Characterization of octave-spanning continuum generated from multiple SiO2 plates

鄒侑融(Yu-Jung Tsou)

指導教授 ： 孔慶昌

國立清華大學/電機資訊學院/光電工程研究所/碩士(2014年)

摘要

超八度的超連續頻譜是產生獨立亞飛秒超短脈衝的關鍵。近期實驗室發展出一個產生俱有超八度連續頻譜的超短脈衝技術：使用多重熔融石英片進行展頻 (MPContinuum)。超八度連續頻譜可壓縮成為一個時域上為亞飛秒等級的超短脈衝，但頻域上俱有如此高頻寬的超短脈衝，其時間上的長度非常容易受到色散影響。因此超八度連續頻譜的超短脈衝相位量測非常重要。在此論文中我們使用偏振閘互相關頻率解析光閘 (polarization-gating cross-correlation frequency-resolved optical gating ，縮寫為PG-XFROG) 進行超八度連續頻譜的超短脈衝相位量測。由量測到的偏振閘互相關頻率解析光閘頻譜圖 (PG-XFROG trace) ，藉由相位重建疊代演算法可重建出此超八度連續頻譜的脈衝相位。透過疊代演算得出的脈衝資訊，可讓我們更了解此展頻過程中的物理機制，並將量測出的相位進行壓縮，產生獨立亞飛秒超短脈衝。

關鍵字

超快雷射 ； 頻率解析光閘 ； 脈衝量測 ； 超連續頻譜 ； 多重熔融石英片展頻 ； 超八度連續頻譜

並列摘要

An octave-spanning supercontinuum is the key to achieve isolated sub-femtosecond pulses. Recently our laboratory developed a new technique to generate ultrashort pulses that have an octave-spanning continuous spectrum using a set of multiple fused silica plates (MPContinuum). For such a broadband spectrum, the pulse width is sensitive to dispersion. Thus, characterization of the pulse with an octave-spanning supercontinuum is important. Here, we demonstrate using polarization-gating cross-correlation frequency-resolved optical gating (PG-XFROG) to characterize an octave-spanning visible spectrum. A PG-XFROG trace with octave-spanning spectrum is measured. From this trace and using our iterative phase-retrieval algorithm, we can retrieve the spectral phase and amplitude of the MPContinuum generated in our laboratory. The full characterization of the MPContinuum pulses helps us in theoretically analyzing the generation process, and allows precise compression of the octave-spanning supercontinuum pulses to the sub-femtosecond regime.

參考文獻

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