イベント情報
【GIR公開セミナー】Dr. Li Hua / Shanghai Institute of Microsystem and Information Technology, CAS（中国）
| 日時 | 2024.10.16（15：00～16：00） |
|---|---|
| 会場 | |
| Google Classroom コード | 25wce2h |
| 講演者 | Dr. Li Hua |
| 所属機関 | Shanghai Institute of Microsystem and Information Technology, CAS （中国） |
| 講演タイトル | "Broadband terahertz frequency comb and dual-comb operation under microwave injection" ＜要旨＞ Broadband frequency comb and dual-comb sources are of great importance for high precision applications, e.g., spectroscopy, imaging, communications, etc. Specifically, the dual-comb technique can allow retrieving Fourier spectra without the need of moving interferometric components, thereby offering new possibilities for real-time and high-resolution spectroscopic measurements. In the terahertz (THz) frequency range, broadband quantum cascade lasers (QCLs) are the most powerful chip-scale sources for frequency comb and dual-comb operation. However, the limited gain bandwidth and chromatic dispersion of THz QCLs have constrained the comb-based applications. In this presentation, I will review the broadband THz QCL frequency comb and dual-comb sources by employing microwave injection techniques. For frequency comb operation, it is shown that the resonant microwave injection is a powerful tool to stabilize the repetition frequency and broaden the emission spectrum of the THz QCL combs. Regarding the dual-comb operation, we experimentally implement the microwave injection onto two THz QCL combs and broadband dual-comb operation is achieved. In the dual-comb experiment, a THz QCL structure with a stacked active region which shows a calculated gain bandwidth spanning from 3.35 to 3.83 THz is used. The measured lasing bandwidth in free-running is broadened from 250 GHz (single active region) to 470 GHz (stacked active region) which agrees well with the simulation. Although broad THz emission can be obtained at relatively high drive currents, the laser normally demonstrates chaotic emission behavior due to the high phase noise introduced by the strong electrical pumping. Herein, by employing a microwave injection technique, we observe a clear transition from chaos to broadband dual-comb operation in the THz QCL with the stacked active region. The measured optical bandwidth is ∼400 GHz, which reaches 73% of the lasing bandwidth of the THz QCL (550 GHz under microwave injection). The mechanism of the phase noise compression induced by the external microwave injection can be associated with the modulation of group velocity dispersion and phase matching in the THz QCL, which further enhances the four-wave mixing locking effect for the broadband dual-comb operation. |
| 言語 | 英語 |
| 対象 | どなたでも、ご参加いただけます。 |
| 共催 | グローバルイノベーション研究院 ライフサイエンス分野 梅林チーム 卓越大学院プログラム |
| お問い合わせ窓口 | グローバルイノベーション研究院・工学研究院 張 亜 e-mail: zhangya（ここに@ を入れてください）go.tuat.ac.jp |
| 備考 | 本セミナーは、対面型のみの開催となります。 |
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