Ultra-broadband SPDC for spectrally far separated photon pairs
Abstract
Generating photon pairs via spontaneous parametric down-conversion (SPDC) in nonlinear crystals is important for a wide range of quantum optics experiments with spectral properties such as their bandwidths often being a crucial concern. Here, we show the generic existence of particular phase-matching conditions in quasi-phase matched KTP, MgO:LN and SLT crystals that lead to ultra-broadband, widely non-degenerate photon pairs. It is based on the existence of group-velocity matched, far apart wavelength pairs and for 2 mm long crystals results in SPDC bandwidths between 15 and 25 THz (FWHM) for photon pairs with the idler photon in the technologically relevant mid-IR range 3-5 {\mu}m and the signal photon in the NIR below 1100 nm. We experimentally demonstrate this type of broadband phase-matching in ppKTP crystals for photon pairs centered at 800 nm and 3800 nm and measure a bandwidth of 15 THz. This novel method of generating broadband photon-pairs will be highly beneficial for SPDC-based imaging, spectroscopy, refractometry and OCT with undetected mid-IR photons.
- Publication:
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Optics Letters
- Pub Date:
- October 2019
- DOI:
- 10.1364/OL.44.004638
- arXiv:
- arXiv:1907.05959
- Bibcode:
- 2019OptL...44.4638V
- Keywords:
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- Quantum Physics;
- Physics - Optics
- E-Print:
- References added