Description
An experiment is being set up at the Centre for Advanced Laser Applications (CALA) in Garching near Munich to search for vacuum photon-photon scattering with a Petawatt class laser. Colliding two intense laser pulses with $\mathcal{O}(10^{20})$ photons each, results in a few ($<10$) photons scattering into the detector. The detection and characterization of this signal poses high requirements on the detector and the subsequent evaluation. Since the scattered photons are of the same wavelength as both driving pulses, the main challenge is to detect the few scattered photons with a background of thousands or more and the intrinsic shot noise thereof. Using an interferometric approach similar to optical homodyne detection enables an optically gated detection, which allows to overcome this challenge when combined with a sophisticated evaluation routine. In this contribution, the idea behind the detector setup and the evaluation routine are presented. Furthermore, the power and limitations of this approach are shown by the application to simulated data.
