The absolute frequency of 87Rb 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition at 778nm is measured in an accuracy of 44kHz. A home-made erbium-doped fiber laser frequency comb with frequency stability of 5.0 ...The absolute frequency of 87Rb 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition at 778nm is measured in an accuracy of 44kHz. A home-made erbium-doped fiber laser frequency comb with frequency stability of 5.0 × 10-13@1 s is employed for the light source. By using a periodically poled lithium niobate, the femtosecond pulse operating in 1556 nm is frequency-doubled to 778 nm to obtain the direct two-photon transition spectroscopy of thermal rubidium vapor. Through sweeping the carrier envelope offset frequency （fceo）, the 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition line is clearly resolved and its absolute frequency is determined via the peak-finding of the fitting curve. After the frequency correction, the measured result agrees well with the previous experiment on this transition. The entire potential candidate of optical frequency standard for system configuration is compact and robust, providing a telecommunication applications.展开更多
Highly stable frequency-controlled optical frequency combs axe key elements of many applications in time- frequency and optical-metrology domains. In this work, we demonstrate a highly stable frequency-controlled erbi...Highly stable frequency-controlled optical frequency combs axe key elements of many applications in time- frequency and optical-metrology domains. In this work, we demonstrate a highly stable frequency-controlled erbium-fiber-based optical frequency comb system. Its repetition rate is phase-stabilized to a continuous-wave laser with both an intra-cavity electro-optic modulator and a piezo-transducer; while the carrier-envelope-offset frequency is phase-locked to a radio-frequency signal generator by controlling the pump power. In-loop relative frequency stabilities of the comb are below 1 ×10-16 at I s, and integrate down to low 10-2o level at 104 s. The corresponding timing uncertainties are 100-200 as over the full measurement range.展开更多
Femtosecond enhancement cavity(fsEC) has been proved to be a powerful tool in a diverse range of applications.Here, we report the recent progresses in building an fsEC on kilowatt level average power, with the aim of ...Femtosecond enhancement cavity(fsEC) has been proved to be a powerful tool in a diverse range of applications.Here, we report the recent progresses in building an fsEC on kilowatt level average power, with the aim of realization of intracavity high harmonic generation(HHG) and extension of the wavelength of femtosecond optical frequency comb from infrared(IR) to extreme ultraviolet(XUV). Upon mode-matching optimization and cavity length locking, an intracavity average power of 6.08 kW is reached and the corresponding buildup is 225. After introducing noble gas of Xe into the focus region, clear sign of plasma has been observed. The generated HHG is also coupled out by a sapphire plate placed at Brewster's angle for the fundamental laser. Our work paves the way for the realization of an XUV comb.展开更多
介绍利用掺铒光学频率梳测量锶光钟频率的研究进展。整个测频系统由掺铒光纤光学频率梳和光谱展宽及拍频系统两部分组成。掺铒光学频率梳内的掺铒光纤飞秒激光器基于非线性偏振旋转机制实现锁模,其脉冲重复频率为232 MHz,腔内插入了能...介绍利用掺铒光学频率梳测量锶光钟频率的研究进展。整个测频系统由掺铒光纤光学频率梳和光谱展宽及拍频系统两部分组成。掺铒光学频率梳内的掺铒光纤飞秒激光器基于非线性偏振旋转机制实现锁模,其脉冲重复频率为232 MHz,腔内插入了能够快速控制重复频率的电光调制晶体。掺铒光学频率梳频率锁定后,重复频率和载波包络相移频率环内剩余噪声对稳定度的影响约1×10^(-16)@1s和2×10^(-20)@10~4s。光谱展宽部分利用高非线光纤和倍频晶体,将掺铒光学频率梳光谱范围由1 575 nm附近扩展到锶光钟波长(698.5 nm),在该波长处的光梳单模功率达1μW。将扩展后的掺铒光学频率梳光谱与单频激光拍频得到外差信号信噪比大于40 d B(分辨率带宽300 k Hz),满足后续锶光钟绝对频率测量的应用要求。展开更多
飞秒光学频率梳的出现使对未知激光的绝对频率测量成为可能,极大地简化了激光绝对频率的量值溯源和比对工作.为了保证测量数值的准确性,飞秒光学频率梳与未知激光的拍频信号fb的信噪比要求大于30 d B.针对碘稳频532 nm激光绝对频率测量...飞秒光学频率梳的出现使对未知激光的绝对频率测量成为可能,极大地简化了激光绝对频率的量值溯源和比对工作.为了保证测量数值的准确性,飞秒光学频率梳与未知激光的拍频信号fb的信噪比要求大于30 d B.针对碘稳频532 nm激光绝对频率测量的特定需求,以532 nm激光的基频光1064 nm激光的绝对频率测量为着眼点,本文采用303 MHz重复频率的掺Er光纤光学频率梳,首先通过激光放大和光谱展宽技术使光谱覆盖到1μm波段,然后采用级联掺Yb增益光纤技术,将扩谱后1μm波段的激光功率进行放大,提高了掺Er光纤光学频率梳扩谱后1μm波长附近的激光强度.采用碘稳频532 nm激光的基频光作为待测光源与飞秒光学频率梳进行拍频.实验表明,与未经过光谱增强的激光相比,光谱增强后的激光与1064 nm激光拍频信号的信噪比提高了5 d B,保持在35 d B附近.该技术有效地缓解了采用掺Er光纤光梳测量1064 nm激光绝对频率时对直接扩谱所获得的1μm波长激光的强度要求.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 61405002,91336103,10934010,61535001 and 61078026
文摘The absolute frequency of 87Rb 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition at 778nm is measured in an accuracy of 44kHz. A home-made erbium-doped fiber laser frequency comb with frequency stability of 5.0 × 10-13@1 s is employed for the light source. By using a periodically poled lithium niobate, the femtosecond pulse operating in 1556 nm is frequency-doubled to 778 nm to obtain the direct two-photon transition spectroscopy of thermal rubidium vapor. Through sweeping the carrier envelope offset frequency （fceo）, the 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition line is clearly resolved and its absolute frequency is determined via the peak-finding of the fitting curve. After the frequency correction, the measured result agrees well with the previous experiment on this transition. The entire potential candidate of optical frequency standard for system configuration is compact and robust, providing a telecommunication applications.
