High field terahertz radiation : conduits to synchronized hyper spectral systems

Abstract

After the first experiments of nonlinear phenomena in optics, the development of the mode-locked laser has led to rapid proliferation of the study of nonlinear frequency conversion techniques-enabling the conversion of light from the infra-red, all the way to the soft X-Ray region. However, accessing the hard X-ray region remains elusive, and the domain of specialized facilities. The key insight to accessing hard X-rays optically may not be in seeking to convert optical frequencies upward, but rather downward to frequencies spanning a 100 to 10,000 GHz. This would enable unprecedented control of electrons and consequently the generation of hard X-rays. The efficient optical conversion to terahertz radiation would thus open up the possibility of highly synchronized multi-spectral systems to transform the landscape of scientific investigation and medicine among others. In this thesis, the problem of efficient conversion is tackled theoretically. A montage of novel computational techniques, analyses, device proposals and physical mechanisms culminate in record breaking experimental demonstrations with efficiencies, an order of magnitude larger than prior art. The thesis further paves the way for even greater improvements, by another order of magnitude. The underlying science of cascaded difference frequency generation, expounded here would be of significant value to terahertz generation in chip-scale systems for future applications such as Quantum computing, chip-scale accelerators and X-ray sources.