Nonlinear excitations in a quantum dimer

Marcis P. Auzinsh

S. Raghavan

G. P. Berman

Yao Zhou, Zihao Chen, Lihong V. Wang +1 more

In this Letter, we show that photonic dimers, the quantum mechanical bound states of two photons, enable efficient nonlinear two-photon excitation, primarily due to the Lorentzian energy anti-correlation and to the temporal proximity between the constituent photons. We analytically and numerically demonstrate the order-of-magnitude improvement of the excitation efficiency per photon by the photonic dimers over the ultrashort pulses from a laser. We further show that, owing to the high excitation efficiency, the two-photon transition rate by photonic dimers deviates from the well-known linear intensity dependence at low intensities. Possible approaches for generating the photonic dimers in semiconductor platforms are also investigated.

Deniz Türkpençe, Alpan Bek, Mehmet Emre Taşgın

We show that, nonlinear optical processes in a plasmonic metal nanoparticle (MNP) dimer can be controlled by the presence of a molecule or a quantum dot. (i) Frequency conversion can be suppressed if the dimer is coupled to a quantum object which is resonant to the generated frequency. This occurs simply because, EIT does not allow an excitation at the converted frequency frequency. (ii) On the contrary, a similar effect can be used to enhance the frequency conversion. Nonlinear processes can be brought to resonance without tuning the dimer modes. Path interference effect cancels the nonresonant frequency terms. Here, we consider the second harmonic generation (SHG) as an example to demonstrate the control mechanism. However, the method can be easily generalized to other nonlinear processes.

Edward Shuryak