基金Supported by the National Natural Science Foundation of China under Grant Nos 91336101 and 61127901the West Light Foundation of the Chinese Academy of Sciences under Grant No 2013ZD02
文摘Highly stable frequency-controlled optical frequency combs axe key elements of many applications in time- frequency and optical-metrology domains. In this work, we demonstrate a highly stable frequency-controlled erbium-fiber-based optical frequency comb system. Its repetition rate is phase-stabilized to a continuous-wave laser with both an intra-cavity electro-optic modulator and a piezo-transducer; while the carrier-envelope-offset frequency is phase-locked to a radio-frequency signal generator by controlling the pump power. In-loop relative frequency stabilities of the comb are below 1 ×10-16 at I s, and integrate down to low 10-2o level at 104 s. The corresponding timing uncertainties are 100-200 as over the full measurement range.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11674356 and 11527807)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB21010400)
文摘Femtosecond enhancement cavity(fsEC) has been proved to be a powerful tool in a diverse range of applications.Here, we report the recent progresses in building an fsEC on kilowatt level average power, with the aim of realization of intracavity high harmonic generation(HHG) and extension of the wavelength of femtosecond optical frequency comb from infrared(IR) to extreme ultraviolet(XUV). Upon mode-matching optimization and cavity length locking, an intracavity average power of 6.08 kW is reached and the corresponding buildup is 225. After introducing noble gas of Xe into the focus region, clear sign of plasma has been observed. The generated HHG is also coupled out by a sapphire plate placed at Brewster's angle for the fundamental laser. Our work paves the way for the realization of an XUV comb.
文摘介绍利用掺铒光学频率梳测量锶光钟频率的研究进展。整个测频系统由掺铒光纤光学频率梳和光谱展宽及拍频系统两部分组成。掺铒光学频率梳内的掺铒光纤飞秒激光器基于非线性偏振旋转机制实现锁模,其脉冲重复频率为232 MHz,腔内插入了能够快速控制重复频率的电光调制晶体。掺铒光学频率梳频率锁定后,重复频率和载波包络相移频率环内剩余噪声对稳定度的影响约1×10^(-16)@1s和2×10^(-20)@10~4s。光谱展宽部分利用高非线光纤和倍频晶体,将掺铒光学频率梳光谱范围由1 575 nm附近扩展到锶光钟波长(698.5 nm),在该波长处的光梳单模功率达1μW。将扩展后的掺铒光学频率梳光谱与单频激光拍频得到外差信号信噪比大于40 d B(分辨率带宽300 k Hz),满足后续锶光钟绝对频率测量的应用要求。
文摘飞秒光学频率梳的出现使对未知激光的绝对频率测量成为可能,极大地简化了激光绝对频率的量值溯源和比对工作.为了保证测量数值的准确性,飞秒光学频率梳与未知激光的拍频信号fb的信噪比要求大于30 d B.针对碘稳频532 nm激光绝对频率测量的特定需求,以532 nm激光的基频光1064 nm激光的绝对频率测量为着眼点,本文采用303 MHz重复频率的掺Er光纤光学频率梳,首先通过激光放大和光谱展宽技术使光谱覆盖到1μm波段,然后采用级联掺Yb增益光纤技术,将扩谱后1μm波段的激光功率进行放大,提高了掺Er光纤光学频率梳扩谱后1μm波长附近的激光强度.采用碘稳频532 nm激光的基频光作为待测光源与飞秒光学频率梳进行拍频.实验表明,与未经过光谱增强的激光相比,光谱增强后的激光与1064 nm激光拍频信号的信噪比提高了5 d B,保持在35 d B附近.该技术有效地缓解了采用掺Er光纤光梳测量1064 nm激光绝对频率时对直接扩谱所获得的1μm波长激光的强度要求.
