Ultrahigh-Resolution Direct-Frequency-Comb Spectrometer

Direct frequency comb spectroscopy of HCN to evaluate line lists

“…The experimental set-up shares some similarities with several other previously reported comb-mode-resolved spectrometers. 24–29…”

“…The experimental set-up shares some similarities with several other previously reported comb-mode-resolved spectrometers. [24][25][26][27][28][29] The cylindrical lens creates a line-focused beam prole at the entrance of the VIPA etalon, as illustrated in the top of Fig. 2.…”

Three Phase Spectral Interferometry (3PSI) for recording high dynamic range optical waveforms with <1 ps resolution over >2 ns records applied to closed-loop pulse shaping

“…These spots ideally vary linearly across the detector array as a function of wavelength, though their variation often exhibits a slight sigmoidal shape as they approach the edges of the imaging field. The spectrum is typically 'unwrapped' from the raw image data by tracing out these paths as close as possible and summing the traces [17,18]. The result is a reconstruction of the underlying spectrum with exceptionally high spectral resolution, though this reconstruction technique does result in small distortions.…”

Optical Frequency Combs for Molecular Spectroscopy, Kinetics, and Sensing

“…A second orthogonal dispersive optical element separates overlapping VIPA mode orders to create a two-dimensional image. The resulting spectrum can be read out with comb-mode resolution 54,55 53,[55][56][57][58] While the interferometric and dispersive detection methods already mentioned have facilitated the bulk of comb spectroscopies relevant for chemistry, a plethora of other methods have been demonstrated and are worth brief mention here, including electro-optic sampling of THz and mid-IR comb pulses, 59,60 Vernier spectroscopy, 61,62 broadband photoacoustic spectroscopy, [63][64][65] cavity-enhanced ultrafast transient absorption, 66 Ramsey comb spectroscopy, 67 and comb-based quantum logic spectroscopy. 68,69 Some of these developments will be discussed in further detail later on in this Chapter.…”