Single-Cavity Dual-Comb Fiber Laser Enabled Pump-Probe Microscopy

Abstract

Pump-probe technique is an important spectroscopic method for characterizing photocarrier dynamics in semiconductors. When combined with fast scanning mechanisms, pump-probe spectroscopy can yield spatially relevant information and is highly desirable for advanced characterization of materials. A conventional pump-probe microscopy system requires an optical delay-line to vary the time delay between the pump and the probe pulses, which poses a significant bottleneck for the imaging speed. Thanks to the method of asynchronous optical sampling, the data acquisition speed in a pump-probe measurement can be dramatically improved by using dual-comb light sources. However, commercially available dual-comb sources are bulky systems with complicated stabilization mechanisms, making their wide use in pump-probe imaging systems a challenge. In this letter, we demonstrate a pump-probe microscopy system enabled by a single-cavity dual-comb Er-doped fiber laser for the first time. The single-point data acquisition time is reduced to less than 6 ms. By using this single-cavity dual-comb source, an InGaAs quantum-well sample with millimeter lateral dimension has been characterized, and meaningful images showing surface defective sites are clearly presented. These results provide a new solution for fast and cost-effective pump-probe imaging systems.