Advanced Solid-State Sources and Applications

Fibre lasers and amplifiers were once regarded as relatively low power devices with application areas dominated by optical communications and sensing.  However, over the last decade there has been increasing recognition that rare-earth-ion doped fibres also offer a very attractive route to very high laser powers.  The chief benefits of a fibre gain medium are derived directly from its geometry which offers very simple thermal management and a high degree of immunity from thermal effects which are often so detrimental to laser performance in other types of laser.  This feature in combination with the use of cladding-pumping and high-brightness diode pump sources (see below) has resulted in a dramatic rise in the output power fibre-based laser and amplifier sources.  In fact, the rate of progress has been so rapid that it has fuelled thoughts that fibre laser technology will replace conventional solid-state laser technology in many fields of application.  In spite of these developments there are still many challenges, as well as opportunities to improve performance, extend the range of operating wavelengths and to increase functionality.  Our current research is exploring the use of novel fibre geometries including helical-core (or twisted-core) fibres, ribbon fibres, multi-core fibres, cladding-pumped long-rod fibres and beam combination schemes to allow scaling to higher powers and higher pulse energies whilst preserving excellent beam quality and the well-behaved operating characteristics of lower power devices.