超宽调谐(2.6~5μm)中红外皮秒脉冲激光的研究

Study of Ultra-wide Tuning(2.6~5μm)Mid-infrared Picosecond Pulsed Laser

在超快脉冲激光中,超宽调谐通常应用于超连续谱产生、光谱分析和调制等多个领域。文章利用皮秒脉冲同步泵浦技术,搭建了一种基于MgO:PPLN晶体的“Z”形光参量振荡器,通过具有扇形周期极化的晶体在中红外波段产生了高功率、波长超宽调谐(2.6~5μm)的皮秒脉冲激光源输出。该振荡器由五镜一晶体组成,这五镜片的选择和精确调整是提高光参量振荡器输出性能的关键因素,采用波长为1.064μm的Nd:YVO_(4)皮秒脉冲激光源,选择周期在26~32μm可调谐的MgO:PPLN晶体,最大泵浦功率为15W时,2.66μm、3.44μm和4.99μm处获得了最大输出功率分别为3.41W、2.78W和0.52W的闲频光,相应的光-光转换效率分别为58%、55%、15%,测量到中红外光谱谱宽为2.37nm(2615nm)、Δλ=1.87nm(3687nm)、Δλ=1.30nm(4992nm),观察到在没有任何窄化光学元件条件下长脉冲随波长光谱谱宽具有线性变窄的过程。在2.6~4.5μm波段的激光输出功率均大于1W,实现了高功率,波长超宽调谐的中红外皮秒激光的连续输出。窄谱宽超宽调谐中红外皮秒脉冲激光为超快过程研究和应用领域提供了一种强大的工具。通过优化波长调谐范围和脉冲宽度能够满足不同领域对中红外激光的高要求,对推动相关领域的研究和发展至关重要。

In ultrafast pulsed lasers,ultrawide tuning is usually applied in various fields such as supercontinu⁃um generation,spectral analysis and modulation.In this paper,a"Z"type optical parametric oscillator based on MgO:PPLN crystals is constructed using picosecond pulsed synchronous pumping technology,and a high power,wavelength ultra-wide tuned(2.6~5μm)picosecond pulsed laser source is generated at mid-infrared wavelengths by the crystals with sector-periodic polarization.The oscillator consists of five mirrors and one crystal,and the selection and precise tuning of these five mirrors are the key factors to improve the output performance of the optical parametric oscillator.An Nd:YVO_(4)picosecond pulsed laser source with a wavelength of 1.064μm is used,and a MgO:PPLN crystal with a tunable period in the range of 26~32μm is selected.When the maximum pump power is 15W,the maximum output powers of 3.41W,2.78 W and 0.52W are obtained at wavelengths of 2.66μm,3.44μm and 4.99μm,respectively,and the corresponding photon conversion efficiencies are 58%,55%and 15%,respectively.The mid-infrared spectral spectral widths of 2.37nm(2615nm),Δλ=1.87nm(3687nm),andΔλ=1.30nm(4992nm)were measured,and a linear narrowing of the long pulse with wavelength spectral spectral widths was observed in the absence of any narrowing optics.The laser output powers in the 2.6~4.5μm band are all greater than 1W,realizing the continuous output of a high-power,wavelength-ultra-wide,broadly tuned mid-infrared picosecond laser.The narrow spectral width ultra-wide tuned mid-infrared picosecond pulsed laser provides a powerful tool for ultrafast process research and application areas.The optimization of the wavelength tuning range and pulse width can meet the high demands of mid-infrared lasers in different fields,which is essential to advance the research and development in related fields.