MENU
Activities
Research Subjects
We developed an injection-seeded THz-wave parametric generator (is-TPG) with wide frequency tuning, small size, room-temperature operation. It emits the monochromatic THz-wave over a wide tunable frequency range from 0.4 THz to 2.8 THz with the linewidth of lower than 100 MHz. Recently, a compact, table-top, high resolution THz-wave spectrometer based on the is-TPG is finished. Accurate and fast measurement of the absorption spectrum was realized. The pressure-varying absorption spectroscopy was observed. This result demonstrate the present is-TPG a new and powerful source for gas sensing, THz-wave spectroscopy in Far-IR regime.
Figure: THz-wave spectrometer based on an is-TPG.
A random-frequency-accessible terahertz (THz)-wave parametric oscillator (TPO) with a ring-cavity configuration was developed using a novel tuning method that involves rotating a single mirror forming a cavity. A widely tunable range from 0.9 to about 3.0 THz with a maximum output pulse energy of 100 pJ/pulse (peak: ~10 mW) was obtained. In THz-wave spectroscopy and THz-wave imaging using the TPO, the spectra of biomolecules were measured within a few seconds and an image of human liver cancer was acquired within a few minutes.
Figure: Photograph of the frequency-agile ring-cavity TPO

We propose a surface-emitted cavity configuration for a terahertz-wave parametric oscillator that allows THz wave emission perpendicular to the crystal surface without any output coupler. The oscillating idler and pump waves are reflected at the surface of a nonlinear crystal in a single resonance cavity, satisfying the noncollinear phase-matching condition. The radiated THz wave has a Gaussian profile. The measured beam quality factors (M2) were 1.15 and 1.25 in the horizontal and vertical directions, respectively. The measured tunable range was 0.8–2.74 THz.

Figure: THz-wave beam characteristics
We carried out the THz-wave application such as THz-wave spectroscopy and THz-wave spectroscopic imaging using a THz-wave parametric oscillator (TPO) or FT-IR spectrometer. We successfully observed the absorption peaks of many kinds of organic and inorganic molecules including bio samples.
We demonstrated THz-wave spectroscopic imaging of human tissue samples, including normal and cancerous, are reported using a THz-wave parametric oscillator output. We observed their spectral differences and produced a high-quality transmitted image.
Figure: (a) Temperature dependence spectra of tetracene. (b) THz transmission image of the human liver tissue at 1.8 THz
Collaboration Projects
This research is performed in a joint lab between Canon inc. and Riken
This research aims to develop a novel sensing technique with terahertz-wave.
The main activities in this research are to develop the micro device and the system for diagnosing or analysis of the function.
Exihibits
Annual reports
Awards