Fiber-based time-domain spectroscopy: an emerging alternative to Raman and FTIR spectroscopy in space exploration or environmental studies? (Invited Paper)

Robotic missions to objects in our solar system are nowadays often equipped with instruments allowing to explore the geochemistry of the surfaces by e.g. identification of their characteristic vibrational fingerprints. Femtosecond fiber lasers have in recent years been shown to be in principle space qualified, opening up the opportunity to explore the potential of different time-domain techniques as compact, robust alternatives to e.g. Raman spectroscopy or FTIR spectroscopy. In this contribution the potential of two time-domain techniques: (i) coherent phonon spectroscopy (CPS) and (ii) THz Time-Domain Spectroscopy (THz-TDS), as emerging in-situ spectroscopic techniques to identify solids by their characteristic phonon spectra is discussed based on exemplarily measurements of different (planetary) materials. It is shown that: (i) CPS can give access to the raman-active phonon spectra equibvalent to Raman spectroscopy but is not hampered by fluorescence backgrounds and (ii) THz-TDS allows to probe the infrared-active fingerprint of matter while avoiding bulky (cryogenic) infrared detectors. The current status of the development of a compact all-fiber based instrument is discussed.