以高效率單通光參數產生近1.4微米超快脈衝雷射光源

Abstract

可調超短脈衝雷射光源對於光譜學及光學顯微術相當重要。我們以摻氧化鎂之周期極化反轉鈮酸鋰(MgO:PPCLN)架設出一單通光參數產生光源，產生波長接近1.3~1.4微米的可調波長光源。其架設極其簡單:僅僅將超短脈衝摻鐿光纖雷射聚焦到MgO:PPCLN；而可以約65%的高效率，將波長1.0微米的95 nJ脈衝序列轉換到近1.4微米。在數十MHz高重覆率的情況下，比我們目前所知效率最高者多近20%。 這個光參數轉換光源具備高重覆率、高轉換效率以及簡單的架構，是理想的生醫影像或非線性影像光源。

Tunable ultrafast light sources are important for various spectroscopic and microscopic applications. In this work we have developed a wavelength-tunable source near 1.3-1.4 μm spectral range based on a single-pass optical parametric generation (OPG) in a multi-period magnesium oxide doped periodically poled lithium niobate (MgO:PPCLN) crystal. This OPG setup, simply by focusing ultrashort pulse ytterbium-doped fiber laser pump on highly efficient nonlinear crystal MgO:PPCLN without any seeding or oscillators, display near 65% of max conversion efficiency near 1.4 μm out of 95 nJ pump pulse; which is the highest efficiency at such high repetition rate and not expected in ordinary OPG. Combined with 43 MHz repetition rate and wavelength near optical window, this source is ideal for biomedical imaging and spectroscopic applications.