Erlangen 2018 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 30: Optomechanics II

Q 30.5: Talk

Tuesday, March 6, 2018, 15:00–15:15, K 0.023

Broadband optomechanically self-aligned coupling to liquid-filled hollow-core photonic crystal fibre using a fused silica nanospike — •Richard Zeltner, Riccardo Pennetta, Shangran Xie, and Philip St.J. Russell — Max Planck Institute for the Science of Light, Erlangen, Germany

Hollow-core photonic crystal fibre (HC-PCF) confines and guides light in a hollow core that can be filled with low index media, allowing efficient light-matter interactions over long path lengths. HC-PCF thus provide a promising platform for a variety of optofluidic experiments, for example in photochemistry and spectroscopy. Many applications require efficient and stable coupling of broadband light into the core modes, which can be challenging if free-space or butt-coupling are used. Here we introduce a new technique that permits broadband, optomechanically self-aligned light delivery into a liquid-filled HC-PCF. A fused silica nanospike, fabricated by thermally tapering and chemically etching a single-mode fibre to a final tip diameter of 350 nm, is inserted into the HC-PCF. When a strong laser beam is launched into the nanospike via the untapered fibre end, optomechanical interactions between the nanospike and the HC-PCF modes gives rise to strong optical forces that align the tip at core centre. With the tip trapped at core centre, a broadband (bandwidth of 500 nm) supercontinuum signal could be efficiently, and close to achromatically, launched into the HC-PCF. The optomechanical trapping forces render the coupling robust against perturbations and Fresnel back-reflections are decreased to insignificant levels compared to free-space or butt-coupling.