摘要
由于TeO2声光偏转器(Acousto-optic deflector,AOD)具有超快的扫描速度、较宽的布拉格带宽以及大范围的偏转角度等优点,可以及时地改变光镊的位置,因此是获得无缺陷原子阵列的重要工具,在量子计算与模拟中具有重要的作用。但是,当声光偏转器输入含有多频率成分的信号时,会出现频率之间相互调制,导致衍射效率降低,出现不需要的衍射光且得到的衍射光强度分布不均匀等问题。基于此,对多个频率之间的相互调制过程进行了分析,通过对模型的计算分析得到了抑制频率互调的相位条件,并通过实验进行验证,再进行强度优化后得到强度分布相对均匀的光镊阵列。之后对互调过程进行仿真模拟,仿真结果显示与实验测量结果基本符合。对光镊阵列的参数测试显示,聚焦光镊的腰斑为1.5μm,现有实验光路可获得间距3μm的22×22的光镊阵列,满足中性原子阵列的实验需求。
Objective Acousto-optic deflector(AOD)is an optical diffraction device,which has the advantages of ultra-fast scanning speed,wide Bragg band and larger deflection range.When the control frequency is multi-tone it will produce several beams corresponding to each frequency.When the control frequency changes linearly,the diffracted beam will shift linearly,which is an effective method to make an arbitral structure of neutral atomic array.However,when the control frequency is multi-tone,there is an effect called frequency intermodulation effect that produces many unwanted diffracted beams and make the wanted beams'diffraction efficiency very low.This effect results in the nonuniform trap depth distribution of the optical array,and ultimately affecting the consistency of the atomic array.To overcome this,the principle that how frequency intermodulation is produced and how to suppress it has been analyzed in this paper.At last,we experimentally test the intermodulation impact and do the power spectrum simulation,which show that the proposed analysis meets the results very well.Methods This paper aims to analyse how the frequency intermodulation is produced and find a method to suppress it.First,we theoretically analyze the principle of frequency intermodulation.According to our analyses,we only need to eliminate the sum and difference frequency,then the frequency intermodulation can be suppressed greatly.This can be realized by giving different phases to different frequency.Here,we just give out the phases randomly several times,then get several sum and difference frequency results,where the minimum one corresponds to the best phases for intermodulation suppression.By this way,we simulate the intermodulation process and give out the optimized phases(Fig.1,Tab.1).After that,a signal with 10 frequencies(80-98 MHz with interval of 2 MHz)is divided into two to control two channels of the AOD and then tweezer intensity with and without phase optimization are measured(Fig.3).Finally,the power spectrums(Fig.5)with and without phase optimization are simulated,which fits very well with the experimental results(Fig.3).In addition,some parameters of optical tweezers are measured(Fig.6).Results and Discussions We take a 10×10 array as example,the intensity distribution before and after the phase optimization are measured.The result show that the standard deviation before and after the phase optimization are 0.7806 and 0.1005,respectively.And then the process is numerically simulated,the power spectrum result shows that the theoretical analysis can meet the experimental result very well when the interaction index k is 0.09.By adding the intensity equalization method,a 10×10 array with normal distribution has been realized.The key point is to cancell the sum and difference frequency by choosing the phase for each frequency.But the calculation need too much time,choosing random phase can suppress the intermodulation somehow according to our analysis.Conclusions According to our analyses and simulation,a 10×10 optical tweezer array with homogeneous intensity distribution has been achieved after phase optimization and intensity equalization feedback.The waist of each beam in the tweezer is measured about 1.5μm.For the light path we already have,a 22×22 array with site distance of about 3μm can be realized.The results can meet the requirement of neutral atomic array for quantum computation and simulation very well.
作者
王世珍
陈嘉怡
李东豪
徐忠孝
申恒
Wang Shizhen;Chen Jiayi;Li Donghao;Xu Zhongxiao(State Key Laboratory of Quantum Optics and Quantum Optics Devices,Institute of Opto-electronics,Shanxi University,Taiyuan 030006,China;Collaborative Innovation Center of Extreme Optics,Shanxi University,Taiyuan 030006,China)
出处
《红外与激光工程》
EI
CSCD
北大核心
2023年第7期166-172,共7页
Infrared and Laser Engineering
基金
国家自然科学基金项目(12222409,11974228,12204289)
国家重点研发计划青年项目(2020YFA0309400)
山西省科技重大专项计划“揭榜挂帅”项目。
关键词
光镊阵列
声光偏转器
频率互调
中性原子阵列
optical tweezer array
acousto-optic deflector
frequency intermodulation
neutral atom array
