Ken-ichi Kondo

Dual-comb spectroscopy for rapid characterization of complex optical properties of solids

We demonstrate rapid characterization of complex optical properties of solids via dual-comb spectroscopy (DCS) in the near-infrared region. The fine spectral structures in the complex refractive index of an Er:YAG are successfully deduced using the developed system and Fourier analysis. Moreover, simultaneous determination of the refractive index and the thickness is demonstrated for a silicon semiconductor wafer through the use of multireflected echo signals. The results indicate the potential of DCS as a powerful measurement tool for the rapid and full characterization of solid materials.

Dual-comb spectroscopy for solid-state physics and extension toward time-resolved measurement

Dual-comb spectroscopy was applied for characterization of complex refractive-index of a Si wafer and transient interferogram by optical excitation in an InGaAs-based saturable absorber. Full-characterization tool with wide dynamic-range in time- and frequency-domain is provided.

Portable and stable dual-comb spectroscopic system based on an all-fiber setup

Dual-comb spectroscopy is a powerful spectroscopic method that can measure broadband spectral information with high accuracy and a short acquisition time. We have been particularly developing a new method to evaluate the complex refractive index of solid samples based on the dual-comb technique. In this research, we aimed to realize a simple and practical dual-comb spectroscopic system with broad applicability to samples and measurement conditions by developing an all-fiber-type dual-comb spectroscopic system, which is compact, stable, and easy to use.

Precise birefringence measurement of anisotropic materials by dual-comb spectroscopy

Dual-comb spectroscopy (DCS) is a new Fourier spectroscopic method which realizes precise and rapid spectral detection with a broad bandwidth. In this study, we applied DCS to characterization of birefringence of anisotropic materials. As a demonstration, we evaluated the refractive index and the birefringence of an anisotropic crystal, Nd:YVO4. We confirmed the evaluated values were consistent to some reference data, and our proposed scheme was successfully performed as the precise and rapid characterization method of the birefringence. It is expected that this technique will become a useful tool in a wide range of applications such as laser developments.

Time-Resolved Fourier Measurement for Semiconductors by Near-Infrared Dual-Comb Spectroscopy

Complex near-infrared refractive-index spectra of Si and GaAs wafers were characterized by dual-comb spectroscopy (DCS). Transient interferogram was observed for an InGaAs-based saturable absorber in time-resolved DCS, demonstrating potential as a full-characterization tool.