TY - JOUR

T1 - Na-Faraday rotation filtering: The optimal point

AU - Kiefer, Wilhelm

AU - Löw, Robert

AU - Wrachtrup, Jörg

AU - Gerhardt, Ilja

N1 - Funding information: We thank Widmann, M., University of Stuttgart, for supplying the 3D representation of our experimental configuration. We acknowledge the work by Schreiber, F., University of Stuttgart, for producing the quartz glass cells. Ben Hughes is acknowledged for proof-reading the manuscript. We further acknowledge the support by the Max Planck Society (Wrachtrupp, J., Max Planck fellowship) and the EU via the project SIQS. The authors acknowledge the courtesy of Harrell, Krueger and She of the Colorado State University for permission to use ‘‘FaradayFilter3.pro’’ copyright March 24, 2008 as food for thought.

PY - 2014

Y1 - 2014

N2 - Narrow-band optical filtering is required in many spectroscopy applications to suppress unwanted background light. One example is quantum communication where the fidelity is often limited by the performance of the optical filters. This limitation can be circumvented by utilizing the GHz-wide features of a Doppler broadened atomic gas. The anomalous dispersion of atomic vapours enables spectral filtering. These, so-called, Faraday anomalous dispersion optical filters (FADOFs) can be by far better than any commercial filter in terms of bandwidth, transition edge and peak transmission. We present a theoretical and experimental study on the transmission properties of a sodium vapour based FADOF with the aim to find the best combination of optical rotation and intrinsic loss. The relevant parameters, such as magnetic field, temperature, the related optical depth, and polarization state are discussed. The non-trivial interplay of these quantities defines the net performance of the filter. We determine analytically the optimal working conditions, such as transmission and the signal to background ratio and validate the results experimentally. We find a single global optimum for one specific optical path length of the filter. This can now be applied to spectroscopy, guide star applications, or sensing.

AB - Narrow-band optical filtering is required in many spectroscopy applications to suppress unwanted background light. One example is quantum communication where the fidelity is often limited by the performance of the optical filters. This limitation can be circumvented by utilizing the GHz-wide features of a Doppler broadened atomic gas. The anomalous dispersion of atomic vapours enables spectral filtering. These, so-called, Faraday anomalous dispersion optical filters (FADOFs) can be by far better than any commercial filter in terms of bandwidth, transition edge and peak transmission. We present a theoretical and experimental study on the transmission properties of a sodium vapour based FADOF with the aim to find the best combination of optical rotation and intrinsic loss. The relevant parameters, such as magnetic field, temperature, the related optical depth, and polarization state are discussed. The non-trivial interplay of these quantities defines the net performance of the filter. We determine analytically the optimal working conditions, such as transmission and the signal to background ratio and validate the results experimentally. We find a single global optimum for one specific optical path length of the filter. This can now be applied to spectroscopy, guide star applications, or sensing.

KW - Atmospheric optics

KW - Atom optics

KW - Atomic and molecular interactions with photons

M3 - Article

VL - 4

SP - 6552

JO - Scientific reports

JF - Scientific reports

SN - 2045-2322

ER -