全光學寡載波週期之超短脈衝互相關聲圖量測

Toward all-optical sub-cycle visible-to-infrared pulse envelope measurement via cross-correlation sonogram

呂軒豪(Lu, Hsuan Hao)

指導教授 ： 楊尚達

國立清華大學/電機資訊學院/光電工程研究所/碩士(2016年)

摘要

在這份論文中，我們提出一個新的量測技術：「互相關聲圖量測」，用來解析寬度短至單週期以下的超短脈衝的時域形狀。傳統的量測方法，例如「頻域分辨光學開關」和「頻譜干涉技術」大多受限於嚴重的群相速不匹配而須使用非常短的非線性晶體來進行量測。由於「互相關聲圖量測」將超寬的頻譜每次只擷取一部分出來和另一個已知的光學脈衝進行互相關強度量測，因此可以成功避開群相速不匹配的狀況，並得以使用較長的晶體來獲得更高的量測效率。
我們在模擬中成功利用100微米的硼酸鋇晶體解析一個從400奈米至980奈米的超連續光譜的相位，對應到時域上是寬度僅有2.3飛秒（0.88載波週期）的超短脈衝。在論文中我們也詳細討論了「互相關聲圖量測」中不同參數的選擇和其影響。我們認為這個方法相較於其他提出的脈衝量測技術有彈性，且量測的靈敏度更高。

關鍵字

超快雷射 ； 非線性光學 ； 脈衝量測

並列摘要

Single-to-sub-cycle pulses in the visible-to-infrared region have strong potential to produce isolated attosecond burst, which can be used in observing the fleeting electronic dynamics. Though streaking technique is able to characterize the driving pulse with attosecond resolution, complex apparatus and extremely high laser intensity is required. All-optical techniques, such as frequency-resolved optical gating (FROG) or spectral shearing interferometry, are much more simplified and sensitive. However, they are severely restrained by the enormous group velocity mismatch in measuring sub-5 fs pulses. Sonogram techniques can be all-optical, but catch less attention than their FROG siblings due to the complexity of the experimental setup.

In this work, we propose a cross-correlation scheme to fully access the great potential of sonogram in single-to-sub-cycle pulse measurement. By using a synchronized reference pulse of duration to measure the temporal intensity of each filtered signal spectrum via intensity cross-correlation (IXC), the required phase-matching bandwidth in IXC can be greatly relaxed. Our simulations show accurate spectral phase retrieval of a multi-plate continuum (MPC) spectrum with temporal duration down to 2.3 fs (0.88 cycle) by using a 100-um-thick BBO crystal (too thick for any existing all-optical methods).

並列關鍵字

Ultrafast Laser ； Ultrafast Measurement ； Ultrafast Nonlinear Optics

參考文獻

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