Optical arbitrary waveform processing of more than 100 spectral comb lines

Pulse-shaping techniques, in which user-specified, ultrashort-pulse fields are synthesized by means of parallel manipulation of optical Fourier components, have now been widely adopted(1-6). Mode-locked lasers producing combs of frequency-stabilized spectral lines have resulted in revolutionary advances in frequency metrology(7-11). However, until recently, pulse shapers addressed spectral lines in groups, at low spectral resolution. Line-by-line pulse shaping(12), in which spectral lines are resolved and manipulated individually, leads to a fundamentally new regime for optical arbitrary waveform generation(13), in which the advantages of pulse shaping and of frequency combs are exploited simultaneously. Here we demonstrate programmable line-by-line shaping of more than 100 spectral lines, which constitutes a significant step in scaling towards high waveform complexity. Optical arbitrary waveform generation promises to have an impact both in optical science ( allowing, for example, coherent control generalizations of comb-based time - frequency spectroscopies(10)) and in technology (enabling new truly coherent multiwavelength processing concepts for spread-spectrum lightwave communications and light detection and ranging, lidar).