Abstract
We present an oscillator-driven femtosecond transient microspectroscopy system based on supercontinuum generation in a photonic crystal fiber (PCF). The system operates at 80 MHz without pulse amplification, enabling high-sensitivity measurements with an RMS noise level below 10
−4
at 500–800 nm spectral range while using low pulse energies suitable for microspectroscopy. Optimization of the PCF length (50 mm) suppresses dispersion-induced chirp, achieving a nearly uniform system response over 450–900 nm, which allows time constants below 100 fs to be resolved by deconvolution. The high-repetition-rate operation allows rapid spectral acquisition and efficient noise reduction. The developed system provides single-μm scale spatial resolution and supports both reflection and transmission configurations. The ultrafast carrier dynamics in multilayer and monolayer MoS
2
are successfully resolved, including spatially dependent relaxation within a single monolayer flake. These results demonstrate a versatile platform for probing local ultrafast dynamics in low-dimensional materials.