Time-stretched real-time measurement technique for ultrafast absorption variations with TS/s sampling-rate

Area of Science:

• Optics and Photonics
• Materials Science
• Ultrafast Spectroscopy

Background:

• Ultrafast absorption variations are crucial in fields like semiconductor physics and material processing.
• Conventional pump-probe experiments offer high resolution but lack real-time capabilities for dynamic events.

Purpose of the Study:

• To develop and demonstrate a real-time measurement technique for ultrafast absorption dynamics.
• To achieve high sampling rates (up to 1.1 TS/s) for capturing transient optical phenomena.
• To validate the technique by comparing results with established methods.

Main Methods:

• Utilizing a resonator-based time-stretch system with a variable stretch factor (up to 13.8).
• Employing a single-shot data capture within an 800 ps time window and a 10 MHz update rate.
• Implementing an adapted optical backpropagation algorithm for signal reconstruction.

Main Results:

• Successfully measured the temporal dynamics of a picosecond semiconductor saturable absorber mirror in real-time.
• Demonstrated excellent agreement between the time-stretch technique's results and conventional pump-probe measurements.
• Achieved a sampling rate of up to 1.1 Terabytes per second (TS/s).

Conclusions:

• The developed time-stretch technique provides a viable method for real-time measurement of ultrafast absorption dynamics.
• This technique has broad applicability for studying phenomena such as semiconductor charge carrier dynamics and polymerization processes.
• Offers a powerful alternative for investigating dynamic changes in saturable absorber materials.