Note: A simple multi-channel optical system for modulation spectroscopies

Area of Science:

• Materials Science
• Spectroscopy
• Optical Physics

Background:

• Photoreflectance-difference (PRD) and reflectance-difference (RD) spectroscopies are crucial for material characterization.
• Conventional methods typically rely on lock-in amplifiers operating at specific modulation frequencies.

Purpose of the Study:

• To develop and present a new measurement system for PRD and RD spectroscopies.
• To demonstrate an alternative approach that avoids the use of lock-in amplifiers.

Main Methods:

• Utilized a multichannel CCD spectrometer for data acquisition.
• Employed numerical subtraction between multiple CCD captures with and without a photoelastic modulator.
• Applied Savitzky-Golay filtering for spectral processing.

Main Results:

• Successfully acquired PRD and RD spectra without a lock-in amplifier.
• The proposed system is compatible with the slow response of CCD detectors to high modulation frequencies.
• The obtained spectra show good agreement with those measured using conventional lock-in amplifier systems.

Conclusions:

• The developed CCD-based system offers a viable alternative for PRD and RD spectroscopy.
• This approach simplifies experimental setup and is suitable for high modulation frequencies.
• The findings pave the way for more accessible and efficient optical characterization techniques.