Direct Carrier-Envelope Phase Control for Coherent Synthesis with a Dual-Color Femtosecond Optical Parametric Oscillator

Coherent synthesis offers a route to sub-femtosecond laser pulses but generally requires a spectral bandwidth wider than the emission from a single laser. A direct way to realize this is to combine outputs from several independent lasers coherently by controlling their relative phases and pulse repetition frequencies. Using outputs from a synchronously pumped ultrafast optical parametric oscillator for coherent synthesis passively ensures that the pulses have perfectly matched repetition frequencies, relaxing the technical constraints on achieving coherent synthesis.