Basic Knowledge about Split Ratio and Insertion Loss of Optical Splitter

Optical splitters play a crucial role in Fiber to the Home (FTTH) Passive Optical Network (PON) systems, efficiently distributing a single optical signal to multiple destinations. The split ratio and insertion loss are two key parameters defining their performance. A deeper understanding of these fundamental concepts is essential for establishing efficient optical communication systems. In this article, you will learn the basic knowledge about split ratio and insertion loss of optical splitter.

Optical Splitter Overview

Optical splitters, encompassing FBT (Fused Biconical Taper) couplers and PLC (Planar Lightwave Circuit) splitters, are prevalent passive optical devices designed to divide fiber optic light into multiple segments based on a specified ratio. Fiber optic splitters are vital components within communication networks. Their pivotal role lies in the efficient dissemination of information to numerous recipients, allowing for simultaneous transmission without compromising signal quality or speed. You can check the article What Is an Optical Splitter? for more detailed information.

Definition of Split Ratio

The splitter ratio in fiber optic networks refers to how optical power is distributed among the output ports of an optical splitter. Expressed as a ratio or percentage, the splitter ratio indicates the division of optical power among the output ports. For instance, a 1:8 splitter ratio signifies an equal distribution of incoming optical power among eight output ports, with each port receiving 1/8th of the total power. Similarly, a 50:50 splitter ratio indicates an even split of power between two output ports. Common splitters include 1x2 fiber splitter, 1x4 fiber splitter, 1x8 fiber splitter, and 1x32 fiber splitter. The fiber splitter ratio is pivotal in determining signal strength at each output port. Careful selection of the splitter ratio is crucial to maintaining an acceptable signal strength at each destination. Improper configuration of the ratio may lead to signal degradation and loss, impacting the overall performance of the fiber optic network.

Definition of Insertion Loss

Optical insertion loss refers to the signal loss resulting from the insertion of components such as connectors or splices in an optical fiber system. Minimizing insertion loss from the optical splitter is crucial for conserving the power budget of a PON system. The table below illustrates typical losses for fiber couplers. Signal loss within a system is measured in decibels (dB), representing the degree of signal power attenuation.

Note:

1. Excess loss is the ratio of the optical power launched at the input port of the splitter to the total optical power measured from all output ports. It assures that the total output is never as high as the input.

2. Insertion loss is the ratio of the optical power launched at the given input port of the splitter to the optical power from any single output port. The insertion loss includes the splitting loss and excess loss.

How to Calculate Split Ratio and Insertion Loss?

The equation below can be used to estimate the split ratio and insertion loss for a typical split port. SR=Pi/Pt×100%

IL= -10xlog(SR/100)+Гe

where IL = splitter insertion loss for the split port, dB

Pi = optical output power for single split port, mW

Pt = total optical power output for all split ports, mW

SR = splitting ratio for the split port, %

Γe = splitter excess loss (typical range 0.1 to 2 dB), dB

Some of the common split ratios and their equivalent optical insertion loss is available below for reference.

Conclusion

In summary, understanding split ratio and insertion loss of optical splitter is vital for optimizing fiber optic networks. The split ratio dictates power distribution among ports, impacting signal strength. Minimizing insertion loss, including splitting and excess loss, ensures efficient signal transmission.