标题： 双太赫兹梳光谱与单个自由运行光纤激光器 显示英文标题

标题： Dual terahertz comb spectroscopy with a single free-running fibre laser

摘要： 双太赫兹梳光谱技术有潜力作为通用太赫兹光谱技术，具有高光谱分辨率、高光谱精度和宽光谱覆盖范围；然而，对双稳频飞秒激光器的要求限制了其通用性，因为体积庞大、结构复杂且成本高昂。 我们在这里首次展示了使用单个自由运行光纤激光器的双太赫兹梳光谱技术。 通过在腔内使用Lyot滤波器调节腔损耗依赖的增益轮廓，并精确管理腔长和色散，可在单一激光腔中生成略微失谐重复频率的双波长脉冲光束。 由于共享同一腔体，这些脉冲光束会受到重复频率的共模波动影响，因此它们之间的对应频率差在毫赫兹波动范围内被动稳定在几百赫兹左右。 这种高度稳定的频率差使得使用单个自由运行光纤激光器进行双太赫兹梳光谱成为可能。 虽然使用单个自由运行光纤激光器大大减小了激光源的体积、复杂性和成本，但双太赫兹梳光谱系统保持了与配备双稳频光纤激光器的系统相当的光谱带宽和光谱功率动态范围，并可有效应用于大气压下乙腈气体的高精度光谱分析。 所展示的结果表明，该系统不仅适用于太赫兹光谱的实际应用，也适用于基于太赫兹脉冲的测量。 显示英文摘要

摘要： Dual THz comb spectroscopy has the potential to be used as universal THz spectroscopy with high spectral resolution, high spectral accuracy, and broad spectral coverage; however, the requirement for dual stabilized femtosecond lasers hampers its versatility due to the bulky size, high complexity, and high cost. We here report the first demonstration of dual THz comb spectroscopy using a single free-running fibre laser. By tuning the cavity-loss-dependent gain profile with an intracavity Lyot filter together with precise management of the cavity length and dispersion, dual-wavelength pulsed light beams with slightly detuned repetition frequencies are generated in a single laser cavity. Due to sharing of the same cavity, such pulsed light beams suffer from common-mode fluctuation of the repetition frequency, and hence the corresponding frequency difference between them is passively stable around a few hundred hertz within millihertz fluctuation. This considerably stable frequency difference enables dual THz comb spectroscopy with a single free-running fibre laser. While greatly reducing the size, complexity, and cost of the laser source by use of a single free-running fibre laser, the dual THz comb spectroscopy system maintains a spectral bandwidth and dynamic range of spectral power comparable to a system equipped with dual stabilized fibre lasers, and can be effectively applied to high-precision spectroscopy of acetonitrile gas at atmospheric pressure. The demonstrated results indicate that this system is an attractive solution for practical applications of not only THz spectroscopy but also THz-pulse-based measurements.