Based on the theory of quantum optics, an analogue of the Autler-Townes splitting (ATS) system is realized by coupling a Fabry-Pérot (FP) microcavity and a long-period fiber grating via the photonic tunneling effect. The stationary equations of the intracavity field amplitudes indicate that the splitting modes can be tuned by controlling the resonance frequency of the device. We demonstrated the feasibility of this theoretical result by adjusting the microcavity mirror offset Δx in the experiments. Both the theoretical analysis and the experimental results show that the transmission spectrum is remarkably adjustable due to the tunable ATS effect. The splitting modes of the developed device allow for an extra degree of freedom to respond to the sensing signal, which is important for ultra-sensitive sensing. The refractive index is accurately adjustable, providing for potential phase matching applications. In addition, the device can serve as either an ATS system or an FP cavity.
Based on the theory of quantum optics, an analogue of the Autler-Townes splitting (ATS) system is realized by coupling a Fabry-Pérot (FP) microcavity and a long-period fiber grating via the photonic tunneling effect. The stationary equations of the intracavity field amplitudes indicate that the splitting modes can be tuned by controlling the resonance frequency of the device. We demonstrated the feasibility of this theoretical result by adjusting the microcavity mirror offset Δx in the experiments. Both the theoretical analysis and the experimental results show that the transmission spectrum is remarkably adjustable due to the tunable ATS effect. The splitting modes of the developed device allow for an extra degree of freedom to respond to the sensing signal, which is important for ultra-sensitive sensing. The refractive index is accurately adjustable, providing for potential phase matching applications. In addition, the device can serve as either an ATS system or an FP cavity.
In this paper, we experimentally demonstrated an Autler-Townes splitting (ATS) effect in a cascaded optical whispering gallery mode resonator system. Although electromagnetically induced transparency (EIT) has been investigated as an interesting Fano resonance in the recent decades, the critical resonance matched condition of a high quality factor resonator and a low-quality factor resonator makes EIT difficult to realize and hardly tunable. In contrast, ATS requires relatively simple system configurations, and the effect can be preserved over a large tuning range. In our approach, a theoretical model based on coupled mode theory is developed, and the methodology of creating and controlling the ATS modes is demonstrated. In our experiment, the optical resonators have a loaded quality factor of about 3 × 105and cascaded in a strong coupling condition. For the experimental demonstration, a thermo-optical mechanism is utilized to control the splitting modes in our system. The asymmetric shape of a splitting resonances shift has a perfect fit with the theoretical calculations and numerical modeling results. Utilizing the precise tenability of splitting modes, the ATS has an extra degree of freedom to perform resonance tuning, which has become an ideal method to overcome the current detection limit.
We report a novel, to the best of our knowledge, way to achieve phase-controlled dual-wavelength resonance based on whispering-gallery-mode (WGM) microcavities experimentally. With the help of a feedback waveguide, not only two optical pathways but also a unidirectional coupling between counter-propagating waves are formed, which is the requirement of all-optical analogues of electromagnetically induced transparency and Autler-Townes splitting. By adjusting the accumulating phase introduced from the fiber waveguide, we observe the signal lineshape changes from symmetric to asymmetric, i.e., the resonant transmission and extinction ratio of two splitting modes can be controlled, which brings a new degree of freedom to the WGM resonator system. These results may boost the development of quantum state control and pave the way for reconfiguring devices such as narrow-band filters.
Whispering gallery mode optical microresonators represent a promising avenue for realizing optical analogs of coherent light–atom interactions, circumventing experimental complexities. All-optical analogs of Autler–Townes splitting have been widely demonstrated, harnessing coupled optical microresonators, also known as photonic molecules, wherein the strong coupling between resonant fields enables energy level splitting. Here, we report the characterizations of Autler–Townes splitting in waveguide-coupled microring dimers featuring mismatched sizes. By exploiting backscattering-induced coupling via Rayleigh and Mie scatterers in individual rings, high-order Autler–Townes splitting has been realized, yielding supermode hybridization in a multi-level system. Upon resonance detuning using an integrated phase shifter, intra-cavity coupling-induced splitting becomes almost indistinguishable at the zero-detuning point where the strong inter-cavity coupling counteracts the imbalance of backscattering strengths in individual rings. Through demonstrations on the maturing silicon photonics platform, our findings establish a framework of electrically tunable photonic molecules for coupling-mediated Autler–Townes splitting, offering promising prospects for on-chip signal generation and processing across classical and quantum regimes.
Quantum interference effects in the unmodulated quantum systems with light-matter interaction have been widely studied, such as electromagnetically induced transparency (EIT) and Autler-Townes splitting (ATS). However, the similar quantum interference effects in the Floquet systems (i.e., periodically modulated systems), which might cover rich new physics, were rarely studied. In this article, we investigate the quantum interference effects in the Floquet two- and three-level systems analytically and numerically. We show a coherent destruction tunneling effect in a lotuslike multipeak spectrum with a Floquet two-level system, where the intensity of the probe field is periodically modulated with a square-wave sequence. We demonstrate that the multipeak split into multiple transparency windows with tunable quantum interference if the Floquet system is asynchronously controlled via a third level. Based on phenomenological analysis with Akaike information criterion, we show that the symmetric central transparency window has a similar mechanism to the traditional ATS or EIT depending on the choice of parameters, additional with an extra degree of freedom to control the quantum interference provided by the modulation period. The other transparent windows are shown to be asymmetric, different from the traditional ATS and EIT windows. These nontrivial quantum interference effects open up a scope to explore the applications of the Floquet systems.
Fiber Fabry–Perot cavities, formed by micro-machined mirrors on the end-facets of optical fibers, are used in an increasing number of technical and scientific applications, where they typically require precise stabilization of their optical resonances. Here, we study two different approaches to construct fiber Fabry–Perot resonators and stabilize their length for experiments in cavity quantum electrodynamics with neutral atoms. A piezo-mechanically actuated cavity with feedback based on the Pound–Drever–Hall locking technique is compared to a novel rigid cavity design that makes use of the high passive stability of a monolithic cavity spacer and employs thermal self-locking and external temperature tuning. Furthermore, we present a general analysis of the mode matching problem in fiber Fabry–Perot cavities, which explains the asymmetry in their reflective line shapes and has important implications for the optimal alignment of the fiber resonators. Finally, we discuss the issue of fiber-generated background photons. We expect that our results contribute toward the integration of high-finesse fiber Fabry–Perot cavities into compact and robust quantum-enabled devices in the future.
The interaction of light and matter in a microcavity depends crucially on the position of the emitter in the spatial field distribution of the resonator mode. In an ideal experiment one would like to place an emitter at will within the mode of the cavity to change the interaction strength in a controllable fashion. Although several efforts have aimed at the realization of such a scheme, its application remains an experimental challenge. Fabry-Perot microresonators constitute a promising route for a controlled coupling of atoms in the gas phase as well as for solid state systems and molecules. Here we present the selective coupling of fluorescent nanoparticles and single molecules to a tunable, fiber-based, scannable microcavity.