Enhanced Free Space Beam Capture by Improved Optical Tapers

Bartley T., Heim B., Elser D., Sych D., Sabuncu M. H., Wittmann C., ...More

1st International Conference of Quantum Communication and Quantum Networking, Naples, Italy, 26 - 30 October 2009, vol.36, pp.100-107 identifier

  • Publication Type: Conference Paper / Full Text
  • Volume: 36
  • City: Naples
  • Country: Italy
  • Page Numbers: pp.100-107
  • Keywords: Optical taper, free space communication, beam-jitter, atmospheric optics, random media, quantum key distribution, QUANTUM KEY DISTRIBUTION, SECURITY
  • Dokuz Eylül University Affiliated: Yes


In our continuous variable quantum key distribution (QKD) scheme, the homodyne detection set-up requires balancing the intensity of an incident beam between two photodiodes. Realistic lens systems are insufficient to provide a spatially stable focus in the presence of large spatial beam-jitter caused by atmospheric transmission. We therefore present an improved geometry for optical tapers which offer up to four times the angular tolerance of a lens. The effective area of a photodiode can thus be increased, without decreasing its bandwidth. This makes them suitable for use in our free space QKD experiment and in free space optical communication in general.