Optical fiber sensors must compete in performance with traditional electronic sensors, such as quartz crystal pressure and temperature monitors. The precision of commercial electronic sensors can reach the parts-per-billion (ppb) level. To test the precision of a laser based spectrometer system, repeated measurements of an absorption line of a molecular gas cell were made. The Allan deviation is computed, and it is shown that the laser interrogation system, built completely out of commercially available components, can achieve precision at the 10-ppb level.
We describe in detail an optical clockwork based on a 1 GHz repetition rate femtosecond laser and silica microstructure optical fiber. This system has recently been used for the absolute frequency measurements of the Ca and Hg+ optical standards at the National Institute of Standards and Technology (NIST). The simplicity of the system makes it an ideal clockwork for dividing down high optical frequencies to the radio frequency domain where they can readily be counted and compared to the existing cesium frequency standard.
In a ceramic vapor cell we have created a robust Sr magneto- optical trap that stores about 108 atoms with lifetimes > 200 ms. We eliminate the 5p 1P1 yields 4d1D2 yields 5p 3P2 leak and achieve a 10-fold improvement in trap lifetime by re-pumping the 5p 3P0,2 dark states with 679 nm and 707 nm light. The observed lifetime is now limited by cold collision losses, and we have preliminary measurements of the 2-body loss rate. Direct readout of the trap velocity distribution is possible using the narrow 5s21S0 yields 5p 3P1 intercombination line at 689 nm. We can also cool with this narrow transition and have achieved a 40-fold 1D velocity compression for about 5 percent of the trapped atoms by applying this second-stage cooling.