title: Interferometric autocorrelation in the ultraviolet utilizing spontaneous parametric down-conversion inside an enhancement cavity.
abstract: Autocorrelation is a common method to estimate the duration of ultrashort laser pulses. In the ultraviolet (UV) regime it is challenging to employ the process of second-harmonic generation, most prominently due to absorption in nonlinear crystals at very short wavelengths. Here we show how to utilize spontaneous parametric down-conversion (SPDC) to generate an autocorrelation signal in the infrared (IR) for UV pulses. Our method utilizes the nth-order emission of the SPDC process, which occurs for low pumping powers proportional to the nth power of the UV intensity. Thus, counting 2n down-converted photons directly yields the nth-order autocorrelation. The method, now with detection of near-IR photons, is applied to the first direct measurement of ultrashort UV pulses circulating inside a UV enhancement cavity.
authors.affiliation: Max-Planck-Institut für Quantenoptik, Garching, Germany. p.michelberger1@physics.ox.ac.uk
authors.forename: P
authors.initials: P
authors.lastname: Michelberger
authors.forename: R
authors.initials: R
authors.lastname: Krischek
authors.forename: W
authors.initials: W
authors.lastname: Wieczorek
authors.forename: A
authors.initials: A
authors.lastname: Ozawa
authors.forename: H
authors.initials: H
authors.lastname: Weinfurter
mesh_terms: D000465:Algorithms; D007259:Infrared Rays; D007368:Interferometry / Q000379:methods; D007834:Lasers; D017785:Photons; D014466:Ultraviolet Rays