Products and applications

The Bonn Fiber Lab provides a range of fiber-based photonic tools for state-of-the-art experiments in quantum optics:

Fiber cavities for quantum communication

Fiber cavities consist of two mirrors fabricated directly onto the end faces of optical fibers [12]. These fiber mirrors are produced by micro-machining with a CO2 laser and subsequent optical coating. A fiber cavity provides the small mode volume and the high finesse that are required for the strong coupling of light to material quantum objects such as atoms [5], trapped ions [1] or quantum dots. Together with the efficient coupling to single-mode optical fibers, quantum nodes of future quantum networks [10] as well as single photon sources [8] have been realized.

Monolithic fiber cavities for gas spectroscopy

Two optical fiber mirrors are inserted into a glass ferrule glued on a piezoelectric actuator, to form a very compact monolithic fiber cavity. © Carlos Saavedra / Universität Bonn (, OSA - OA)

For trace gas spectroscopy and the detection of weak molecular transitions, the sensitivity enhancement offered by optical resonators is well established. The monolithic fiber cavities developed by the Bonn Fiber Lab [11] offer a strongly miniaturized solution with high passive stability (insensitivity to vibrations) that lends itself to compact gas spectrometers. For example, detection of Oxygen via absorption spectroscopy on a weak “overtone” transition has been achieved in an active volume of less than a cubic millimeter [15]. A centimeter-sized sensor using cavity-enhanced photo-thermal spectroscopy was used to detect methane at mid-infrared wavelengths in collaboration with Prof. Dr. Karol Krzempek from Poland. It achieved a sensitivity in the ppm range, comparable to much larger sensor setups [18].

3D-printed membranes on fiber mirrors for quantum optomechanics

Integrating mechanical elements into fiber cavities offers viable routes to a manifold of applications like quantum limited sensing of forces and sound, or mechanical storage and transduction of information between different optical or even microwave fields. Collective coupling of multi-mode mechanical resonators is expected to boost the interaction between optical and mechanical modes. However, combining more than two membranes in a single optical cavity has been elusive with conventional micromechanical resonators. Merging fiber cavities with the technique of 3D direct laser writing (3D DLW) allows the fabrication of almost arbitrary structures and even stacks of multiple mechanical membrane resonators [17]. Incorporating straining, different 3D DLW resists, and designing and testing cavity-integrated multi-mode mechanical resonators is an active research effort in the Bonn FiberLab.

Lenses and dielectric microstructures on optical fibers

With the 3D direct laser writing system lenses and other beam-forming elements have been written directly on fiber and-faces. Such modified fibers permit miniaturized illumination and collection optics close to atoms, ions and solid-state emitters for simplified control and read-out from close distance, less bulky optics, and future integration into all-fiber optical setups.

Patterned metallization of optical fibers for integrated electrodes and near-field antennae

The functionality of optical fiber resonators can be further enhanced by fabricating metallic conductors and electrodes directly on the end faces and the sides of the optical fibers. For example, this technique could be used to integrate the electrodes of an ion trap directly into the optical fiber resonator. Another potential application is the implementation of RF and microwave antennae, which permit particularly efficient manipulation of atomic quantum systems using magnetic near-fields.

Quantum dots coupled to fiber cavities

Advancements in quantum communication technologies demand the development of robust single photon sources. Indium-Arsenide quantum dots, which act akin to atomic systems, have been recognized as a bright source for single photons of high quality. Integration into an open, tunable fiber micro-cavity, allows spectral and spatial selection of individual emitters. Such a cavity enhances the rate and directionality of single photon emission, allowing for efficient single photon generation and direct coupling into optical fibers.

Transition metal dichalcogenide monolayers in fiber cavities

More information coming soon.

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