A method for wavelength tunable output from a broadband spectrum using a quasi phase-matched optical parametric amplifier/difference frequency generator (CQPM OPA/DFG)-based apparatus involves changing the relative timing of a pump pulse with respect to a seed pulse. The temporal variation varies the location of the spatial/temporal overlap of the spectrally narrow pump pulse over the spectrally broad seed spectrum occurring within the CQPM nonlinear medium. This overlap position determines the portion of the seed pulse that is phase-matched as the signal in the OPA or the seed for DFG. Piezo-electric fiber stretchers may be employed to vary the relative pulse timing and enables tuning of the output from the OPA or DFG without the use of any moving parts. Associated apparatus is disclosed.
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