関西光科学研究所　|　第62回KPSIセミナー 時間伸張分光法によるビルドアップフェムト秒パルスのスペクトルダイナミクス

関西光科学研究所 >> KPSIセミナー >> 時間伸張分光法によるビルドアップフェムト秒パルスのスペクトルダイナミクス

セミナー

第62回KPSIセミナー

時間伸張分光法によるビルドアップフェムト秒パルスのスペクトルダイナミクス

時間伸張分光法によるビルドアップフェムト秒パルスのスペクトルダイナミクス

鈴木 将之 准教授
（同志社大学 理工学部 電気工学科）

概要

Mode-locked fiber lasers can produce a broadband spectrum and ultrashort pulse with compact size, environmentally stable operation and alignment-free. The mechanism of mode-locked femtosecond laser is theoretically well-established, an experimental observation of a spectral dynamics between cw and mode-locked operations, however, still remain because a conventional spectrometer cannot directly measure the single-shot spectrum in real time. Thanks to the single-shot spectrum measurement of a photonic time stretch spectroscopy [1], the single-shot spectrum is enabling to observe in real time. In our recent studies, we have successfully measured the 7220 consecutive single-shot spectra over a 100μs time window in real-time with time stretch dispersive Fourier transform (TS-DFT). As a novel result, we demonstrate the first observation of periodic spectrum changing via soliton explosion in a homemade passively mode-locked Yb fiber laser by a nonlinear polarization evolution [2]. By optimizing the intracavity condition in fiber laser, the periodic spectrum changing could be controlled between two stable mode-locked condition. In contrast, to directly observe the birth of femtosecond pulse in the cavity, we have measured the spectral dynamics from cw to mode-locked in a homemade Yb fiber laser with saturable absorber mirror by using TS-DFT. As an initial result, a dissipative soliton motion has experimentally observed before onsetting stable mode-locked state. In this seminar, we present on our recent result of spectral dynamics in mode-locked fiber lasers, and our research plan of an ultrafast spectroscopy with TS-DFT.

[1] A. Mahjoubfar, D. V. Churkin, S. Barland, N. Broderick, S. K. Turitsyn, B. Jalali, Nat. Photon. 11(6) 341-351 (2017).

[2] M. Suzuki, O. Boyraz, H. Asghari, P. Trinh, H. Kuroda, and B. Jalali, “Spectral periodicity in soliton explosions on a broadband mode-locked Yb fiber laser using time-stretch spectroscopy,” Opt. Lett. 43(8), 1862-1865 (2018).

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