"Modal noise" in single-mode fibers

A cautionary note for high precision radial velocity instruments

Samuel Halverson, Arpita Roy, Suvrath Mahadevan, Christian Schwab

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Exploring the use of single-mode fibers (SMFs) in high precision Doppler spectrometers has become increasingly attractive since the advent of diffraction-limited adaptive optics systems on large-aperture telescopes. Spectrometers fed with these fibers can be made significantly smaller than typical "seeing-limited" instruments, greatly reducing cost and overall complexity. Importantly, classical mode interference and speckle issues associated with multi-mode fibers, also known as "modal noise," are mitigated when using SMFs, which also provide perfect radial and azimuthal image scrambling. However, SMFs do support multiple polarization modes, an issue that is generally ignored for larger-core fibers given the large number of propagation modes. Since diffraction gratings used in most high resolution astronomical instruments have dispersive properties that are sensitive to incident polarization changes, any birefringence variations in the fiber can cause variations in the efficiency profile, degrading illumination stability. Here we present a cautionary note outlining how the polarization properties of SMFs can affect the radial velocity (RV) measurement precision of high resolution spectrographs. This work is immediately relevant to the rapidly expanding field of diffraction-limited, extreme precision RV spectrographs that are currently being designed and built by a number of groups.

Original languageEnglish (US)
Article numberL22
JournalAstrophysical Journal Letters
Volume814
Issue number2
DOIs
StatePublished - Dec 1 2015

Fingerprint

radial velocity
fibers
diffraction
polarization
spectrographs
spectrometer
spectrometers
birefringence
propagation modes
fibre
high resolution
speckle
gratings (spectra)
adaptive optics
velocity measurement
apertures
illumination
telescopes
costs
interference

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

@article{5b0b52d94d5844f0a257accc2e84016f,
title = "{"}Modal noise{"} in single-mode fibers: A cautionary note for high precision radial velocity instruments",
abstract = "Exploring the use of single-mode fibers (SMFs) in high precision Doppler spectrometers has become increasingly attractive since the advent of diffraction-limited adaptive optics systems on large-aperture telescopes. Spectrometers fed with these fibers can be made significantly smaller than typical {"}seeing-limited{"} instruments, greatly reducing cost and overall complexity. Importantly, classical mode interference and speckle issues associated with multi-mode fibers, also known as {"}modal noise,{"} are mitigated when using SMFs, which also provide perfect radial and azimuthal image scrambling. However, SMFs do support multiple polarization modes, an issue that is generally ignored for larger-core fibers given the large number of propagation modes. Since diffraction gratings used in most high resolution astronomical instruments have dispersive properties that are sensitive to incident polarization changes, any birefringence variations in the fiber can cause variations in the efficiency profile, degrading illumination stability. Here we present a cautionary note outlining how the polarization properties of SMFs can affect the radial velocity (RV) measurement precision of high resolution spectrographs. This work is immediately relevant to the rapidly expanding field of diffraction-limited, extreme precision RV spectrographs that are currently being designed and built by a number of groups.",
author = "Samuel Halverson and Arpita Roy and Suvrath Mahadevan and Christian Schwab",
year = "2015",
month = "12",
day = "1",
doi = "10.1088/2041-8205/814/2/L22",
language = "English (US)",
volume = "814",
journal = "Astrophysical Journal Letters",
issn = "2041-8205",
publisher = "IOP Publishing Ltd.",
number = "2",

}

"Modal noise" in single-mode fibers : A cautionary note for high precision radial velocity instruments. / Halverson, Samuel; Roy, Arpita; Mahadevan, Suvrath; Schwab, Christian.

In: Astrophysical Journal Letters, Vol. 814, No. 2, L22, 01.12.2015.

Research output: Contribution to journalArticle

TY - JOUR

T1 - "Modal noise" in single-mode fibers

T2 - A cautionary note for high precision radial velocity instruments

AU - Halverson, Samuel

AU - Roy, Arpita

AU - Mahadevan, Suvrath

AU - Schwab, Christian

PY - 2015/12/1

Y1 - 2015/12/1

N2 - Exploring the use of single-mode fibers (SMFs) in high precision Doppler spectrometers has become increasingly attractive since the advent of diffraction-limited adaptive optics systems on large-aperture telescopes. Spectrometers fed with these fibers can be made significantly smaller than typical "seeing-limited" instruments, greatly reducing cost and overall complexity. Importantly, classical mode interference and speckle issues associated with multi-mode fibers, also known as "modal noise," are mitigated when using SMFs, which also provide perfect radial and azimuthal image scrambling. However, SMFs do support multiple polarization modes, an issue that is generally ignored for larger-core fibers given the large number of propagation modes. Since diffraction gratings used in most high resolution astronomical instruments have dispersive properties that are sensitive to incident polarization changes, any birefringence variations in the fiber can cause variations in the efficiency profile, degrading illumination stability. Here we present a cautionary note outlining how the polarization properties of SMFs can affect the radial velocity (RV) measurement precision of high resolution spectrographs. This work is immediately relevant to the rapidly expanding field of diffraction-limited, extreme precision RV spectrographs that are currently being designed and built by a number of groups.

AB - Exploring the use of single-mode fibers (SMFs) in high precision Doppler spectrometers has become increasingly attractive since the advent of diffraction-limited adaptive optics systems on large-aperture telescopes. Spectrometers fed with these fibers can be made significantly smaller than typical "seeing-limited" instruments, greatly reducing cost and overall complexity. Importantly, classical mode interference and speckle issues associated with multi-mode fibers, also known as "modal noise," are mitigated when using SMFs, which also provide perfect radial and azimuthal image scrambling. However, SMFs do support multiple polarization modes, an issue that is generally ignored for larger-core fibers given the large number of propagation modes. Since diffraction gratings used in most high resolution astronomical instruments have dispersive properties that are sensitive to incident polarization changes, any birefringence variations in the fiber can cause variations in the efficiency profile, degrading illumination stability. Here we present a cautionary note outlining how the polarization properties of SMFs can affect the radial velocity (RV) measurement precision of high resolution spectrographs. This work is immediately relevant to the rapidly expanding field of diffraction-limited, extreme precision RV spectrographs that are currently being designed and built by a number of groups.

UR - http://www.scopus.com/inward/record.url?scp=84949197254&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84949197254&partnerID=8YFLogxK

U2 - 10.1088/2041-8205/814/2/L22

DO - 10.1088/2041-8205/814/2/L22

M3 - Article

VL - 814

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

SN - 2041-8205

IS - 2

M1 - L22

ER -