Progress toward absolute frequency measurements of the 127 I2-stabilized Nd:YAG laser at 563.2 THz/532 nm

Progress on the development of a frequency chain devoted to the absolute frequency measurement of ¹²⁷I₂-stabilized lasers around 563.2 THz/532 nm is reported. The aim of this work is the improvement of the accuracy-by at least one order of magnitude-of the absolute frequency of this standard. The scheme is based on the frequency combination of two well-known optical frequency standards, namely a CO₂ laser stabilized on OsO₄, and a 778-nm diode laser stabilized on Rb measured, at BNM-LPTF, against a cesium primary standard with 2×10^-13 and 2×10^-12 relative uncertainty respectively. This last value gives the ultimate accuracy of the reported chain