How to fuse a 1 2 optical splitter

A 1-to-2 optical splitter is made by fusing and tapering two fibers together so that the input signal is evenly divided between two output fibers.

Overview of Fused Fiber Splitters

A fused fiber splitter, also called a fused biconical taper (FBT) splitter, works by heating two optical fibers until they fuse and taper, creating a coupling region where light from the input fiber is distributed between the two output fibers. This method is suitable for both singlemode and multimode fibers, though singlemode fibers are highly wavelength-dependent while multimode fibers are mode-dependent .

Step-by-Step Fusion Process

1. Prepare the Fibers: Strip the protective coating from the fibers to expose the bare glass. Clean the fibers thoroughly to remove dust and oils.
2. Align the Fibers: Place the two fibers parallel to each other in a fusion jig or holder. Ensure the cores are closely aligned to maximize coupling efficiency .
3. Heat the Fibers: Use a fiber fusion splicer or a controlled flame to heat the fibers until the glass softens. The fibers will begin to fuse together at the contact point .
4. Taper the Coupling Region: While heating, gently pull the fibers to create a tapered region. The taper length and diameter determine the splitting ratio and insertion loss. For a 1-to-2 splitter, the taper is adjusted to achieve approximately equal power distribution between the two outputs .
5. Cool and Stabilize: Allow the fused region to cool naturally. Avoid mechanical stress during cooling to prevent micro-cracks or misalignment.
6. Test the Splitter: Use an optical power meter to measure the output at both fibers. Adjust the tapering process if necessary to achieve the desired splitting ratio and minimize insertion loss .

Key Considerations

• Insertion Loss: Typical losses range from 0.2 dB to 3 dB depending on fiber type and fusion quality .
• Mode Distribution: For multimode fibers, ensure an equilibrium mode distribution using an incoherent source or a mode scrambler to maintain consistent splitting ratios .
• Wavelength Sensitivity: Singlemode fused splitters are sensitive to wavelength changes; specify the operating wavelength to maintain performance .
• Polarization Effects: Fused splitters made from polarization-maintaining fibers may not preserve polarization well at the fusion point, making them sensitive to temperature or vibration . By carefully following these steps and considerations, a 1-to-2 optical splitter can be successfully fused to provide reliable signal distribution for fiber optic networks.