Berlin 2014 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 16: Poster: Quantum information, micromechanical oscillators, matter wave optics, precision measurements and metrology

Q 16.32: Poster

Monday, March 17, 2014, 16:30–18:30, Spree-Palais

Laser-machined optical cavities of high finesse — •Manuel Uphoff, Manuel Brekenfeld, Stephan Ritter, and Gerhard Rempe — Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching

Single atoms strongly coupled to optical cavities have shown great potential for light-matter interfaces at the single excitation level. The strength of the coupling is inversely proportional to the square root of the mode volume of the cavity, which depends on the radius of curvature of the mirrors. For superpolished substrates the radius of curvature is limited by the polishing process. Laser ablation with a CO₂-laser offers a reduction of the radius of curvature by two orders of magnitude.

We report on the fabrication of near-spherical surfaces on the end facets of optical fibers with a CO₂-laser at 9.3 µm wavelength. This method enables concave structures with a diameter approaching the size of the fiber, which show a residual roughness below 0.3 nm rms. Cavities using two of these fibers with a highly reflective, dielectric coating show a finesse of up to 190000. We will discuss the effects of mirror ellipticity on cavity birefringence and the progress towards the fabrication of fiber-based cavities optimized for applications in quantum information processing.