A method for operating a wavelength-converted light source includes directing a pump beam having a fundamental wavelength from the laser source into an input facet of the wavelength conversion device such that a wavelength-converted output beam is emitted from an output facet of the wavelength conversion device in the field of view of an optical detector. A physical property of the wavelength conversion device is varied within individual ones of a succession of consecutive speckle reduction intervals having durations less than the integration time of the optical detector. The physical property of the wavelength conversion device is varied by an amount that is sufficient to change in a phase-matched (PM) wavelength of the wavelength conversion device. The fundamental wavelength of the pump beam is thereafter adjusted based on the change in the PM wavelength to maintain an efficiency of the wavelength conversion in the wavelength conversion device.