Mid-Infrared Frequency Comb Generation and Spectroscopy with Few-Cycle Pulses and χ(2) Nonlinear Optics
Mid-Infrared Frequency Comb Generation and Spectroscopy with Few-Cycle Pulses and χ(2) Nonlinear Optics
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DOI：
10.1103/physrevlett.124.133904
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发表时间：
2020-04-01
影响因子：
8.6
通讯作者：
Diddams, Scott A.
中科院分区：
文献类型：
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作者：
Lind, Alexander J.;Kowligy, Abijith;Diddams, Scott A.
3-5.5 μ m的中红外大气窗口为基础和应用光谱学提供了有关分子组成和功能的宝贵信息。利用近红外< U fs脉冲的鲁棒锁模光纤激光源，我们探索了二次（chi((2))）非线性光学过程，导致在整个中红外大气窗口中产生频率梳。通过实验和建模，我们展示了脉冲内差频产生，在单次通过周期性极化铌酸锂时产生几个周期的中红外脉冲。谐波和级联chi（(2)）非线性进一步提供了对近红外驱动脉冲序列的载波包络偏移频率的直接访问。中红外频率梳的高频稳定性被用于丙酮和羰基硫化物的光谱分析，其同时带宽超过11太赫兹，光谱分辨率高达0.003 cm（-1）。低噪声和广谱覆盖的结合使检测浓度在十亿分之一范围内的微量气体成为可能。
The mid-infrared atmospheric window of 3-5.5 mu m holds valuable information regarding molecular composition and function for fundamental and applied spectroscopy. Using a robust, mode-locked fiberlaser source of < U fs pulses in the near infrared, we explore quadratic (chi((2))) nonlinear optical processes leading to frequency comb generation across this entire mid-infrared atmospheric window. With experiments and modeling, we demonstrate intrapulse difference frequency generation that yields few-cycle mid-infrared pulses in a single pass through periodically poled lithium niobate. Harmonic and cascaded chi((2)) nonlinearities further provide direct access to the carrier-envelope offset frequency of the near infrared driving pulse train. The high frequency stability of the mid-infrared frequency comb is exploited for spectroscopy of acetone and carbonyl sulfide with simultaneous bandwidths exceeding 11 THz and with spectral resolution as high as 0.003 cm(-1). The combination of low noise and broad spectral coverage enables detection of trace gases with concentrations in the part-per-billion range.