Channel guide behavior of optical beams upon initiating photopolymerization

Waveguides can be self-written in photosensitive or photopolymerizable materials. This process results from the competition of the diffraction of the incident Gaussian beam and photopolymerization which tends to increase the refractive index where the light intensity is the highest. We have investigated the condition of quasi-solitonic and chaotic waveguide propagation inside bulk photopolymerizable materials. Light has been introduced in the medium by a single mode optical fiber. The propagated light behavior can be controlled by a careful monitoring of the input intensity. Indeed, a unique uniform channel wave guide without any broadening has been obtained by polymerization using a very low beam power of 5 μW. By increasing the input power up to 100 μW, the guide becomes chaotic and multi-channel, a process which has not been studied before in these materials. Although the transmission efficiency of two fibers connected by this type of guide is weak (10%), we can nevertheless couple two guides separated by a distance of a few millimeters. Now, this allows the study of the optical and electro-optical properties of photopolymerized guides doped by nonlinear optical chromophores and possible applications in integrated optical devices.