Pulsed lasers for wavelength versatile microscopy

Multiphoton microscopy uses pulsed lasers to excite fluorescent dye markers in biological samples. Different wavelengths are required to excite different dyes, so using multiple dyes in a single sample requires a pulsed laser that can provide many independent outputs simultaneously. An OPO converts short wavelength pump photons into longer wavelength signal and idler photons in a nonlinear crystal. By constructing a resonant cavity at the signal wavelength, a source of tuneable infrared light can be realised. A single laser pumping two nonlinear crystals will produce independent signal wavelengths, ideal for versatile nonlinear microscopy. This PhD project will develop multi-crystal OPOs pumped by a femtosecond Ti:sapphire laser.

The practical element of this project will be supported with Matlab modelling. The phase-matching properties of the nonlinear crystals will be tailored to deliver broad bandwidths and wide tuneability. The parametric processes in the OPO will be modelled using the coupled-wave and full-field equations. PhD training will be supported by a number of modules at Heriot-Watt and SUPA, specifically B21NT1 (Microscopy & multiphoton processes components), B21FN2 (Nonlinear Optics component) and Ultrafast Photonics (remote learning SUPA course). Should relevant summer schools become available, these will also be pursued.