Achromatic optical device for generation of a broadband frequency spectrumwith high-frequency stability and sharp termination

We have implemented a new optical scheme to produce a broadband frequency s pectrum with customizable shape and high stability. The scheme consists of the generation of a mode structure by allowing a frequency-stabilized singl e-mode laser to pass through an acousto-optical modulator working in the Ra man-Nath regime. Diffraction yields several diffracted beams, which are shi fted in frequency (Deltav(M)) by acoustic waves in the acousto-optical modu lator. Then the diffracted beams are merged into one beam by means of a tel escope. The scheme has worked in both the visible and the UV: Frequency spe ctra as wide as n Deltav(M) with n = 7 have been achieved, resulting in wid ths of 225 and 150 MHz for the visible and the UV spectral regions, respect ively. The spectra possess the same stability as the primary single-mode la ser. Their profiles may exhibit a sharp termination on one side of the spec trum, a feature that allows them to be utilized for high-efficiency laser c ooling of an ion beam in a storage ring. (C) 2001 Optical Society of Americ a.