従来のモード同期レーザー開発では、スペクトルを広げることとパルス幅を縮めることが追求されてきました。しかし、気相分子のように励起状態のコヒーレンスが長く保たれる物質を高効率に共鳴励起するには、光エネルギーを狭い波長帯に集中させ、その中心波長を掃引できるレーザーが求められます。
そこで私たちは、中赤外域の広い範囲にわたって波長を掃引できる「狭線幅モード同期レーザー」を開発しました。本技術は、高分解能な分光計測や高感度な分子センシング、さらには量子状態制御の分野に大きく貢献すると期待されます。
Until now, the development of mode-locked lasers has largely focused on broader spectra and shorter pulses. However, to efficiently trigger resonant interactions in systems where excited-state coherence lasts a long time—like gas-phase molecules—we need a different kind of laser. It must concentrate its light energy into a consistently narrow bandwidth while rapidly tuning its center wavelength.
To achieve this, we have developed a new “narrow-linewidth mode-locked laser” that can rapidly tune its wavelength in the mid-infrared region. We expect this technology to greatly advance fields such as high-resolution spectroscopy, ultrasensitive molecular sensing, and quantum state control.
Fig. 1 Wavelength tuning performance of the developed narrow-linewidth mode-locked laser
- Z. Zhang, X. Bu, D. Okazaki, W. Song, I. Morichika, and S. Ashihara, “Tunable mode-locked laser in the 2.0–2.6 µm range with GHz-level spectral width and sub-nanosecond pulse duration,” Applied Physics Letters Vol. 126, 051104 (2025).
- Z. Zhang, W. Song, I. Morichika, and S. Ashihara, “Mode-Locked Cr:ZnS Laser with High-Speed Wavelength Sweeping,” The International Conference on Ultrafast Phenomena 2026 (UP 2026), Th-PO.56 (Sapporo, 2026.08.06).