Highly precise laser frequency metrology at 1.5 μm using molecular lines

Our recent detection of sub-Doppler molecular saturated-absorption lines at 1.5 micrometers , using low power laser diodes, has opened the way to a precise frequency metrology at this wavelength. Our present goal is to establish a network of highly accurate reference frequencies in this wavelength band, and to provide the simplest way to generate them for a practical frequency metrology, which is of great interest for optical fiber communications, of high resolution spectroscopy. We present an overview of our efforts toward this goal, and we show that we can expect, in the near future, to be able to assign an absolute frequency value with a approximately 100 kHz precision for almost all the above-mentioned 1.5 micrometers frequency standards.