Femtosecond Laser‐Induced Refractive Index Patterning in Inorganic/Organic Hybrid Films

Abstract

The desire to increase the performance of optoelectronic devices has driven research into new, versatile optical materials. Among these, materials combinations composed of organic polymers and inorganic materials have sparked a strong interest due to the wide range of refractive indices that are obtainable. However, in parallel to these materials design and discovery activities, simple, broadly applicable fabrication techniques need to be advanced that are adapted to novel materials systems and allow, for instance, straightforward, large‐area manufacturing and integration of 3D photonic circuits. Herein, the use of a 3D direct writing laser technique is proposed to locally enhance the refractive index of a recently developed inorganic/organic molecular hybrid that is only composed of the commodity polymer poly(vinyl alcohol) cross‐linked with titanium oxide hydrates, for the creation of photonic structures. A spatially controlled refractive index increase of 0.13 between pristine and laser‐treated regions is achieved, with the potential of this adaptable 3D‐fabrication technique being demonstrated by manufacturing an optical diffraction grating. Considering that the synthesis and deposition of the hybrid material is water based and does not require toxic heavy metals, the work, thus, provides a processing and materials platform toward environment‐friendly, green processing of integrated photonic systems and beyond.