Echelle spectrograph calibration with a frequency comb based on a harmonically mode-locked fiber laser: a proposal

Journal Article · Sun May 10 04:00:00 EDT 2009 · Applied Optics

DOI:https://doi.org/10.1364/AO.48.002752· OSTI ID:22036366

McFerran, J J

Details for constructing an astronomical frequency comb suitable as a wavelength reference for echelle spectrographs associated with optical telescopes are outlined. The source laser for the frequency comb is a harmonically mode-locked fiber laser with a central wavelength of 1.56 {mu}m. The means of producing a repetition rate greater than 7 GHz and a peak optical power of {approx}8 kW are discussed. Conversion of the oscillator light into the visible can occur through a two-step process of (i) nonlinear conversion in periodically poled lithium niobate and (ii) spectral broadening in photonic crystal fiber. While not necessarily octave spanning in spectral range to permit the use of an f -to- 2f interferometer for offset frequency control, the frequency comb can be granted accuracy by linking the mode spacing and a comb tooth to separate frequency references. The design avoids the use of a Fabry-Perot cavity to increase the mode spacing of the frequency comb; however, the level of supermode suppression and sideband asymmetry in the fiber oscillator and in the subsequent frequency conversion stages are aspects that need to be experimentally tested.

• OSTI ID: 22036366
• Journal Information: Applied Optics, Journal Name: Applied Optics Journal Issue: 14 Vol. 48; ISSN 0003-6935; ISSN APOPAI
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACCURACY
ASYMMETRY
CALIBRATION
CAVITIES
CONVERSION
CRYSTALS
DIFFRACTION GRATINGS
FIBERS
FREQUENCY CONTROL
INTERFEROMETERS
LASER RADIATION
LINE BROADENING
LITHIUM
MODE LOCKING
NIOBATES
NONLINEAR PROBLEMS
PERIODICITY
SPECTROMETERS
VISIBLE RADIATION
WAVELENGTHS