利用測半導體光偵測器中的單光子和雙光子干涉相關器來還原超快波形與相位

Abstract

為了量測超短脈衝,我們成功的組裝了一套簡便、便宜的光子吸收自相關器;首先,我們採用一種演算法(IRIS),可以用來還原其脈衝波形,同時我們以電腦模擬出兩種不同形式的脈衝,順向的模擬出其單雙光子的吸收訊號圖,接著利用此種演算法,重建還原出原來的脈衝波形,結果發現還原曲線和模擬曲線相當吻合,其誤差約10-3。我們量測出了脈衝雷射的單雙光子自相關吸收訊號,並利用此種方法還原出原來的脈衝波形,發現在兩種不同的情形下,雷射脈衝的波形與相位會有相當大的不同,藉由分析兩者的差異,我們可了解在雷射腔內脈衝變化與啾頻現象。最後,探討如何優化實驗裝置,並可將此方法應用於量測材料非線性參數上。

To measure the ultrafast pulse, we set up a simple and inexpensive interferometric autocorrelator. We use an algorithm (Iterative Pulseform Reconstruction from Interferometric Signals, developed by K. Naganuma et al.) to retrieve the pulse waveform and phase from the autocorrelator data. In order to make sure the phase retrieval algorithm and computer program are adequate, we first simulate the correlation signals, then convert them back to the original pulse and phase within 10-3error. By measuring the interferometric correlation signals, we find the difference of two adjustment of our Kerr lens mode-locked Ti: sapphire laser. We not only obtain pulse shape and chirping in the laser but also its spectrum which agrees with the experimental result. The technique can be applied to improve performance of ultrafast laser as well as to study the nonlinear optical properties of materials.