摘要
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。
We demonstrate a home-made erbium-doped-fiber optical frequency comb for frequencymeasurement of Strontium optical clock. The mode-locked laser is based on nonlinear-polarization-rotation （NPR）mechanism with a repetition rate of 232 MHz. An intra-cavity electro-optic modulator is used to stabilize therepetition rate for tight frequency control. In-loop frequency instabilities of the carrier envelope offset andrepetition rate are about 1 ？ 10-16at 1 second and integrate down to low 10-20level at 104seconds. By using highly nonlinear fiber and MgO： Periodically poled lithium niobate, optical spectrum is broadened from infrared1 575 nm to 698.5 nm with a power density of about 1 μW/mode. Spectrum of beatnote between a 698.5 nm CWlaser （i.e. the Sr clock laser） and the comb shows a signal-to-noise ratio （SNR） of about 40 dB with 300 kHzmeasurement bandwidth.
出处
《时间频率学报》
CSCD
2017年第3期129-136,共8页
Journal of Time and Frequency
基金
国家自然科学基金资助项目(91336101
61127901)
中国科学院"西部之光"人才培养计划重点资助项目(2013ZD02)
关键词
掺铒光纤
光学频率梳
频谱扩展
频率测量
erbium-doped fiber
optical frequency combs
frequency broaden
frequency measurement
