A laser frequency comb with several tens GHz level is demonstrated,based on a Yb-doped femtosecond fiber laser and two low-finesse Fabry-Perot cavities（FPCs） in series.The original 250-MHz mode-line-spacing of the s...A laser frequency comb with several tens GHz level is demonstrated,based on a Yb-doped femtosecond fiber laser and two low-finesse Fabry-Perot cavities（FPCs） in series.The original 250-MHz mode-line-spacing of the source comb is filtered to 4.75 GHz and 23.75 GHz,respectively.According to the multi-beam interferences theory of FPC,the side-mode suppression rate of FPC schemes is in good agreement with our own theoretical results from 27 dB of a single FPC to43 dB of paired FPCs.To maintain long-term stable operation and determine the absolute frequency mode number in the23.75-GHz comb,the Pound-Drever-Hall（PDH） locking technology is utilized.Such stable tens GHz frequency combs have important applications in calibrating astronomical spectrographs with high resolution.展开更多
We have presented a high resolution spectroscopy of Rb in magnetic field by far-detuning electromagnetically induced transparency(EIT).The EIT spectrum in theΞ-type configuration is usually companied by a double reso...We have presented a high resolution spectroscopy of Rb in magnetic field by far-detuning electromagnetically induced transparency(EIT).The EIT spectrum in theΞ-type configuration is usually companied by a double resonance optical pumping(DROP)due to the strong optical coupling between the two upper states,leading to the spectral lines seriously deformed and widely broadened for complex relaxation processes in DROP.Here we demonstrate a high resolution spectroscopy by far-detuning EIT for^(87)Rb 5S_(1/2)→5P_(3/2)→5D_(5/2)in magnetic fields.The method of far-detuning eliminates the relaxation in DROP to the most extent and decreases the spectral linewidth from more than 20 MHz down to its natural linewidth limit(6 MHz).The deformation of the spectral lines also disappears and the observed spectra are well in accordance with the theoretical calculation.Our work shows that far-detuning EIT is a reliable high resolution spectroscopic method when the relaxation in DROP cannot be neglected,especially for the case of transition to low excited states.展开更多
基金supported by the National Basic Research Program of China(Grant No.2012CB821304)the National Natural Science Foundation of China(Grant Nos.11078022 and 61378040)
文摘A laser frequency comb with several tens GHz level is demonstrated,based on a Yb-doped femtosecond fiber laser and two low-finesse Fabry-Perot cavities（FPCs） in series.The original 250-MHz mode-line-spacing of the source comb is filtered to 4.75 GHz and 23.75 GHz,respectively.According to the multi-beam interferences theory of FPC,the side-mode suppression rate of FPC schemes is in good agreement with our own theoretical results from 27 dB of a single FPC to43 dB of paired FPCs.To maintain long-term stable operation and determine the absolute frequency mode number in the23.75-GHz comb,the Pound-Drever-Hall（PDH） locking technology is utilized.Such stable tens GHz frequency combs have important applications in calibrating astronomical spectrographs with high resolution.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074388 and 12004393)
文摘We have presented a high resolution spectroscopy of Rb in magnetic field by far-detuning electromagnetically induced transparency(EIT).The EIT spectrum in theΞ-type configuration is usually companied by a double resonance optical pumping(DROP)due to the strong optical coupling between the two upper states,leading to the spectral lines seriously deformed and widely broadened for complex relaxation processes in DROP.Here we demonstrate a high resolution spectroscopy by far-detuning EIT for^(87)Rb 5S_(1/2)→5P_(3/2)→5D_(5/2)in magnetic fields.The method of far-detuning eliminates the relaxation in DROP to the most extent and decreases the spectral linewidth from more than 20 MHz down to its natural linewidth limit(6 MHz).The deformation of the spectral lines also disappears and the observed spectra are well in accordance with the theoretical calculation.Our work shows that far-detuning EIT is a reliable high resolution spectroscopic method when the relaxation in DROP cannot be neglected,especially for the case of transition to low excited states.
