Polarization dependence on downconversion emission angle: investigation of the ‘Migdall effect’
Radhika Rangarajan, Alfred B. U’Ren, Paul G. Kwiat · Journal of Modern Optics · 2010
Photonic sources based on spontaneous parametric downconversion (SPDC) are now pervasively employed in optical quantum information processing protocols. The recent focus on engineering efficient photonic sources requires a thorough understanding of several of the subtler characteristics of SPDC, which had previously been negligible. Here, we experimentally investigate one such phenomenon – the dependence of the downconversion polarization on emission angle. Additionally, we discuss the significance of this effect from the perspective of better engineering SPDC sources. We also propose techniques, specifically in the context of a two-crystal scheme for generating polarization-entangled photons, to exploit the effect and drastically improve source quality in certain limiting cases.