Measuring optical nonlinearities with pump-probe intracavity phase spectroscopy

Ethan Clements, Preston Ross, Anthony Rapp +6 more

Dariya Salykina, Stepan N. Balybin, Farid Ya Khalili

In the work by Balybin et al. [Phys. Rev. A 108, 053708 (2023)], the scheme of quantum nondemolition measurement of optical quanta that uses a resonantly enhanced Kerr nonlinearity in the optical microresonator, presqueezing of the probe beam, and its parametric amplification before the detection was analyzed theoretically. It was shown that the main factor that limits the sensitivity of the considered scheme is the interplay of optical losses and the nonlinear self-phase modulation (SPM) effect. Here we show that using the intracavity squeezing of the probe beam in this scheme, it is possible to cancel out the SPM effect. In this case, the sensitivity will be limited only by the available power in the pump beam and by the input/output losses in the signal beam. Our estimates show that using the best optical microresonators currently available, the sensitivity for the intracavity photon number approaching the single-photon one can be achieved. Therefore, this scheme could be of interest for optical quantum information processing tasks.

F. Hache, Philippe Roussignol, D. Ricard +1 more

Alexander M. McKillop, Marissa L. Weichman

Nonlinear spectroscopy is widely used to study the transient dynamics of molecules under strong light-matter coupling, though it remains unclear to what extent uncoupled intracavity molecules obscure signals from the strongly-coupled species of interest. Pump or probe fields resonant in the strongly-coupled spectral region will preferentially interact with cavity-coupled molecules, but can exhibit severe optical artifacts due to wave interference in the cavity. On the other hand, non-resonant pump or probe fields having wavelengths at which the cavity mirrors are highly transmissive propagate as traveling waves along the cavity axis, interacting with both coupled and uncoupled intracavity molecules. Here, we quantify the contributions of signals from strongly-coupled and uncoupled populations in simulated experiments with different resonant and non-resonant pump-probe configurations. We find that while resonant schemes maximize selectivity for the signals of strongly-coupled molecules, non-resonant schemes retain surprisingly high sensitivity to these signals while remaining less susceptible to optical artifacts.

Surajit Dhara

Stephen J. Smith, Daniel S. Elliott