Broadband rapid-scanning phase-modulated Fourier transform electronic spectroscopy

Area of Science:

• Spectroscopy
• Quantum Optics
• Biophysics

Background:

• Acousto-optic modulators (AOMs) introduce bandwidth limitations and spatial chirp in ultrabroadband spectroscopy.
• Existing Fourier transform electronic spectroscopy methods struggle with low-frequency noise and limited spectral resolution.
• Phase modulation is crucial for advanced spectroscopic techniques but challenging to implement broadly.

Purpose of the Study:

• To present a phase-modulated approach for ultrabroadband Fourier transform electronic spectroscopy.
• To overcome bandwidth limitations and spatial chirp associated with acousto-optic modulators (AOMs).
• To enable continuous, rapid-scanning spectroscopy with high signal-to-noise ratio and spectral resolution.

Main Methods:

• Utilizing phase modulation of 1 µm laser pulses prior to continuum generation in a yttrium aluminum garnet crystal.
• Employing a Mach-Zehnder interferometer to interfere phase-modulated continua with differing modulation frequencies.
• Implementing physical under-sampling and low-frequency noise suppression through interferometric tracking of relative time delays.

Main Results:

• Successfully transferred phase modulation to the generated continuum.
• Achieved physical under-sampling and suppressed low-frequency noise.
• Demonstrated continuous, rapid-scanning Fourier transform electronic spectroscopy with high signal-to-noise ratio and spectral resolution.

Conclusions:

• The phase-modulated approach effectively overcomes limitations of traditional acousto-optic modulators (AOMs).
• This technique enables high-performance ultrabroadband Fourier transform electronic spectroscopy.
• The method was validated by measuring linear absorption and fluorescence excitation spectra of laser dyes and biological samples.