NIR photopolymerization self-writing process for fiber-to fiber and VCSEL-to-fiber single mode coupling
Résumé
Low-loss coupling of VCSELs (vertical-cavity surface-emitting lasers) to optical fibres is a key issue for increasing their
use in optical communications and instrumentation systems. However, tolerances on angular tilts and lateral misalignments are tight, particularly in the case of single mode devices. To address this challenge, a new fabrication method based on near-infrared single-mode self-writing (NIR-SM-SWW) of a polymer waveguide was developed and tested for the coupling of two single mode fibers at 850 nm (Thorlabs 780-HP) with a mode field diameter close to that of 850 nm single mode VCSEL. The specificity of our method is to use a writing wavelength identical to that designed for single mode propagation in the fibers, leading to a single step photopolymerization process that will be directly transferable to 850 nm VCSEL-to-fiber coupling. First results show coupling losses at 850 nm as low as 0.86 dB for a distance between the fibers of 100 μm.