氧化銀之三階非線性光學材料於全光學式光開關之應用

Abstract

超快全光學式光開關是下一代高容量通訊系統中的關鍵技術。為了要實現全光學式光開關元件，較大的三階非線性率、超快速的響應時間以及在室溫下可運作的非線性光學材料是不可或缺的。在這些材料中，金屬奈米粒子由於具有較大的三階非線性率以及快速的響應時間，因此在光開關及光學計算領域中已成為目前備受矚目的非線性光學材料。其中，銀和金奈米粒子由於在可見光的範圍內有因電漿子共振所造成的強烈吸收而更受到青睞。本論文的主要目標是以氧化銀材料為基礎，製造出在可見光範圍內有較大三階非線性率以及快速響應時間的氧化銀奈米粒子。 在本論文研究中，我們利用濺鍍方式以及加熱的步驟在玻璃基板上製造出氧化銀的奈米粒子。所得之平均粒子大小在48到87 nm之間，而其相對應之粒子電漿共振波長由420增加到450 nm。我們利用Z-scan量測估算出其三階非線性極化率的大小為6.68□10-10 (esu)，而在pump-probe實驗中，我們量測到氧化銀奈米粒子的反應時間大約為27 ps。

Ultrafast all-optical switching (AOS) is a key technology for the next generation high capacity communication systems. To implement AOS devices, nonlinear optical materials with strong third-order nonlinearity, ultrafast response time and operability at room temperature are required. Metal nanoparticles are of interest as nonlinear materials for optical switching and computing because of their relatively large third-order nonlinearities and fast response time. Silver and gold nanoparticles are of special interest as they exhibit particularly strong optical extinction in the visible spectral range due to resonant electron plasma oscillation. The main goal of this thesis is to fabricate the AgOx-based nanoparticles with large third-order nonlinearities and ultrafast response time in the visible spectral range. In this thesis, we have fabricated the AgOx nanoparticles on glass substrate by sputtering and annealing processes. The average particle size thus fabricated varies from 48 to 87 nm, and the particle plasmon resonance wavelengths increase from 420 to 450 nm with increase of particle size. We also estimated the value of the third-order nonlinear susceptibility ( ) as about 6.68□10-10 (esu) by Z-scan measurement. In the pump-probe measurement, we obtained the response time of AgOx nanoparticles is about 27 ps.