Characterization of very narrow spectral lines with temporal intensity interferometry

Abstract

Context: Some stellar objects exhibit very narrow spectral lines in the visible range additional to their blackbody radiation. Natural lasing has been suggested as a mechanism to explain narrow lines in Wolf-Rayet stars. However, the spectral resolution of conventional astronomical spectrographs is still about two orders of magnitude too low to test this hypothesis. Aims: We want to resolve the linewidth of narrow spectral emissions in starlight. Methods: A combination of spectral filtering with single-photon-level temporal correlation measurements breaks the resolution limit of wavelength-dispersing spectrographs by moving the linewidth measurement into the time domain. Results: We demonstrate in a laboratory experiment that temporal intensity interferometry can determine a 20 MHz wide linewidth of Doppler-broadened laser light, and identify a coherent laser light contribution in a blackbody radiation background.

4 pages, 4 figures

References in corpus (5)

• A Wolf-Rayet-like progenitor of supernova SN 2013cu from spectral observations of a wind
• High-precision wavelength calibration of astronomical spectrographs with laser frequency combs
• Optical aperture synthesis with electronically connected telescopes
• Measuring Temporal Photon Bunching in Blackbody Radiation
• Optical Intensity Interferometry through Atmospheric Turbulence

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