The input port of an optical splitter generally has the lowest loss compared to individual output ports.

Understanding Insertion Loss

Insertion loss measures the reduction in optical power as a signal passes through a splitter. It includes both splitting loss (due to dividing the signal among multiple outputs) and excess loss (from imperfections in the splitter) . The input interface itself does not experience splitting, so the optical power entering the splitter is minimally attenuated at this point, making it the interface with the lowest loss.

Output Port Loss

Each output port experiences additional loss proportional to the split ratio. For example, a 1×2 splitter divides the input power roughly in half, resulting in an insertion loss of about 3.5 dB per output port, while a 1×8 splitter can have insertion losses around 10.5 dB per output port . Higher split ratios increase the loss at each output port because the input power is distributed among more channels .

Factors Affecting Loss

• Splitter type: PLC (Planar Lightwave Circuit) splitters typically have lower excess loss than FBT (Fused Biconical Taper) splitters, with modern PLC splitters achieving insertion losses as low as 0.3 dB for small split ratios .
• Wavelength: Loss can vary slightly depending on the operating wavelength (e.g., 1310 nm, 1490 nm, 1550 nm).
• Quality and manufacturing: High-quality components reduce excess loss, improving overall performance.

Practical Implication

For network design, minimizing loss is crucial to maintain sufficient optical power at the receivers. While the input port inherently has the lowest loss, careful selection of splitter type, split ratio, and quality ensures that output ports also maintain acceptable signal levels for reliable operation . In summary, the input interface of an optical splitter has the lowest loss, while each output port experiences additional insertion loss depending on the split ratio and splitter type.