What Is an Optical Splitter?

Unraveling the Power of Optical Splitters in Modern Networks

In today's optical network topologies, the advent of fiber optic splitters contributes to maximizing the performance of optical network circuits. Also known as optical splitters, fiber splitters, or beam splitters, these integrated waveguide optical power distribution devices play a pivotal role in passive optical networks like EPON, GPON, BPON, FTTX, FTTH, etc., by allowing a single PON interface to be shared among multiple subscribers.

What Is Optical Splitter?

Fiber optic splitters, also referred to as optical splitters, fiber splitters, or beam splitters, are integrated waveguide optical power distribution devices that split an incident light beam into two or more light beams, and vice versa. They consist of multiple input and output ends and have become indispensable in passive optical networks, enabling a single PON interface to serve numerous subscribers.

How Does Optical Splitter Work?

When light signals transmit in single-mode fibers, the light energy cannot be entirely concentrated in the fiber core. A small amount of energy will be spread through the fiber cladding, allowing transmitting light to enter another optical fiber if they are close enough. This principle enables the reallocation technique of optical signals in multiple fibers, giving rise to the development of fiber splitters.

Fiber Optic Splitter Working Principle

Specifically speaking, a passive optical splitter can split, or separate, an incident light beam into several light beams at a certain ratio. Let's consider the basic 1x4 split configuration: It separates an incident light beam from a single input fiber cable into four light beams, transmitting them through four individual output fiber cables. For instance, if the input fiber optic cable carries a 1000Mbps bandwidth, each user at the end of the output fiber cables can use the network with a 250Mbps bandwidth.

The optical splitter with 2x64 split configurations is a little more complicated than the 1x4 split configuration. It has two input terminals and sixty-four output terminals. The 2x64 splitter splits two incident light beams from two individual input fiber cables into sixty-four light beams, transmitting them through sixty-four individual output fiber cables. With the rapid growth of FTTx worldwide, the requirement for larger split configurations in networks has increased to serve a greater number of subscribers.

Optical Splitter Types

Optical splitters are classified based on their package style, transmission medium, and manufacturing technique.

Classified by Package Style

The optical splitter can be terminated with different forms of connectors, and the primary package could be a box type or stainless tube type. Fiber splitter box is usually used with 2mm or 3mm outer diameter cables, while the other is normally used in combination with 0.9mm outer diameter cables. Various split configurations are available, such as 1x2, 1x8, 2x32, 2x64, etc.

Classified by Transmission Medium

Based on the different transmission mediums, there are single-mode optical splitters and multimode optical splitters. Multimode optical splitters are optimized for 850nm and 1310nm operation, whereas single-mode optical splitters are optimized for 1310nm and 1550nm operation. Additionally, based on working wavelength differences, there are single window and dual window optical splitters. The former uses one working wavelength, while the latter is equipped with two working wavelengths.

Classified by Manufacturing Technique

There are two main types of optical splitters based on manufacturing techniques: Fused Biconic Taper (FBT) splitter and Planar Lightwave Circuit (PLC) splitter.

FBT splitter: Based on traditional technology, FBT splitters weld several fibers together from the side of the fiber, resulting in lower costs.

PLC splitter: Based on planar lightwave circuit technology, PLC splitters are available in a variety of split ratios, including 1:4, 1:8, 1:16, 1:32, 1:64, etc. They come in several types, such as bare PLC splitter, blockless PLC splitter, ABS splitter, LGX box splitter, fanout PLC splitter, and mini plug-in type PLC splitter.

How to Choose the Right Fiber Splitter?

A superior fiber optic splitter needs to pass a series of rigorous tests, and several performance indicators affect its efficiency.

• Insertion loss: Refers to the dB of each output relative to the input optical loss. The smaller the insertion loss value, the better the splitter's performance.

• Return loss: Also known as reflection loss, refers to the power loss of an optical signal that is returned or reflected due to discontinuities in the fiber or transmission line. A larger return loss is desirable.

• Splitting ratio: Defined as the output power of the splitter output port in the system application, it is related to the wavelength of the transmitted light.

• Isolation: Indicates a light path optical splitter's ability to isolate optical signals from other optical paths.

Uniformity, directivity, and polarization-dependent loss (PDL) are other crucial parameters affecting the performance of the splitter.

For specific selections, FBT and PLC are the two main choices for most users. The differences between FBT splitter vs. PLC splitter usually lie in operating wavelength, splitting ratio, asymmetric attenuation per branch, failure rate, etc. FBT splitters are cost-effective solutions, while PLC splitters offer good flexibility, high stability, low failure rate, and wider temperature ranges for high-density applications.

Concluding Remarks

Optical splitters play a critical role in modern fiber-optic networks by enabling efficient signal distribution. As they contain no electronics and do not require power, they are integral components in most fiber-optic networks. Choosing the right fiber optic splitter is essential for developing a network architecture that can withstand the demands of the future.