High-resolution spectroscopy combined with the use of optical frequency comb and heterodyne detection

We propose what we believe to be a new method of high-resolution spectroscopy based on a single-sideband (SSB) optical modulator combined with an optical frequency comb. A spectral resolution of less than 1 MHz on the absolute frequency axis was ensured using the SSB optical modulator and a frequency-locked laser diode. Also, the measurement frequency range was expanded by installing an optical frequency comb into the light source, in which the peak intensity was individually measured by the optical heterodyne detection method. The performance was experimentally confirmed using a 1 MHz width resonator and a (HCN)-C-13-N-14 gas cell. As a result, the measurement frequency range achieved was over 3 THz (1530-1560 nm) with a spectral resolution of less than 1 MHz. (C) 2010 Optical Society of America