General Theoretical Model for Resonantly Enhanced Optical Modulators

Popović

Zhengyi Wan, Qizhuang Cen, Yuedi Ding +6 more

Ring resonators play a crucial role in optical communication and quantum technology applications. However, these devices lack a simple and intuitive theoretical model to describe their electro-optical modulation. When the resonance frequency is rapidly modulated, the filtering and modulation within a ring resonator become physically intertwined, making it difficult to analyze the complex physical processes involved. We address this by proposing an analytical solution for electro-optic ring modulators based on the concept of a "virtual state." This approach equates a lightwave passing through a dynamic ring modulator to one excited to a virtual state by a cumulative phase and then returning to the real state after exiting the static ring. Our model simplifies the independent analysis of the intertwined physical processes, enhancing its versatility in analyzing various incident signals and modulation formats. Experimental results, including resonant and detuning modulation, align with the numerical simulation of our model. Notably, our findings indicate that the dynamic modulation of the ring resonator under detuning driving approximates phase modulation.

Xinxin Hu, Changling Zhao, Zhu-Bo Wang +6 more

Cavity-enhanced optical controlling is experimentally observed with a low-control laser power in a cavity-atom ensemble system. Here, the three-level atoms are coupled with two optical modes of a Fabry-Perot cavity, where a new theoretical model is developed to describe the effective three-wave mixing process between spin-wave and optical modes. By adjusting either temperature or cavity length, we demonstrate the precise frequency tuning of the hybrid optical-atomic resonances. When the doubly-resonant condition is satisfied, the probe laser can be easily modulated by a control laser. In addition, interesting non-Hermitian physics are predicted theoretically and demonstrated experimentally, and all-optical switching is also achieved. Such a doubly-resonant cavity-atom ensemble system without a specially designed cavity can be used for future applications, such as optical signal storage and microwave-to-optical frequency conversion.

A.G. Tam, Kerry James Hinton, Peter M. Farrell +1 more

Eugene A. Tsygankov, Sergey Petropavlovsky, Maria I. Vaskovskaya +3 more

Motivated by recent developments in atomic frequency standards employing the effect of coherent population trapping (CPT), we propose a theoretical framework for the frequency modulation spectroscopy of the CPT resonances. Under realistic assumptions we provide simple yet non-trivial analytical formulae for the major spectroscopic signals such as the CPT resonance line and the in-phase/quadrature responses. We discuss the influence of the light shift and, in particular, derive a simple expression for the displacement of the resonance as a function of modulation index. The performance of the model is checked against numerical simulations, the agreement is good to perfect. The obtained results can be used in more general models accounting for light absorption in the thick optical medium.

R. Mark Wilson