‘Hair-thin’ optical fibers promise performance innovations

26 Jan 2021

University of Bonn team makes fine fibres simply; predicts applications in quantum, sensors, and gas detection.

Scientists at the University of Bonn, Germany, have developed hair-thin optical fibre filters in a very simple way. These are not only extremely compact and stable, but also wavelength-tunable. This means they can be used in quantum technology and as sensors for temperature or for detecting atmospheric gases.

The work is described in Optics Express.

Optical resonators or filters are key components cutting out narrow spectral lines from white light sources. In the simplest case such filters are built from two opposing mirrors passing light back and forth as precisely as the pendulum of a clock. The wavelength of the filtered light is set by the mirror separation.

Suitable mirrors have been integrated with the ends of hairlike fibers for some time. Researchers of the University of Bonn have succeeded in constructing simply such hairlike optical fiber resonators.

These are not only extremely compact and stable but also allow the tuning of their wavelength. The researchers have glued the fiber ends carrying the mirrors into a common ferrule which can be stretched by means of a piezo crystal and hence control the mirror separation.

‘Decisive technology’

“The miniaturised optical filter makes a further contribution to making photonics and quantum technologies the decisive technology of the 21st century,” said Prof. Dr. Dieter Meschede from the Institute of Applied Physics at University of Bonn.

The scientist is a member of "Matter and light for quantum computing" (ML4Q) Cluster of Excellence of the Universities of Bonn and Cologne and RWTH Aachen University and is also a member of the Transdisciplinary Research Area “Building Blocks of Matter and Fundamental Interactions” at the University of Bonn.

Miniaturized highly stable optical precision filters are promising multiple applications: they can store light energy within such a small volume such that already single photons can be efficiently stored and manipulated.

Their high sensitivity suggests to build extremely compact and selective sensors, e.g. for detecting atmospheric gases. Using even more stable materials for the ferrule tiny optical clock works with extremely high frequency stability may be built.

Participating institutions

In addition to the University of Bonn, the Universidad de Guanajuato (Mexico) is also involved in the study. The project is funded within the FaResQ project of the program key components for quantum technology of the German Federal Ministry of Research and Technology (BMBF). The infrastructure for manufacturing and processing the fibres takes place in the Bonn Fiberlab, which is operated by the ML4Q Cluster of Excellence.