Ultranarrow bandwidth spectral filtering for long-range free-space quantum key distribution at daytime.
We describe a Fabry-Perot-based spectral filter for free-space quantum key distribution (QKD). A multipass etalon filter was built, and its performance was studied. The whole filter setup was carefully optimized to add less than 2 dB attenuation to a signal beam but block stray light by 21 dB. Simulations show that such a filter might be sufficient to allow QKD satellite downlinks during daytime with the current technology.
Nano Optics, Institute of Physics, Humboldt-Universität zu Berlin, Hausvogteiplatz 5-7, 10117 Berlin, Germany. david.hoeckel@physik.hu-berlin.de
David
D
Höckel
Lars
L
Koch
Eugen
E
Martin
Oliver
O
Benson