A source of entangled photon-pairs: Optimizing emission in two quasi-phasematched crystals
2004 (English)In: Quantum Communication, Measurement And Computing / [ed] Barnett, SM; Andersson, E; Jeffers, J; Ohberg, P; Hirota, O, 2004, Vol. 734, 354-357 p.Conference paper (Refereed)
We extend our earlier results  of a bright source of non-degenerate polarization entangled photon-pairs by making a thorough theoretical and experimental investigation of its single-mode emission and state-decoherence. Using two perpendicular bulk crystals of periodically poled KTP, the source directly creates the polarization-entangled state (\HH> + \VV>)/root2 with signal and idler wavelengths of 810 nm and 1550 nm, respectively. In order to optimize the coupling into single-mode fiber we have developed a numerical algorithm which determines the emission mode and the fiber coupling efficiency for a given crystal length and focussing of the pump. For a 4.5 mm long crystal the optimal focussing of the pump is to a beam waist radius of 14 mum. With these focussing conditions the computer calculations give the lowest M-2 value for the emission mode, M-2 approximate to 3, and the best possible fiber coupling efficiency, gamma approximate to 75%. Using the theoretical results to optimize our experimental setup we obtained photon count rates of 1.4 MHz singles and 12 kHz coincidences, and visibilities H, V: 99.6% and 45degrees: 94.2%.
Place, publisher, year, edition, pages
2004. Vol. 734, 354-357 p.
, AIP Conference Proceedings, ISSN 0094-243X ; 734
IdentifiersURN: urn:nbn:se:kth:diva-44384ISI: 000226204400082ISBN: 0-7354-0216-7OAI: oai:DiVA.org:kth-44384DiVA: diva2:450575
7th International Conference on Quantum Communication, Measurement and Computing Location: Glasgow, Scotland, Date: JUL 25-29, 2004
QC 201110212011-10-212011-10-202011-10-21Bibliographically approved