Product/Research Description

At St Andrews one of the principal research activities relates to the development, assessment and application of a wide range of laser systems. These include picosecond/femtosecond tunable lasers, diode-pumped solid-state minilasers and microchip lasers, and specialist diode lasers. Particular examples are picosecond and femtosecond Ti:sapphire, Cr:LiSrAIF6 (Cr:LiSrGaF2), Cr:YAG and NaCI:OH, KCI:TI colour-centre lasers, Q-switched and CW Nd:YAG (YLF) minilasers and green, blue Nd:YVO4 (YAG) microchip lasers, Q-switched and modelocked diode lasers and a range of line-narrowed external-cavity-diode lasers.

A major complementary effort is directed towards frequency down-conversion techniques and state-of-the-art optical parametric oscillators (OPOs) have been demonstrated for the femtosecond, picosecond, nanosecond and CW regimes. The picosecond OPO system having tunability in the near/mid-infrared is especially relevant to ongoing time-resolved studies of semiconductor structures and devices. Specific ultracompact, external-cavity, high performance, near-infrared diode laser configurations are also being developed as optical excitation sources in atom trapping and guiding applications. Red and violet versions of these external-cavity diode lasers are also being developed for high-resolution spectroscopy and nonlinear optics.

Specialised Skills and Facilities

Project work on the control and implementation of Laguerre-Gaussian transverse laser modes, has led to demonstration of enhanced-performance procedures in optical tweezing and very interestingly, to the observation of the new phenomenon of “optical spanners”. This work is ongoing where current interests have been extended to new optical mechanisms for manipulating particles and for specific biological applications.

Within our prgrammes in fundamental quantum electronics, there is an ongoing project in the study of electromagnetically-induced transparency. Recent theoretical and experimental studies have led to the identification and characterisation of a new electromagnetically-induced self-focusing bands that are not currently accessible using conventional lasers.

Research is also being carried out in the field of optical and optoelectronic diagnostics, miniaturised autocorrelators, real-time frequency-resolved optical gating and sonogram schemes.