Experimental Research On The Acousto-optic Modulator In The Polarization-maintaining Transmission Of Quantum States

With the rise and development of laser technology and optoelectronic technology,acousto-optic modulator has become an important device in many fields.In the new field of quantum communication,acousto-optic modulator can usually realize the functions of optical switch,timing control,special optical switch,entangled photon feedback acquisition responder,etc.Acousto-optic diffraction efficiency and the ability to maintain the polarization of arbitrarily polarized light are two important performance indexes of acousto-optic modulator,and both of them have a significant impact on the experimental results of quantum optics.In this paper,the study of acousto-optic modulator starts from understanding acousto-optic effect.Firstly,the structure and working principle of the acousto-optic modulator are introduced,and various performance parameters of the acousto-optic modulator are analyzed,especially the diffraction efficiency parameter is further analyzed and experimentally studied,and the existing methods to improve the diffraction efficiency are summarized.On this basis,an acousto-optic diffraction efficiency enhancement system with arbitrarily polarized light is designed to improve the diffraction efficiency of the acousto-optic modulator and achieve arbitrarily polarized light polarization preservation.In this system,the acousto-optical diffraction efficiency is improved by 0 order diffraction light feedback method.At the same time,a wave plate group composed of1/4 wave plate,1/2 wave plate and 1/4 wave plate is used for phase compensation so as to realize the polarization preservation of arbitrarily polarized light.The experimental results show that the system can significantly improve the diffraction efficiency of the acousto-optic modulator and ensure the polarization preserving transmission of arbitrary polarized light in the field of quantum communication.This work provides a theoretical and experimental basis for the future research of optical fiber coupled acousto-optic modulator and quantum devices based on acousto-optic modulator.The modified acousto-optic modulation system is applied to a quantum storage experiment based on the cold atom ensemble,and the signal photons released by the experiment are measured.The measured data is processed by a program with quantum process tomography as the core technology to obtain the fidelity of the experimental quantum.The results show that the polarization-preserving ability of the modified acousto-optic modulation system satisfies the requirement of the quantum optical path of polarization entanglement at the single photon level.This work provides an experimental basis for future experiments and applications in the field of quantum communication.