The WELCOME project develops advanced, fully packaged and system tested quantum well (QW) based discrete and monolithically integrated components of enhanced performance needed for optical IBC implementation. The focus is on 1.55 um transmitters and new 0.98 um pump lasers, space switches and picosecond optical pulse sources for high speed systems operating at bit rates greater than or equal to 10 Gbit/s.
The overall objective of the project was to develop the following highly advanced quantum well components for high speed transmission systems (greater than or equal to 10 gigabits per second):
transmitter modules based on quantum well (QW) lasers;
optical modulators for external digital modulation;
a monolithically integrated QW single mode laser modulator for intensity modulation (IM) transmission systems;
second generation system qualified 980 nm pump laser modules for erbium doped fibre amplifiers (EDFA).

The following progress has been achieved:
a QW distributed feedback (DFB) laser has been realised based on 2 inch technologies (the laser module worked well in a system testbed at 10 gigabits per second nonreturn to zero (NRZ));
QW DBF lasers have been designed for 10 gigabits per second frequency shift keying (FSK) modulation;
VUG SIBH lasers have been realised with strained QWs;
QW electroabsorption modulators (EAM) have been fabricated with bandwidths in excess of 20 GHz in combination with a low drive voltage of lV;
basic technologies for the longitudinal integration of a QW DBF laser modulator have been developed using low pressure (LP) metal organic vapour phase epitaxy (MOVPE);
a package for the laser modulator chip and a 3-terminal submount with microstrip and coplanar GSG transmission line were developed for gigabits per second operation;
980 nm QW pump lasers for EDFAs were realised in the material systems gallium indium arsenide/gallium arsenide/aluminium gallium arsenide and gallium indium arsenide/gallium(indium)arsenic(phosphorus)gallium indium phosphide by molecular beam epitaxy (MBE) and gas source molecular beam epitaxy (GSMBE) respectively;
QW EAMs have been tested in an EDFA based transmission system using standard and dispersion shifted fibres.
Technical Approach

-Transmitter modules based on QW DFB laser chips with extremely low parasitics for intensity modulation (IM) and frequency shift keying (FSK) systems operating at 10 Gbit/s. Strained-layer QW structures and injection locking techniques for chirp reduction are used.
- Discrete and potentially integrable QW modulators with reduced chirp and high modulation capability for IM systems operating at 10-20 Gbit/s based on electric field induced changes in the dielectric function by the Quantum Confined Stark/Wannier Stark Effect (QCSE/WSE) and on the advanced BRAQWET concept.
- Transmitter modules based on highly advanced monolithically integrated QW DFB laser/electroabsorption modulator (EAM) chips for greater than or equal to 10 Gbit/s IM systems.
- Monolithically integrated pico-second optical pulse sources for applications in 20 Gbit/s systems based on OTDM/non-linear (soliton) transmission.
- 2nd generation 0.98 um pump laser modules for Erbium doped fibre amplifiers based on specific QW structures considering A1-based and A1-free material systems.
- QW components test in a system to qualify, feed in component data to system design and propose CPRs/CFSs.

Key Issues

- Development of technology platform for quantum well based components and photonic ICs.
- Realisation of 1.55 um transmitters and second generation 0.98 um pump lasers for high speed transmission / distribution systems operating at bit rates greater than or equal to 10 Gbit/s.
- Component tests and contribution to CPRs and CFSs.

Expected Impact

It is intended to transfer the QW technology from the project to the production units of the industrial partners for further development leading to low cost production.