With the assistance of a focused infrared beam heating, laser-fused fiber taper optical coupler features a significantly smaller package in comparison with conventional flame fused coupler and is readily to fit in modern compact devices. A design of optical fiber microcoupler with a fused length 200μm is presented. As an effort to search for optimal low loss coupling, optical properties of the micro-coupler were studied for various taper lengths from 1000 to 6000 μm as well as for different diameters in coupling region. Beam Propagation Method (BMP) was used to simulate the operation of microcoupler and the theoretical result was compared with measured property. An optimum design for a 3dB microcoupler as example was found at a taper length of about 1320 μm and coupling diameter of 14 μm with an excellent coupling efficiency.
"A design of optical fiber microcoupler with laser-fused biconical tapers", Proc. SPIE 6025, ICO20: Optical Communication, 60251P (28 January 2006); doi: 10.1117/12.667074; https://doi.org/10.1117/12.667074