An optical frequency scale in exact multiples of 100 GHz for standardization of multifrequency communications

Absolute laser frequency assignment in projected dense wavelength division multiplexing (DWDM) networks has become a very important issue for standardization purposes. Recently, a proposal was made to the International Telecommunication Union suggesting a set of standard wavelengths in the 1550 mn communications band. It recommended the use of a krypton line at 193.68625 THz as an absolute frequency reference and a set of 32 wavelengths evenly spaced by 100 GHz around that value. In this paper, we propose the use of an optical frequency scale with markers at exact multiples of 100 GHz for standardization. Our proposed scale is independent of the atomic or molecular species used for calibration (and thus accessible to any user), and moreover is uniformly applicable to all spectral regions. We show one way of implementing such a scale in the 1550 nm band through the use of an absolutely calibrated Fabry-Perot resonator set with a free spectral range of 100 GHz.