Multi-comb coherent control for material studies*

Dual-comb spectroscopy (DCS), which uses two frequency combs with slightly different repetition frequencies, has become a powerful tool for high-precision spectroscopy because of its capability for rapid, broadband, high-resolution, and high-sensitivity measurement. Recently, the applicability of the DCS has greatly expanded to such as nonlinear spectroscopy and solid-state study. By utilizing the DCS as the tool to retrieve the dynamical response of the electric field of the optical wave in the sub-PHz frequency domain, we can directly obtain the complex optical properties of the materials as the response function, which provides an attractive tool for direct characterization of new materials without model assumption. We have applied the technique for direct characterization of the complex optical properties of solid materials [1] and studying ultrafast phenomena [2].
In this study, we focused on the coherent controllability with multi-comb and realized generation and coherent detection of the raid polarization modulation of ultrashort pulse train. The technique was applied to the dynamical characterization of complex optical tensor of material. Moreover, we realized the spatio-temporal phase control of ultrashort pulse train by combining the optical frequency comb and optical vortex, i.e., optical vortex comb, and applied to the DCS for azimuth sensitive spectroscopy with all the advantages of the standard DCS. Such technique is useful for coherent excitation and control of orbital angular momentum related phenomena, such as topological physics, spintronics, and chiral material.
[1] A. Asahara, A. Nishiyama, S. Yoshida, K. Kondo, Y. Nakajima, and K. Minoshima, Opt. Lett., 41, 4971 (2016).
[2] A. Asahara and K. Minoshima, APL Photonics, 2, 041301 (2017).