The Keck Planet Imager and Characterizer: A dedicated single-mode fiber injection unit for high resolution exoplanet spectroscopy

TL;DR

The KPIC instrument at Keck combines adaptive optics and high-resolution spectroscopy using a single-mode fiber injection unit to enable detailed exoplanet characterization, including atmospheric and rotational properties.

Contribution

This paper introduces the design and calibration of a novel fiber injection unit for high-resolution exoplanet spectroscopy at Keck, demonstrating its capability for detailed planetary analysis.

Findings

Successful acquisition of high-resolution spectra of exoplanets and brown dwarfs

Demonstrated system performance and calibration procedures

Enabled measurements of planetary spin and atmospheric features

Abstract

The Keck Planet Imager and Characterizer (KPIC) is a purpose-built instrument to demonstrate new technological and instrumental concepts initially developed for the exoplanet direct imaging field. Located downstream of the current Keck II adaptive optic system, KPIC contains a fiber injection unit (FIU) capable of combining the high-contrast imaging capability of the adaptive optics system with the high dispersion spectroscopy capability of the current Keck high resolution infrared spectrograph (NIRSPEC). Deployed at Keck in September 2018, this instrument has already been used to acquire high resolution spectra ($R > 30,000$) of multiple targets of interest. In the near term, it will be used to spectrally characterize known directly imaged exoplanets and low-mass brown dwarf companions visible in the northern hemisphere with a spectral resolution high enough to enable spin and planetary radial velocity measurements as well as Doppler imaging of atmospheric weather phenomena. Here we present the design of the FIU, the unique calibration procedures needed to operate a single-mode fiber instrument and the system performance.