Stimulated Raman scattering (SRS) has been developed as an essential quantitative contrast for chemical imaging in recent years. However, while spectral lines near the natural linewidth limit can be routinely achieved by state-of-the-art spontaneous Raman microscopes, spectral broadening is inevitable for current mainstream SRS imaging methods. This is because those SRS signals are all measured in the frequency domain. There is a compromise between sensitivity and spectral resolution: as the nonlinear process benefits from pulsed excitations, the fundamental time-energy uncertainty limits the spectral resolution. Besides, the spectral range and acquisition speed are mutually restricted. Here we report transient stimulated Raman scattering (T-SRS), an alternative time-domain strategy that bypasses all these fundamental conjugations. T-SRS is achieved by quantum coherence manipulation: we encode the vibrational oscillations in the stimulated Raman loss (SRL) signal by femtosecond pulse-pair sequence excited vibrational wave packet interference. The Raman spectrum was then achieved by Fourier transform of the time-domain SRL signal. Since all Raman modes are impulsively and simultaneously excited, T-SRS features the natural-linewidth-limit spectral line shapes, laser-bandwidth-determined spectral range, and improved sensitivity. With ~150-fs laser pulses, we boost the sensitivity of typical Raman modes to the sub-mM level. With all-plane-mirror high-speed time-delay scanning, we further demonstrated hyperspectral SRS imaging of live-cell metabolism and high-density multiplexed imaging with the natural-linewidth-limit spectral resolution. T-SRS shall find valuable applications for advanced Raman imaging.

近年来，受激拉曼散射（SRS）已发展成为化学成像的重要定量对比。然而，虽然最先进的自发拉曼显微镜通常可以实现接近自然线宽极限的谱线，但对于当前主流的 SRS 成像方法来说，光谱展宽是不可避免的。这是因为这些 SRS 信号都是在频域中测量的。灵敏度和光谱分辨率之间存在折衷：由于非线性过程受益于脉冲激励，基本的时间-能量不确定性限制了光谱分辨率。此外，光谱范围和采集速度是相互制约的。在这里，我们报告瞬态受激拉曼散射（T-SRS），这是一种绕过所有这些基本共轭的替代时域策略。T-SRS 是通过量子相干操纵实现的：我们通过飞秒脉冲对序列激发振动波包干涉对受激拉曼损耗 (SRL) 信号中的振动振荡进行编码。然后通过时域 SRL 信号的傅里叶变换获得拉曼光谱。由于所有拉曼模式都是脉冲同时激发的，因此 T-SRS 具有自然线宽极限谱线形状、激光带宽确定的光谱范围和改进的灵敏度。利用 ~150-fs 激光脉冲，我们将典型拉曼模式的灵敏度提高到亚毫米级。通过全平面镜高速延时扫描，我们进一步证明了活细胞代谢的高光谱SRS成像和具有自然线宽极限光谱分辨率的高密度多重成像。T-SRS 将为先进拉曼成像找到有价值的应用。