Tijmen G. Euser

Fluorescence-based remote irradiation sensor in liquid-filled hollow-core photonic crystal fiber

We report an irradiation sensor based on a fluorescent “flying particle” that is optically trapped and propelled inside the core of a water-filled hollow-core photonic crystal fiber. When the moving particle passes through an irradiated region, its emitted fluorescence is captured by guided modes of the fiber core and so can be monitored using a filtered photodiode placed at the fiber end. The particle speed and position can be precisely monitored using in-fiber Doppler velocimetry, allowing the irradiation profile to be measured to a spatial resolution of ∼10 μm. The spectral response can be readily adjusted by appropriate choice of particle material. Using dye-doped polystyrene particles, we demonstrate detection of green (532 nm) and ultraviolet (340 nm) light.

RF-dressed Rydberg atoms in hollow-core fibres

The giant electro-optical response of Rydberg atoms manifests itself in the emergence of sidebands in the Rydberg excitation spectrum if the atom is exposed to a radio-frequency (RF) electric field. Here we report on the study of RF-dressed Rydberg atoms inside hollow-core photonic crystal fibres, a system that enables the use of low modulation voltages and offers the prospect of miniaturised vapour-based electro-optical devices. Narrow spectroscopic features caused by the RF field are observed for modulation frequencies up to 500 MHz.

Long-range optical binding in a hollow-core photonic crystal fiber using higher order modes

We report long-range optical binding of multiple polystyrene nanoparticles (100-600 nm in diameter) at fixed interparticle distances that match multiples of the half-beat-lengths between the lowest order modes of a hollow-core photonic crystal fiber. Analysis suggests that each nanoparticle converts the incoming optical mode into a superposition of co-propagating modes, within the beat pattern of which further particles can become trapped. Strikingly, the entire particle arrangement can be moved over a distance of several cm, without changing the inter-particle spacing, by altering the ratio of backward-to-forward optical power. Potential applications are in multi-dimensional nanoparticle-based quantum optomechanical systems.

Controlled Particle Guidance in a Liquid-Filled Single-Mode Hollow-Core Photonic Crystal Fiber

We present controlled optical trapping and guidance of silica microparticles in the fundamental mode of D2O-filled hollow-core PCF, and show that a particle can be held stationary against an opposing fluid flow using optical propulsion.

Long-range optical trapping and binding of microparticles in hollow-core photonic crystal fibre

Optically levitated micro- and nanoparticles offer an ideal playground for investigating photon–phonon interactions over macroscopic distances. Here we report the observation of long-range optical binding of multiple levitated microparticles, mediated by intermodal scattering and interference inside the evacuated core of a hollow-core photonic crystal fibre (HC-PCF). Three polystyrene particles with a diameter of 1 µm are stably bound together with an inter-particle distance of ~40 μm, or 50 times longer than the wavelength of the trapping laser. The levitated bound-particle array can be translated to-and-fro over centimetre distances along the fibre. When evacuated to a gas pressure of 6 mbar, the collective mechanical modes of the bound-particle array are able to be observed. The measured inter-particle distance at equilibrium and mechanical eigenfrequencies are supported by a novel analytical formalism modelling the dynamics of the binding process. The HC-PCF system offers a unique platform for investigating the rich optomechanical dynamics of arrays of levitated particles in a well-isolated and protected environment.Optical trapping: multiple particle bindingMicroparticles placed inside the evacuated hollow core of a photonic crystal fibre can be bound together by optical forces and moved as a single entity along the fibre by light. Dmitry Bykov and coworkers from the Max Planck Institute for the Science of Light in Erlangen, Germany performed the experiments with three, 1 µm-diameter polystyrene particles. When light pulses from a Ti:Sa laser were injected into both ends of the photonic crystal fibre, intermodal interference was found to be able to bind the three particles together, with a particle spacing of ~40 µm. It is thought that by adjusting parameters such as the fibre design and the laser pulse duration, chirp and power it should be possible to increase both the inter-particle binding distance and the number of bound particles.

Excitation of higher-order modes in optofluidic hollow-core photonic crystal fiber

Higher-order modes are controllably excited in water-filled kagomè-, bandgap-style, and simplified hollow-core photonic crystal fibers (HC-PCF). A spatial light modulator is used to create amplitude and phase distributions that closely match those of the fiber modes, resulting in typical launch efficiencies of 10–20% into the liquid-filled core. Modes, excited across the visible wavelength range, closely resemble those observed in air-filled kagomè HC-PCF and match numerical simulations. These results provide a framework for spatially-resolved sensing in HC-PCF microreactors and fiber-based optical manipulation.

Fluorescence-based flying-particle sensor in liquid-filled hollow-core photonic crystal fiber

We present a novel irradiation sensor based on a fluorescent microparticle that is optically guided inside the core of a liquid-filled photonic crystal fiber. We demonstrate irradiance measurements with spatial resolution of ~10 μm.