Photon-counting optical time domain reflectometry(v-OTDR)is typically used in a mode with spatial resolution in the centimeter range.Here we demonstrate a 1550 nm v-OTDR system to optimize the discriminate voltage of ...Photon-counting optical time domain reflectometry(v-OTDR)is typically used in a mode with spatial resolution in the centimeter range.Here we demonstrate a 1550 nm v-OTDR system to optimize the discriminate voltage of a single photon avalanche detector using a single photon modulation and demodulation technique,which shows obvious improvement in the signal intensity.The intensity of signal is doubled when the discriminator voltage is optimized from 184 mV to 162 mV.展开更多
High resolution two-photon spectrum of the transitions 6S_(1/2)→6P_(3/2)→8S_(1/2),9S_(1/2) and 6S_(1/2)→6P_(1/2)→7D_(3/2) in neutral ^(133)Cs are presented in a room-temperature vapor cell using a femtosecond opti...High resolution two-photon spectrum of the transitions 6S_(1/2)→6P_(3/2)→8S_(1/2),9S_(1/2) and 6S_(1/2)→6P_(1/2)→7D_(3/2) in neutral ^(133)Cs are presented in a room-temperature vapor cell using a femtosecond optical frequency comb.Spectra are obtained by scanning the repetition frequency of the femtosecond optical frequency comb over the two-photon hyperfine structure.The centroid frequency of the 6S_(1/2)→8S_(1/2),9S_(1/2),7D_(3/2) transitions are 729009798.80(17)MHz,806761363.96(11)MHz,and 780894762.595(23)MHz,respectively.The hyperfine coupling constants of the corresponding states are also obtained.The results are consistent with the previous measurements.展开更多
We have produced ultracold polar RbCs molecules via photoassociation starting from laser-cooled 85Rb and 133Cs atoms in a dual−species,forced dark magneto-optical trap.The formed electronically excited RbCs∗molecules ...We have produced ultracold polar RbCs molecules via photoassociation starting from laser-cooled 85Rb and 133Cs atoms in a dual−species,forced dark magneto-optical trap.The formed electronically excited RbCs∗molecules correlated to the Rb(5S_(1/2))+Cs(6P_(1/2))dissociation limit are observed by trap loss spectroscopy.Following the decay of these excited RbCs*molecules,the formed ground state molecules are directly ionized by a two-photon single-color pulse dye laser,which is a new ionization mechanism for ground state RbCs molecules and thence detected by time-of-flight mass spectroscopy.展开更多
基金by the National High-Tech Research and Development Program of China under Grant No 2009AA01Z319the National Basic Research Program of China under Grant Nos 2006CB921603,2006CB921102 and 2010CB923103+3 种基金the National Natural Science Foundation of China under Grant Nos 10674086 and 10934004the National Natural Science Foundation of China for Excellent Research Team under Grant No 60821004TSTIT and TYMIT of Shanxi ProvinceShanxi Province Foundation for Returned Scholars。
文摘Photon-counting optical time domain reflectometry(v-OTDR)is typically used in a mode with spatial resolution in the centimeter range.Here we demonstrate a 1550 nm v-OTDR system to optimize the discriminate voltage of a single photon avalanche detector using a single photon modulation and demodulation technique,which shows obvious improvement in the signal intensity.The intensity of signal is doubled when the discriminator voltage is optimized from 184 mV to 162 mV.
基金Supported by the National Basic Research Program of China under Grant No 2012CB921603the National High-Technology Research and Development Program of China under Grant No 2011AA010801+4 种基金the National Natural Science Foundation of China under Grant Nos 61008012,61378049,10934004 and 11174187International Science&Technology Cooperation Program of China under Grant No 2011DFA12490the NSFC Project for Excellent Research Team under Grant No 61121064the Natural Science Foundation of Shanxi Province under Grant Nos 2011011004 and 2011081030the New Teacher Fund of the Ministry of Education of China under Grant No 20101401120004.
文摘High resolution two-photon spectrum of the transitions 6S_(1/2)→6P_(3/2)→8S_(1/2),9S_(1/2) and 6S_(1/2)→6P_(1/2)→7D_(3/2) in neutral ^(133)Cs are presented in a room-temperature vapor cell using a femtosecond optical frequency comb.Spectra are obtained by scanning the repetition frequency of the femtosecond optical frequency comb over the two-photon hyperfine structure.The centroid frequency of the 6S_(1/2)→8S_(1/2),9S_(1/2),7D_(3/2) transitions are 729009798.80(17)MHz,806761363.96(11)MHz,and 780894762.595(23)MHz,respectively.The hyperfine coupling constants of the corresponding states are also obtained.The results are consistent with the previous measurements.
基金by the National Key Fundamental Basic Research Program of China(2006CB921603)Major Program of the National Natural Science Foundation of China(10934004)+2 种基金the National Natural Science Foundation of China(60978018,60808009,61008012,and 60978001)the New Teacher Fund of Ministry of Education of China(200801081021)NSFC Project for Excellent Research Team(Grant No 60821004).
文摘We have produced ultracold polar RbCs molecules via photoassociation starting from laser-cooled 85Rb and 133Cs atoms in a dual−species,forced dark magneto-optical trap.The formed electronically excited RbCs∗molecules correlated to the Rb(5S_(1/2))+Cs(6P_(1/2))dissociation limit are observed by trap loss spectroscopy.Following the decay of these excited RbCs*molecules,the formed ground state molecules are directly ionized by a two-photon single-color pulse dye laser,which is a new ionization mechanism for ground state RbCs molecules and thence detected by time-of-flight mass spectroscopy.
