title: Note: An ultranarrow bandpass filter system for single-photon experiments in quantum optics.
abstract: We describe a combined ultranarrow bandpass filtering setup for single-photon experiments in quantum optics. The filter is particularly suitable for single-photon electromagnetically induced transparency (EIT) experiments, but can also be used in several similar applications. A multipass planar Fabry-Perot etalon together with polarization filters and spatial filtering allows 114 dB pump beam suppression, while the signal beam is attenuated by just 4 dB, although both wavelengths are only separated by 0.025 nm (9.2 GHz). The multipass etalon alone accounts for 46 dB suppression while it has a peak transmission of 65%. We demonstrate EIT experiments in Cs vapor at room temperature with probe power in the femtowatt regime using this filter.
authors.affiliation: Nano Optics, Institute of Physics, Humboldt-Universität zu Berlin, Hausvogteiplatz 5-7, 10117 Berlin, Germany. david.hoeckel@physik.hu-berlin.de
authors.forename: David
authors.initials: D
authors.lastname: Höckel
authors.forename: Eugen
authors.initials: E
authors.lastname: Martin
authors.forename: Oliver
authors.initials: O
authors.lastname: Benson