Optimized multiphoton absorption measurements in nonlinear interferometers*

In nonlinear interferometers, the passive beam splitters of linear interferometers are replaced by optical parametric amplifiers (OPA). These nonlinear interferometers have been utilized for applications such as sensing, enhancing the resolution in imaging and spectroscopy [1]. In our study, we investigate the precision of the cross-section measurements of multiphoton absorption with a nonlinear interferometer. In our setup, a multiphoton absorbing sample is placed between two OPAs which are used to (un)squeeze an input state of light. We devise a strategy in which a massive enhancement in the precision of the cross-section measurements at large photon numbers compared to the classical measurements can be obtained [2]. This enhancement is realized by the optimization of the properties of the light fields inside the interferometer. The enhancement is robust against some experimental imperfections and enables the detection of multiphoton absorption at significantly lower excitation intensities compared to classical methods.

[1] M. V. Chekhova and Z. Y. Ou, Adv. Opt. Photon. 8, 104 (2016).

[2] S. Panahiyan, C. S. Muñoz, M. V. Chekhova, F. Schlawin, [arXiv:2209.02697].