We describe a new method to broaden the frequency spectrum of a femtosecond oscillator in the continuous-wave (CW) domain. The method relies on modulating the femtosecond laser using four-wave mixing inside a Raman-based optical modulator. We prepare the modulator by placing deuterium molecules inside a high-finesse cavity and driving their fundamental vibrational transition using intense pump and Stokes lasers that are locked to the cavity modes. With the molecules prepared, any laser within the optical region of the spectrum can pass through the system and be modulated in a single pass. This constitutes a CW optical modulator at a frequency of 90 THz with a steady-state single-pass efficiency of $\sim {10}^{-6}$ and transient (10 μs-time-scale) single-pass efficiency of $\sim {10}^{-4}$. Using our modulator, we broaden the initial Ti:sapphire spectrum centered at 800 nm and produce upshifted and downshifted sidebands centered at wavelengths of 650 nm and 1.04 μm, respectively.

中文翻译：

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使用相干分子对飞秒振荡器进行连续波调制

我们描述了一种在连续波（CW）域中拓宽飞秒振荡器频谱的新方法。该方法依赖于在基于拉曼的光学调制器内部使用四波混频来调制飞秒激光器。我们通过将氘分子放置在高精细腔中并使用锁定在腔模式下的强泵浦和斯托克斯激光器驱动其基本振动跃迁来制备调制器。制备好分子后，光谱光学区域内的任何激光都可以通过系统，并在一次通过中被调制。这构成了频率为90 THz的CW光调制器，其稳态单通效率为$〜{10}^{-6}$ 和瞬态（10μs时标）单通效率 $〜{10}^{-4}$。使用我们的调制器，我们拓宽了以800 nm为中心的初始Ti：蓝宝石光谱，并分别产生了以650 nm和1.04μm的波长为中心的上移和下移的边带。