1.5μm wavelength region is the window of optical communication. Absolute frequency references that satisfy ITU-T standards in 1.5 μm region for frequency calibration are widely needed in DWDM system. In this paper, an approach of obtaining precise frequency points which ITU-T has produced has been experimented, using an acoustic frequency shift, by calibrating Fabry-Perot etalon using double acetylene absorption lines. In the experiment, mode 1955 of F-P etalon is offset frequency-locked to acetylene absorption line P14, 195500.4023GHz, with frequency stability 108 for a 30-minute measurement. After calibrating, a series of spaced 100GHz artificial absolute frequency references in 1.5μm region are obtained.
Absolute frequency reference in 1.5-μm wavelength region is very useful for DWDM system. We have studied on producing artificial 1.5-μm wavelength region absolute frequency reference by calibrating the F-P etalon. Double acetylene absorption line calibrating technique was adopted. An experiment of calibrating the Fabry-Perot etalon using double acetylene absorption lines has been demonstrated. In the experiment, Mode 1996 of the F-P etalon was locked to acetylene absorption line 1533.4621 nm. The frequency stability of the calibrated F-P etalon was about 7×10<sup>-8</sup>. After calibrating, a series of artificial absolute frequency references in 1.5-μm wavelength region was obtained. To reduce the complexity of calibrating, a novel frequency difference measurement method was introduced.