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Optics Letters

Beamlike twin-photon generation by use of type II parametric downconversion

Shigeki Takeuchi

Published Jun 1, 2001• 105 citations
Publisher

Abstract

Beamlike twin-photon generation by use of type II spontaneous parametric downconversion is demonstrated. The intensity distribution of each beam is round, and the emission angle is very small (0.9 degrees ). As a result, a high coincidence-count rate per unit of pump power was recorded. The ratio of coincidence-count rate to single-count rate was estimated to be 80% in this experiment. These features suggest that this method is useful for generation of a single-photon state and is applicable to bright, entangled twin-photon sources.

DOI
10.1364/ol.26.000843

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Beamlike twin-photon generation by use of type II spontaneous parametric downconversion is demonstrated. The intensity distribution of each beam is round, and the emission angle is very small (0.9 degrees ). As a result, a high coincidence-count rate per unit of pump power was recorded. The ratio of coincidence-count rate to single-count rate was estimated to be 80% in this experiment. These features suggest that this method is useful for generation of a single-photon state and is applicable to bright, entangled twin-photon sources.
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The method allowing enhance the eficiency of entangled photon sources based on Type II spontaneous parametric down conversion (SPDC) by means of mode inversion of one of the SPDC output beams is described. Overlap between the the entire signal in idler beams can be achieved using the mode inversion thus maximizing the SPDC photon pair yields. With this method, coincidence count rates as high as 60 kHz from a single 0.5 mm long bulk BBO crystal pumped by the second-harmonic radiation of a femtosecond Ti: Sapphire laser, were obtained.