Ultraviolet astronomical spectrograph calibration with laser frequency combs from nanophotonic lithium niobate waveguides

• Published in: Nature communications Vol. 15; no. 1; pp. 7614 - 11
• Main Authors: Ludwig, Markus, Ayhan, Furkan, Schmidt, Tobias M, Wildi, Thibault, Voumard, Thibault, Blum, Roman, Ye, Zhichao, Lei, Fuchuan, Wildi, François, Pepe, Francesco, Gaafar, Mahmoud A, Obrzud, Ewelina, Grassani, Davide, Hefti, Olivia, Karlen, Sylvain, Lecomte, Steve, Moreau, François, Chazelas, Bruno, Sottile, Rico, Torres-Company, Victor, Brasch, Victor, Villanueva, Luis G, Bouchy, François, Herr, Tobias
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 02.09.2024; Nature Publishing Group UK; Nature Portfolio
• Subjects: Astronomical instruments; Calibration; Extrasolar planets; Harmonic generations; Infrared astronomy; Infrared lasers; Lasers; Lithium; Lithium niobates; Near infrared radiation; Physical properties; Spectrographs; Spectroscopy; Spectrum analysis; Ultraviolet astronomy; Ultraviolet spectroscopy; Waveguides
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-51560-x

Abstract Astronomical precision spectroscopy underpins searches for life beyond Earth, direct observation of the expanding Universe and constraining the potential variability of physical constants on cosmological scales. Laser frequency combs can provide the required accurate and precise calibration to the astronomical spectrographs. For cosmological studies, extending the calibration with such astrocombs to the ultraviolet spectral range is desirable, however, strong material dispersion and large spectral separation from the established infrared laser oscillators have made this challenging. Here, we demonstrate astronomical spectrograph calibration with an astrocomb in the ultraviolet spectral range below 400 nm. This is accomplished via chip-integrated highly nonlinear photonics in periodically-poled, nano-fabricated lithium niobate waveguides in conjunction with a robust infrared electro-optic comb generator, as well as a chip-integrated microresonator comb. These results demonstrate a viable route towards astronomical precision spectroscopy in the ultraviolet and could contribute to unlock the full potential of next-generation ground-based and future space-based instruments.