采用泵浦-探测法测量两机械振子间的耦合强度  

Measurement of the Coupling Strength between Two Mechanical Resonators by Pump-Probe Method

作　　者：何勇[1] 陈奇 HE Yong;CHEN Qi(School of Microelectronics and Control Engineering,Changzhou University,Changzhou 213164 China)

机构地区：[1]常州大学微电子与控制工程学院,江苏常州213164

出　　处：《量子光学学报》2024年第3期19-26,共8页Journal of Quantum Optics

摘　　要：两机械振子间的耦合可用来实现非厄米系统的宇称-时间(parity-time,PT)对称现象。为了测量耦合强度值,我们借助一个光学腔,让它与其中一个机械振子通过光学辐射压产生耦合。我们采用泵浦-探测法测量两机械振子间的耦合强度。整个系统在强的泵浦场和弱的探测场共同驱动下,其透射谱上会出现两个透明窗口。每个透明窗口是由光力学诱导透明效应产生的。结果显示,两透明窗口峰间的频率间隔是耦合强度的2倍。我们通过透明窗口间的频率间隔可获得机械耦合强度。最后,我们考虑了透明窗口的半宽对测量精度的影响,展示了在较小的泵浦功率下,透明窗口的半宽较小,以致机械耦合强度的测量精度可达0.2kHz。Objective The coupling between two mechanical resonators has a wide range of applications in physics,such as realizing the phenomenon of parity-time(PT)symmetry in non-Hermitian systems and enabling coherent manipulation of phonons.In order to study these phenomena in depth,it is crucial to measure their coupling strength.This study aims to propose a method to accurately measure the coupling strength between two mechanical resonators,which provides a basis for further research and applications.Method In a system of two coupled mechanical resonators,we employ an optical cavity coupled to one of the mechanical resonators via optical radiation pressure and drive the optical cavity with a strong pump field and a weak probe field.By using this pump-probe method,we measure the frequency interval between the two transparent windows induced by the mechanical eigenmodes in the transmission spectrum of the system's probe field to calculate the coupling strength.Result and Discussions Theoretical results show two transparent windows that are caused by optomechanically induced transparency appear in the transmission spectrum of the system's probe field.In principle,the frequency positions of the two transparent windows correspond to the frequencies of both mechanical eigenmodes,which can be interpreted in terms of energy level diagrams with their interval between peaks being twice the coupling strength.The actual measurements also consider the effect of the half-width of the transparent windows on the measurement accuracy.The results show that using a lower pump power results in a smaller half-width of the transparent windows,enabling the measurement precision of the mechanical coupling strength to be 0.2 kHz.Conclusion In summary,the coupling strength between two mechanical resonators is measured by the pump-probe method in this paper.The whole system is driven by a strong pump field and a weak probe field together,and two transparent windows appear in the system's transmission spectrum.The value of the coupling strength is

关 键 词：腔光力学系统 光力诱导透明 机械振子间的耦合强度 泵浦-探测法 测量精度 

分 类 号：O437[机械工程—光学工程]