Multidimensional coherent photocurrent spectroscopy of a semiconductor nanostructure

Area of Science:

• Physical Sciences
• Spectroscopy
• Semiconductor Physics

Background:

• Coherent optical spectroscopy provides insights into material properties.
• Traditional methods often require active stabilization, increasing complexity.
• Photocurrent detection offers a sensitive probe of electronic transitions.

Purpose of the Study:

• To implement Multidimensional Coherent Optical Photocurrent Spectroscopy (MD-COPS) using unstabilized interferometers.
• To develop a robust method for phase-stable photocurrent measurements.
• To demonstrate the application of MD-COPS for studying excitonic resonances.

Main Methods:

• Utilized a collinear geometry with four frequency-shifted excitation pulses.
• Employed acousto-optical modulation for radio frequency shifting.
• Synthesized reference frequencies using an auxiliary continuous wave laser for lock-in detection.
• Selected the Four-Wave Mixing (FWM) signal in the frequency domain.

Main Results:

• Achieved sufficient phase stability without active mechanical stabilization.
• Acquired both real and imaginary parts of the FWM signal as a function of inter-pulse delays.
• Generated multidimensional spectra via Fourier transformation.
• Successfully measured the excitonic resonance in a double InGaAs quantum well.

Conclusions:

• MD-COPS is a viable technique for semiconductor characterization.
• The method offers enhanced phase stability and detailed spectral information.
• Demonstrated the utility of MD-COPS for probing excitonic phenomena in quantum wells.