Searching for Exoplanets Using a Microresonator Astrocomb

TL;DR

This paper demonstrates the use of a chip-based Kerr soliton microcomb for calibrating astronomical spectrographs to detect exoplanets via radial velocity shifts, showing promising field application at the Keck-II telescope.

Contribution

It introduces a novel, chip-based microcomb device for astronomical calibration and reports the first in-field exoplanet search using this technology.

Findings

Successful demonstration of microcomb calibration at Keck-II

First in-field exoplanet search using microcombs

Potential for space-borne spectrograph calibration

Abstract

Detection of weak radial velocity shifts of host stars induced by orbiting planets is an important technique for discovering and characterizing planets beyond our solar system. Optical frequency combs enable calibration of stellar radial velocity shifts at levels required for detection of Earth analogs. A new chip-based device, the Kerr soliton microcomb, has properties ideal for ubiquitous application outside the lab and even in future space-borne instruments. Moreover, microcomb spectra are ideally suited for astronomical spectrograph calibration and eliminate filtering steps required by conventional mode-locked-laser frequency combs. Here, for the calibration of astronomical spectrographs, we demonstrate an atomic/molecular line-referenced, near-infrared soliton microcomb. Efforts to search for the known exoplanet HD 187123b were conducted at the Keck-II telescope as a first in-the-field demonstration of microcombs.