Fig. 1: Ultraviolet astronomical precision spectroscopy. | Nature Communications

Fig. 1: Ultraviolet astronomical precision spectroscopy.

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

Fig. 1

a Precision spectroscopy of astronomical objects enabled by laser frequency combs (LFC) providing absolutely and precisely known laser frequencies, cf. main text. QSO: quasi-stellar object, H, H2: hydrogen, D: deuterium, P: optical power. b Atmospheric transmission (high altitude, dry), spectral ranges for different astrophysical studies. c Expected redshift drift signal for the standard ΛCDM cosmology89 in units of cm/s per decade (Sandage test) as a function of wavelength, corresponding to the redshifted H I Lyα transition. d Concept of broadening and transferring a high-repetition-rate astrocomb from infrared (IR) to visible (VIS) and ultraviolet (UV) wavelengths based on optical χ(2)- and χ(3)-nonlinearities.

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