Electrically Pumped Broad Band and Vertical Cavity Semiconductor Dilute Nitride Amplifiers for Metro and Acess Networks

Optical fibre communications are used for transmission of voice, data and video throughout the world today. As the demand for broadband services in the access segment of the industry continues to increase, network operators face increased challenges to deliver higher bandwidths since customers are often not prepared to pay significantly more than at present for these services. Cost-effective, well-managed metropolitan networks are therefore required that have sufficient capacity and flexibility to respond to future demand. For future optical metro and access networks it is essential to develop cheap, reliable components with good performance at the wavelength of 1.3 micron that allows transmission of high bandwidths over fibre. Such networks are very cost-sensitive, since some components serve just one customer instead of being shared by large numbers of users as in, for example, a trans-oceanic cable. There is therefore a pressing need for optical components that can offer the required functionality at low cost with high bandwidth. In this context, components based on the dilute nitride (GaInNAs/GaAs) system are predicted to offer significant advantages over devices using the more conventional GaInAs/InP system. In particular the broad gain spectrum of GaInNAs in the wavelength range 1.3 - 1.55 micron makes it especially suitable for use in planar semiconductor optical amplifiers, whilst the aspects of growth on GaAs and integration with GaAs/AlGaAs DBRs are attractive for applications in vertical-cavity devices. Initial work in this area has been successful, with the demonstration of edge-emitting lasers and vertical-cavity surface-emitting lasers (VCSELs) with good light output and fast modulation speed. The current proposal seeks to further exploit the device potential of dilute nitrides by focussing on the design and characterization of two specific photonic devices: an edge emitting broad band semiconductor optical amplifier (BBSOA) and an electrically pumped vertical cavity semiconductor optical amplifier (VCSOA). This joint proposal between Essex and Bristol will be productive, cost-effective and wide-ranging, covering both VCSOAs and BBSOAs for different metro and access applications in the 1.3 micron communications window.