Spectral envelope control for a flat frequency comb spectrum

Abstract

Laser frequency combs have properties which make them promising spectrograph calibration light sources. One drawback for this application is the high dynamic range in the supercontinuum spectra of some frequency combs. We aim to flatten the spectrum of a Ti:sapphire laser frequency comb to improve the calibration performance for a Fourier transform spectrograph. For this, we develop a compact Fourier transform optical pulse shaping setup, which enables control of the spectral envelope via dispersion of the light onto a spatial light modulator. We demonstrate, that this setup allows us to flatten the comb spectrum from a dynamic range of 20 dB to less than 6 dB in the wavelength range 739-939 nm. For 86 % of the wavelength range, the dynamic range is below 1 dB.