Accurate frequency standard at 1556.2 nm based on a two-photon transition in rubidium for absolute calibration of WDM systems

摘要

With the increasing number of optical carriers and the narrowing of the channel spacing, dense WDM systems require absolute frequency control of their settings [1]. Optical frequency standards are being developed for the purpose of generating referencing scales, controlling the frequency of the WDM transmitters and calibrating measurement equipment and WDM frequency sensitive devices. Relatively simple frequency standards are based on the use of frequency-locked lasers to acetylene or hydrogen cyanide lines [2, 3]. Recently, a two-photon transition of rubidium at 778 nm [4] was used to lock a frequency-doubled 1556 nm laser that was used as a reference to improve the precision of the calibration of acetylene transitions [5]. We have developed a compact and portable version of this new at 1556.2 nm [6] and proceeded to an absolute frequency measurement by comparison with a Cs-primary frequency standard [7]. We present in this paper the results obtained in the frequency characterization of this new standard which reveals to be the most precise at the present time.