Publication

Astronomical spectrograph calibration with ultraviolet astrocombs

2024

Abstract

Precision astronomical spectroscopy is vital for seeking life beyond Earth and often relies on detecting very small wavelength shifts over years. Precision of these instruments are ensured by regular wavelength calibration and laser frequency combs stabilized with frequency standards have recently emerged as suitable sources. In this work, we demonstrate wavelength calibration of an astronomical spectrograph in ultraviolet spectrum below 400 nm. This is achieved using second- and third- order nonlinear effects in thin-film, periodically poled lithium niobate waveguides with an infrared electro-optic comb generator at 18 GHz.

Official source

https://infoscience.epfl.ch/entities/publication/1bf5cae3-9298-4142-81e4-656cd8e8b925

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2024

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/1bf5cae3-9298-4142-81e4-656cd8e8b925

About this result

Related concepts (32)

Frequency comb

In optics, a frequency comb is a laser source whose spectrum consists of a series of discrete, equally spaced frequency lines. Frequency combs can be generated by a number of mechanisms, including periodic modulation (in amplitude and/or phase) of a continuous-wave laser, four-wave mixing in nonlinear media, or stabilization of the pulse train generated by a mode-locked laser. Much work has been devoted to this last mechanism, which was developed around the turn of the 21st century and ultimately led to one half of the Nobel Prize in Physics being shared by John L.

Nonlinear optics

Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in nonlinear media, that is, media in which the polarization density P responds non-linearly to the electric field E of the light. The non-linearity is typically observed only at very high light intensities (when the electric field of the light is >108 V/m and thus comparable to the atomic electric field of ~1011 V/m) such as those provided by lasers. Above the Schwinger limit, the vacuum itself is expected to become nonlinear.

Visible spectrum

The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 380 to about 700 nanometers. In terms of frequency, this corresponds to a band in the vicinity of 400–790 terahertz. These boundaries are not sharply defined and may vary per individual. Under optimal conditions these limits of human perception can extend to 310 nm (ultraviolet) and 1100 nm (near infrared).