Polymer Photonic Crystal Waveguides Generated by Femtosecond Laser

Abstract

Femtosecond laser‐based fabrication of integrated photonic crystal waveguides inside of a transparent polymer is reported. In general, the fabrication of waveguides based on femtosecond laser‐induced positive refractive index modifications is feasible. However, in transparent polymers their performance is limited since only minor refractive index changes can be achieved with this technique. These restrictions can be circumvented by generating hexagonal “photonic lattice like” waveguides, which consist of negative refractive index modifications in the cladding, enabling light confinement in the unirradiated core. A comprehensive study on the fabrication of this new class of polymer waveguide is performed as well as a characterization of its numerical aperture, mode field diameter, and attenuation. In addition, integration of Bragg gratings based on positive and negative refractive index modulations within the waveguide's core is studied. Moreover, we highlight that polymer photonic crystal waveguides are compatible with common femtosecond laser‐based internal structuring processes, enabling the creation of monolithic optofluidic devices, which is demonstrated by the fabrication of a Fabry–Pérot interferometer.

Current and Future Trends for Polymer Micro/Nanoprocessing in Industrial Applications

“…Overall, LBM exhibits several advantages such as a simple operational environment (there is no requirement for vacuum conditions or clean room facilities), material applicability (polymers, glass, composites, metals, and semiconductors), and diverse structures. [124,125] Moreover, because this approach does not involve any toxic chemical components, LBM is a promising approach for shape-forming and modification of biodegradable polymers. [126,127] Hybrid LBM methods, one of the future development directions, can help precisely control the microstructuring of materials ranging from fluorescent polymeric structures to superhydrophobic surfaces, composite resins, and shapememory polymers, thus promoting novel applications such as micro-supercapacitors, solar cell devices, integrated photonics, anticounterfeiting devices, and optical encryption devices.…”

Gelatin Used as a Transductor in an Optical Hygrometer Based on a Fabry-Perot Interferometer

“…It is not exactly the same, however, and the resemblance holds only when the refectance is small. Ten, the frst two refected beams are so much stronger than the rest that have little efect [10,13]. As the refectance of the surfaces is increased, the fringes due to multiple refections become narrower.…”

“…Switching powers of about 7 mW have been found. In other work [13], Bragg gratings (BGs) have been incorporated in polymer photonic crystal waveguides (PPCWs) which have been generated by femtosecond lasers. Te structure of the waveguide is inspired by the solid core photonic crystal fbers.…”

Photonic lattice-like waveguides in glass directly written by femtosecond laser for on-chip mode conversion

“…Guiding is supported by total internal reflection, which is achieved by an effective refractive index difference between a central photonic lattice-like core region and the surrounding pristine glass, and does not rely on the photonic bandgap effect. Interestingly, the PLLW is based on a sub-micro-sized densified track arrays imposing a positive refractive index change of the waveguide's core, which is completely distinct from the cases in the past [13][14][15][16][17][18][19] . By well distributing the densified tracks at sub-micron resolution, the PLLW is supposed to generate arbitrary guiding modes, including mode conversion in a single waveguide with high conversion efficiency.…”