Current research / employment Invention of hollow-core photonic crystal fibers (HC-PCF) has been a milestone for studies in light-matter interactions and in particular stimulated Raman scattering (SRS). Tight confinement of both intense laser light and Raman-active medium in the micron-size fiber core has led to extremely high frequency conversion efficiencies as well as lowering the threshold for the SRS process by several orders of magnitude. The objective of this thesis is to investigate novel aspects of stimulated Raman scattering in gas-filled hollow-core photonic crystal fibers, such as phase-matching via intermodal SRS and frequency comb generation.