摘要
介绍了一种用于里德伯原子激发的纳秒脉冲激光系统.实验利用两个kHz线宽的1018 nm连续激光器作为种子源,通过两个20GHz带宽的光纤调制器产生时间分离的脉冲激光;脉冲激光经掺镱光纤放大器后输出峰值功率约4600 W,单次穿过PPLN(周期极化铌酸锂)晶体倍频获得509 nm脉冲激光,典型脉冲激光峰值功率约173W.该激光系统单路输出脉冲重复频率在300 kHz-100 MHz范围连续可调,脉宽在1-100 ns范围连续可调.该509 nm激光在聚焦条件下可以实现GHz带宽的铯原子里德伯态激发.
Single photon source is a non-classical light field with anti-bunching effect,which has a potential applications in the research of fundamental physics problems,quantum precision measurement,quantum communication,quantum computing,etc.The strong interaction between highly excited Rydberg atoms presents an excitation blockade effect.In a dense Rydberg atomic ensemble,the excitation of more than one Rydberg atom within a blockade volume is suppressed,where the interactions of Rydberg atoms shift the atomic states out of resonance with an excitation laser.We consider here the generation of single photon source by using a four-wave mixing scheme in a room-temperature atomic vapor cell.In a homemade micrometer-sized atomic vapor cell,one-dimensional size is smaller than the radius of Rydberg blockade and the other two-dimensional size is limited by the size of focused laser beam.The blockade radius is on the order of a few micrometers,depending on the Rydberg atom states.An excitation blockade effect can be used to realize single photon source in thermal cesium vapor microcells.The micron cesium-cell is used to spatially localize atomic groups,which results in the atomic decoherence time on the order of microseconds or even nanoseconds.This requires a high-power pulsed laser to prepare the Rydberg atomic state at a nanosecond scale.Four-photon excitation schemes with narrow linewidth lasers are also used experimentally.The cesium-Rydberg state can usually be excited by the lasers with optical wavelengths 852 and 509 nm,respectively.The laser system is well-stabilized so that the detuning is small compared with the spontaneous linewidth of Rydberg state,while the laser power and temporal mode need to be specified for ns-time coherence in thermal cesium vapor microcells.The 852 nm laser can be achieved by modulating the continuous laser beam with the help of an electro-optic intensity modulator(EOIM).While this remains a technical challenge for 509 nm laser with ns-laser pulse.There is no EOIM to generate the ns-laser pulse with high power.We demonstrate a novel generation method of 509 nm laser system.In our experiments,a 1018 nm fiber laser is used to produce a continuous laser with a typical linewidth of~8 kHz and power of 10 mW.The nanosecond pulse is generated with the help of an electro-optic intensity modulator(EOIM)by modifying the continuous laser beam.The peak power of modulated optical pulse is amplified to 4600 W by using a homemade fiber amplifier.The output beam of 1018 nm is then injected into a periodically poled lithium-niobate(PPLN)to generate the second harmonics laser of 509 nm.The typical peak power of 509 nm reaches 173 W by optimizing PPLN phase matching parameters.The pulse repetition frequency of the 509 nm laser can be continuously tuned in a range of 300 kHz-100 MHz,and the pulse width can be continuously tuned in a range of 1-100 ns.Peak power fluctuation of the pulses is about 1.3%.The power 509 nm laser with optimized pulse parameters can be used to excite the cesium atom with GHz bandwidth.Meanwhile the two seed source lasers is well established experimentally,which allows alternating pulses with a different wavelength.This is an essential capability for realizing a single photon source through four-wave mixing.
作者
刘瑶
何军
苏楠
蔡婷
刘智慧
刁文婷
王军民
Liu Yao;He Jun;Su Nan;Cai Ting;Liu Zhi-Hui;Diao Wen-Ting;Wang Jun-Min(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;National Key Laboratory of Science and Technology on Space Microwave,China Academy of Space Technology(Xi’an),Xi’an 710000,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2023年第6期38-43,共6页
Acta Physica Sinica
基金
国家重点研发计划(批准号:2021YFA1402002)
国家自然科学基金(批准号:61875111,62071376)
山西省“1331工程”重点项目资助的课题.
关键词
里德伯原子
脉冲激光器
非线性频率转换
单光子源
Rydberg atom
pulse laser
nonlinear frequency conversion
single photon source
