Second harmonic optimization of a hologram

摘要

Precise control of diffraction peaks of a hologram is indispensable in holographic femtosecond laser processing. To obtain the uniform diffraction peaks, an adaptive optimization due to the diffraction peaks measured by an image sensor was proposed. It used a one-photon absorption. However, the structure processed by a femtosecond laser pulse was based on multi-photon absorptions. Therefore, a mismatch between the optimized diffraction peaks and the processed structures was observed. An adaptive optimization method using second harmonics induced by parallel pulse irradiations to a nonlinear optical crystal is proposed to solve this mismatch.