Inkjet printing of high‐refractive‐index optical waveguides designed for single‐mode operation is presented. A waveguide core is printed with titanium dioxide nanoparticles that form a straight strip with a high refractive index. The quartz glass without preliminary processing is used as a substrate. The optimal waveguide thickness to provide single‐mode operation in the near‐IR range is calculated. The number of printed layers necessary to obtain the required thickness and the refractive index is established. The printing parameters to provide suitable morphology for waveguide application are thoroughly studied. Measurements confirm light propagation through the printed waveguides at 1.55 µm wavelength, and the mean power loss is estimated as 3.52 dB cm−1. The branched structure is printed, and its ability to transmit and split light is demonstrated. The received data have a directly applied value for application in the future development of integrated optical circuits and printing technologies.

The tendency to develop flexible and transparent materials has been growing in the last decade. As inkjet printing technology has become a widespread method for the fabrication of functional materials, the investigation of the inkjet printing process seems to be essential with regard to polymers, which are a viscous and flexible media. In this study, we evaluated the dependence of ink drop coalescence on process parameters such as polymer viscosity (controlled by polymerization time), drop spacing and drop speed. The results showed that drop coalescence was mostly influenced by drop speed, while drop spacing and substrate polymer viscosity did not significantly affect the printing results. The presented data are crucial for understanding the processes involved in the fabrication of flexible materials by inkjet printing.