We have developed accurate optical frequency standards based on acetylene absorption lines in the telecom region (C-band) and have measured their optical frequencies using several kinds of optical frequency combs. Based on these results, in 2004 we started optical frequency (wavelength) calibration service for stabilized Cband lasers at National Metrology Institute of Japan (NMIJ). We also have the preliminary results of our experiments in transferring wavelength standards via optical fiber networks.
