  Laser cooling of atoms usually necessitates several laser frequencies.
Alkaline atoms, for example, are cooled by two lasers with a frequency
difference in the Gigahertz range. This gap cannot be closed with simple
shifting techniques. Here, we present a method of generating sidebands at 6.6
GHz by modulating the current of a tapered amplifier which is seeded by an
unmodulated master laser. The sidebands enable trapping of 1.1*10^9 Rubidium 87
atoms in a chip-based magneto-optical trap. Compared to the direct modulation
of the master laser, this method allows for an easy implementation, a fast
adjustment over a wide frequency range and the simultaneous extraction of
unmodulated light for manipulation and detection. The low power consumption,
small size and applicability for multiple frequencies benefits a wide range of
applications, reaching from atom-based mobile sensors to the laser cooling of
molecules.
