Imaging Fourier spectrometer in visible domain: experimental results

Area of Science:

• Spectroscopy
• Optical Engineering
• Photonics

Background:

• Compact imaging Fourier spectrometers are crucial for various applications.
• High-frequency optical signal detection presents challenges.
• Molecular transition decay time measurements require sensitive instrumentation.

Purpose of the Study:

• To report the performance of a prototype compact imaging Fourier spectrometer for the visible domain.
• To evaluate its capabilities in high-frequency applications and spectral selectivity.
• To demonstrate its sensitivity to low optical flux.

Main Methods:

• Utilized a photo-multiplying tube for optical signal recording in high-frequency applications (up to 100 MHz).
• Experimentally demonstrated selectivity for spectra modulated at 100 kHz against background light.
• Measured molecular transition decay times of 50 ns.

Main Results:

• The imaging Fourier spectrometer showed 10 times higher sensitivity than compact grating spectrometers for line-type spectra.
• This sensitivity advantage diminished for smooth spectra with short coherence lengths.
• Achieved a sensitivity as low as 6⋅10^-13 W/m² in the visible and near-infrared domains.

Conclusions:

• The prototype compact imaging Fourier spectrometer performs effectively in the visible domain.
• It offers superior sensitivity for specific spectral types and fast temporal measurements.
• The device shows promise for applications requiring detection of very low optical fluxes.