利用單壁奈米碳管之被動鎖模掺釹釩酸釓雷射

Abstract

我們使用一種全新的方法製作不含聚合物的單壁奈米碳管薄膜，作為可承受高功率光照射的飽和吸收體。利用一系列不同濃度的單壁奈米碳管飽和吸收體，我們可以在1微米的光譜範圍內研製掺釹釩酸釓鎖模雷射。經由非線性穿透量測，得知單壁奈米碳管飽和吸收體擁有630飛秒的快速回復時間以及約百分之3的調變深度。在輸入功率為15瓦之下，此雷射操作波長為1063奈米，產生3.63瓦最大輸出功率、脈衝寬度約9.8皮秒和重複頻率121.8兆赫茲的連續波鎖模脈衝；其對應之脈衝能量30奈焦耳、最高脈衝峰值功率3千瓦以及61分貝之高消噪比。 據我們所知，這是使用單壁奈米碳管作為飽和吸收體的報導中，所產生最高的連續波鎖模輸出功率。

We used a new fabrication method of single-walled carbon nanotubes (SWNT) absorber without polymer to sustain high power illumination. Using a series of saturable absorbers (SAs) with different concentrations of SWNTs, mode locking is demonstrated for an Nd:GdVO4 laser in 1-μm spectral range. The measured nonlinear transmission of the SWNT-SAs shows a modulation depth of ~ 3% with fast recovery time of 630 fs. Continuous-wave mode-locking (CWML) pulses with maximum output power of 3.6 W, pulsewidth of about 9.8 ps and high noise extinction of 61 dB at 1063 nm has been achieved to give the highest pulse peak power of 3 kW and pulse energy of 30 nJ under 15 W pumping. To our knowledge, this is the highest CWML output power with SWNT-SAs reported.