashed line), is the transmission performance without saturable absorbers: the error free transmission distance drops to 1,200 km. Receiver bandwidth = 40 GHz.