Broadening of femtosecond frequency combs and compact optical to radio frequency conversion

Summary form only given. The periodic pulse train emitted by a modelocked femtosecond laser can be viewed in the frequency domain as a comb of equidistant modes spaced by the pulse repetition rate. This broad frequency comb can be used like a ruler to phase coherently measure large differences between laser frequencies. With our Kerr-lens mode-locked Ti:sapphire laser (pulselength 73 fs, Coherent Inc., model Mira 900) we have shown that the modes of the femtosecond frequency comb are distributed uniformly in frequency space within the experimental limit.