Madeikis Karolis, Kananavicius Robertas, Danilevicius Rokas, Zaukevicius Audrius, Januskevicius Regimantas, Michailovas Andrejus
Opt Express. 2021 Aug 2;29(16):25344-25357. doi: 10.1364/OE.433617.
In this work, we present the development of a femtosecond tunable middle infrared (mid-IR) radiation source for the realization of a hybrid concept compact broadband high-resolution sum-frequency generation (SFG) spectroscopy system. For the realization of the new concept, we used a two-channel picosecond fiber laser as a seed for narrowband (∼1.5 cm) and broadband ultrafast radiation sources operating at 1 kHz repetition rate. In order to achieve >500 cm bandwidth widely tunable microjoule level pulses in the mid-IR spectral region (2-10 µm), broadband femtosecond source optimization was performed. Numerical simulations with different nonlinear crystals and optical parametric amplification layouts at given fixed initial conditions paved a way to experimentally realize an optimal scheme for a femtosecond mid-IR channel. Fully operating SFG spectrometer setup was assembled and tested. The developed SFG spectrometer demonstrates a unique combination of parameters: excellent spectral resolution (<3 cm) similar to a narrowband scanning picosecond spectrometers and fast simultaneous acquisition of broadband spectra up to more than 850 cm.
在这项工作中，我们展示了一种飞秒可调谐中红外（mid-IR）辐射源的研制，用于实现一种混合概念的紧凑型宽带高分辨率和频产生（SFG）光谱系统。为实现这一新概念，我们使用了一个双通道皮秒光纤激光器作为种子源，用于重复频率为1 kHz的窄带（~1.5 cm）和宽带超快辐射源。为了在中红外光谱区域（2 - 10 µm）实现带宽大于500 cm的广泛可调谐微焦耳级脉冲，我们对宽带飞秒源进行了优化。在给定固定初始条件下，对不同非线性晶体和光学参量放大布局进行数值模拟为实验实现飞秒中红外通道的最优方案铺平了道路。组装并测试了完全运行的SFG光谱仪装置。所研制的SFG光谱仪展示了独特的参数组合：与窄带扫描皮秒光谱仪类似的出色光谱分辨率（<3 cm）以及高达850 cm以上宽带光谱的快速同时采集。
