Abstract
Optical frequency comb (OFC) is a revolutionary tool for frequency measurement. It links Cesium clock and optical frequency with a single mode-locked laser. This direct link enables the OFC to work as an absolute frequency measurement tool itself. We measured the absolute frequency of seventeen R-branch transitions of ν3 fundamental band of Nitrous Oxide (N2O) from J= 5 to J= 45 using an OFC. We investigated the saturation spectra of these transitions using a Periodically Poled Lithium Niobate (PPLN) Difference Frequency Generation (DFG) source. Refined molecular constants of N2O 0001 vibrational level are also obtained. In addition, we have improved the performance of our OFC by replacing the old Spectra Physics pump laser (Millennia V) with a Coherent Verdi G5 laser. The average power and stability greatly improved and the warm-up time was reduced from few hours to less than 30 minutes.