4:00 PM - 4:30 PM
▲ [15p-C301-8] [JSAP-OSA Joint Symposia 2016 Invited Talk] Discrete Fourier transform spectroscopy using precisely periodic THz pulse train
Keywords:terahertz, Fourier transform spectroscopy
Fourier transform spectroscopy (FTS) has been widely used in a variety of fields due to its high signal-to-noise ratio, simultaneous acquisition of a broad spectrum, and versatility for different radiation sources. Further improvement of the spectroscopic performance will widen its scope of applications. Here, we demonstrate improved spectral resolution by overcoming the time window size limitation using a mode-locked terahertz (THz) pulse train as precisely periodic pulsed radiation in discrete Fourier transform spectroscopy (dFTS). Since infinitesimal resolution can be achieved at harmonic components of its repetition frequency 1/T when the time window size is exactly matched to the repetition period T, a combination of dFTS with a spectral interleaving technique achieves a spectral resolution only limited by the spectral interleaving interval. Linewidths narrower than 1/(50T) are fully resolved by THz-dFTS, allowing rotational-transition absorption lines of low-pressure molecular gases to be attributed within a 1.25-MHz band.