Pulsed lasers for wavelength versatile microscopy

多光子显微镜使用脉冲激光激发生物样品中的荧光染料标记。需要不同的波长来激发不同的染料，因此在单个样品中使用多种染料需要可以同时提供许多独立输出的脉冲激光器。OPO在非线性晶体中将短波长泵浦光子转换成较长波长信号光子和空闲光子。通过在信号波长处构造谐振腔，可以实现可调谐红外光的源。单激光泵浦两个非线性晶体将产生独立的信号波长，非常适合多功能非线性显微镜。本博士项目将开发飞秒钛宝石激光泵浦的多晶OPO。该项目的实际部分将由Matlab建模支持。非线性晶体的相位匹配特性将被定制以提供宽带宽和宽调谐。在OPO的参数过程将使用耦合波和全场方程建模。博士培训将由赫瑞瓦特和SUPA的一些模块提供支持，特别是B21NT1（显微镜和多光子过程组件），B21FN2（非线性光学组件）和超快光子学（远程学习SUPA课程）。如果有相关的暑期学校，也将开展这些活动。

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.