Open AccessAccurate phase detection in time-domain heterodyne SFG spectroscopy
Author(s) -
Nasim Mirzajani,
Clare L. Keenan,
Sarah Melton,
Sarah King
Publication year - 2022
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.473098
Subject(s) - optics , spectrometer , local oscillator , interferometry , heterodyne detection , heterodyne (poetry) , spectroscopy , phase modulation , phase (matter) , phase noise , physics , fourier transform spectroscopy , laser , fourier transform infrared spectroscopy , quantum mechanics , acoustics
Heterodyne detection is a ubiquitous tool in spectroscopy for the simultaneous detection of intensity and phase of light. However, the need for phase stability hinders the application of heterodyne detection to electronic spectroscopy. We present an interferometric design for a phase-sensitive electronic sum frequency generation (e-SFG) spectrometer in the time domain with lock-in detection. Our method of continuous phase modulation of one arm of the interferometer affords direct measurement of the phase between SFG and local oscillator fields. Errors in the path length difference caused by drifts in the optics are corrected, offering unprecedented stability. This spectrometer has the added advantage of collinear fundamental beams. The capabilities of the spectrometer are demonstrated with proof-of-principle experiments with GaAs e-SFG spectra, where we see significantly improved signal to noise ratio, spectral accuracy, and lineshapes.