High-sensitivity pump-probe spectroscopy with a dual-comb laser and a PM-Andi supercontinuum

Area of Science:

• Ultrafast spectroscopy
• Materials science
• Photovoltaics

Background:

• Traditional amplifier-based pump-probe systems face challenges with complexity and speed, particularly for low-fluence excitation.
• Investigating excited-state dynamics is crucial for optimizing materials used in advanced technologies like solar cells.

Purpose of the Study:

• To introduce a novel, high-speed, and sensitive pump-probe system overcoming limitations of existing methods.
• To characterize the wavelength-dependent excited-state dynamics of the non-fullerene acceptor Y6 at low excitation fluences.

Main Methods:

• Utilized a 60-MHz single-cavity dual-comb oscillator and an ultra-low noise supercontinuum.
• Operated the system in equivalent time sampling and programmable optical delay generation modes.
• Achieved shot-noise limited sensitivity in differential transmission measurements.

Main Results:

• Successfully studied the excited-state dynamics of Y6 with excitation fluences as low as 1 nJ/cm².
• Demonstrated a differential transmission sensitivity of 3.4·10^-7.
• Confirmed the system's capability to probe dynamics below nonlinear exciton annihilation thresholds.

Conclusions:

• The developed dual-comb pump-probe system offers enhanced speed and sensitivity for ultrafast spectroscopy.
• This technology enables precise investigation of material dynamics at ultralow excitation levels, advancing solar cell research.
• The system holds significant potential for broader applications in ultrafast science.