2.16m望远镜高分辨率光谱仪的天文光学频率梳

Astronomical Laser Frequency Comb for High Resolution Spectrograph of a 2.16-m Telescope

介绍了应用于我国兴隆观测站2.16m望远镜高分辨率光谱仪的天文光学频率梳。采用掺镱光纤激光频率梳作为源光梳,通过模式滤波使模式间隔达到25GHz,与天文光谱仪的分辨率相匹配。光谱展宽和平滑后,光谱覆盖可见光范围达到270nm以上,光谱平滑度可长期保持在1dB范围内,边模抑制比达到42dB。该天文光学频率梳的视向速度理论定标精度可达cm/s量级,使寻找系外类地行星乃至直接测量宇宙膨胀速度成为可能。

An astronomical laser frequency comb（astro-comb）,which will be applied as a calibrator on the high resolution spectrograph of the 2.16-m telescope in Xinglong Observatory,is introduced.The astro-comb is based on an ytterbium-doped fiber laser frequency comb.By mode filtering,the mode spacing of the comb is increased to25 GHz,which matches the resolution of the astronomical spectrograph.After spectral broadening and flattening,the spectrum span increases to more than 270 nm in visible range,the spectrum flatness maintains within 1dB for a long time,and the side mode suppression ratio reaches 42 dB.The theoretical calibration precision of the radial velocity for the astro-comb reaches cm/s level,which meets the requirements for searching the earth-like extrasolar planets and directly detecting the acceleration of the cosmic expansion.