Extended Data Fig. 4: Sensitive mapping of microbial activity by picosecond SRS.
From: The Parkinson’s disease drug entacapone disrupts gut microbiome homeostasis via iron sequestration
a. Picosecond SRS alleviates cross-phase modulation (XPM) and provides higher sensitivity for measuring the activity of microbial cells via deuterium incorporation with a laser power below the cell-damaging threshold. Picosecond SRS pump power: 30 mW, Stokes power: 120 mW. Femtosecond SRS: pump power: 15 mW, Stokes power: 70 mW. We reproducibly detected analogous differences when measuring at least one additional batch of samples. b. Picosecond and femtosecond SRS probing difference in the spectral domain. For picosecond SRS, the targeting bandwidth is 20 cm−1, which is much narrower than the femtosecond SRS which covers more than 200 cm−1. Thus, the ratio between the signal (vibrational feature) and the background (cross phase modulation, XPM) is improved in picosecond SRS.
