UC Riverside

This thesis describes the development and experimental testing of the cryogenic Brillouin – Mandelstam light scattering spectrometer system. The advanced features of the spectrometer system include the specially designed rotating microscopy stage and imaging system for measuring the energy dispersion of phonons and magnons in samples with smaller dimensions than those acceptable for conventional spectrometers. In this thesis, I provide an overview of the Brillouin light scattering fundamentals, summarize the principles of operation of the tandem Fabry-Perot interferometer, and describe the steps in the hardware assembly of the Brillouin – Mandelstam spectrometer system. Details of the beam-path design, optical assemblies, and sample holders are also provided. In order to test the operation of the spectrometer, I acquired light scattering spectra from silicon, diamond, pure epoxy, and graphene-epoxy composites at various light incident angles and in the temperature range from 4 K to 300 K. The characteristic features of the measured spectra and experimental capabilities of the spectrometer are discussed in details. The developed and built cryogenic Brillouin – Mandelstam spectrometer system is expected to become an essential tool enabling cutting-edge research, advanced industrial material characterization, and graduate student training.