Dynamic ultrafast laser beam tailoring for multispotphoto-inscription of photonic devices in bulk transparentmaterials

摘要

Femtosecond laser processing of bulk transparent materials can generate localized increase of the refractiveindex. Thus, translation of the laser spot give potential access to three dimensionnal photowriting of waveguidingstructures. Increasing the number of machining foci can considerably reduce the processing efforts when complexphotonic structures are envisaged such as waveguide arrays. The present report presents a technique of dynamicultrafast laser beam spatial tailoring for parallel writing of photonic devices. The wavefront of the beam ismodulated by a periodical binary (0-π) phase mask of variable pattern to achieve dynamic multispot operation.The parallel photoinscription of multiple waveguides is demonstrated in fused silica. Using this method, lightdividers in three dimensions relying on evanescent coupling are reported and wavelength-division demultiplexing(WDD) devices were achieved in single sample scan.