Self-calibrated Fourier transform spectrometer for laser-induced fluorescence spectroscopy with single-photon...

Area of Science:

• Spectroscopy
• Optical Engineering
• Laser Technology

Background:

• Fourier transform spectrometers offer high signal-to-noise ratios but face challenges in laser-induced fluorescence (LIF) applications.
• Single-photon avalanche diodes (SPADs) enhance sensitivity but can cause detector saturation and long acquisition times in LIF.

Purpose of the Study:

• To develop a Fourier transform spectrometer capable of simultaneously detecting LIF signals and excitation light.
• To implement a self-calibration method using the second harmonic of the excitation light, eliminating the need for external calibration sources.

Main Methods:

• A Fourier transform spectrometer was designed to detect both LIF and excitation light.
• The second harmonic signal generated from the excitation light was utilized for phase correction and spectral calibration.
• Performance was evaluated based on spectral resolution, sensitivity, and noise floor.

Main Results:

• Achieved a spectral resolution of 0.4 cm⁻¹ at 1140.2 nm.
• Demonstrated detection of signals as low as 377 fW.
• Established a noise floor of 172 fW/cm⁻¹.

Conclusions:

• The developed spectrometer effectively detects LIF signals with high sensitivity and resolution.
• The self-calibration method simplifies experimental setup and improves accuracy in LIF applications.
• This approach overcomes limitations associated with SPAD detectors in LIF spectroscopy.