Comparison of FBT and PLC Fiber Optic Splitters

The past few years have witnessed a great leap in advancements of fiber optic communication technologies, these progresses are made to cater to the ever accelerating demand for better and more efficient optical performances. Fiber optic splitter, which plays a significant role in optical networks by allowing signals on an optical fiber to be shared among two or more fibers. Basically, there are two types of fiber optic splitters: fused biconical taper splitter (FBT) and planar lightwave circuit splitter (PLC). And each of them obtains some merits and demerits respectively. This article intends to make a comparison of these two thus to provide some useful information about optical splitters.

Introduction to Fiber Optic Splitter

Fiber optic splitter, known as beam splitter as well, is suitable for a fiber optic signal to be decomposed into multi-channel optical signal output. It divides out a main light source into 1-N optical path and synthesizes 1-N optical path into a main light source and recovers this source. The picture below shows how light in a single input fiber can split between four individual fibers.

Basically, there are two types of optical splitters classified by their working principle: one is fused biconical taper splitter (FBT Splitter) made by the traditional optical passive device manufacturers using the traditional biconical taper coupler technology. The other one is planar optical waveguide splitter (PLC Splitter) based on optical integration technology. Since both of them have their own advantages, users can rationally choose different types of optical splitters depending on the occasion and demand. Besides, it is better to follow a brief introduction of these two devices just for reference.

FBT Splitter

FBT is the traditional technology in which two fibers are placed closely together, typically twisted around each other and fused together by applying heat. The fused fibers are protected by a glass substrate and then protected by a stainless steel tube. The quality of FBT splitters has improved over time and they can be deployed in a cost-effective manner. FBT splitters are widely accepted and used in passive optical networks, especially for where the split configuration is no more than 1×4.

However, when larger split configurations such as 1×16, 1×32 and 1×64 are needed. FBT technology is limited to the number of splits that can be achieved with one coupling. Under such circumstance, multiple FBT splitters can be spliced together in concatenation to multiply the amount of splits available. This is also known as a tree splitter or coupler. When using this design, the package size and the insertion loss increases with the additional splitters and splices used.

PLC Splitter

PLC splitters are used to separate or combine optical signals. A PLC is a micro-optical component based on planar lightwave circuit technology and provides a low cost light distribution solution with small form factor and high reliability. PLC splitters have high quality performance, such as low insertion loss, low PDL, high return loss and excellent uniformity over a wide wavelength range from 1260 nm to 1620 nm and have an operating temperature -40℃ to 85℃. When high split counts are needed and small package size and low insertion loss is critical, a PLC splitter is more ideal.

Differences Between FBT Splitter and PLC Splitter

In this part, we will take a look at the main differences between FBT splitter and PLC splitter from eight perspectives, which are listed in the following diagram.

Parameters	FBT Splitter	PLC Splitter
Fabrication Method	Two or more pieces of optical fibers are bound together and put on a fused-taper fiber device. The fibers are then drawn out according to the output branch and ratio with one fiber being singled out as the input.	Consists of one optical chip and several optical arrays depending on the output ratio. The optical arrays are coupled on both ends of the chip.
Operating Wavelength	1310 nm and ISSO nm (standard), 850 nm (custom)	1260 nm-1650 nm (full wavelength)
Application	HFC (network of fiber and coaxial for CATV), All FTIH applications.	Same
Performance	Up to 1:8—reliable. For larger splits reliability can become an issue.	Good for all splits. High level of reliability and stability.
Input/Output	One or two inputs with an output maximum of 32 fibers.	One or two inputs with an output maximun of 64 fibers.
Package	Steel Tube (used mainly in equipment), ABS Black Module (Conventional)	Same
Input/Output Cable	Bare optical fiber, 0.9 mm, 2.0 mm, and 3.0 mm	Same
Part Number Example	FOSPLT-T-FBT-1/2-E-SM-SC/APC	FOSPLT-T-PLC-1/2-E-SM-SC/APC

Conclusion

Although the outer appearance and size of FBT and PLC splitters seem rather similar, their internal technologies and specifications differ in various ways. I hope the comparison made by this article would help you have a better understanding of these two types of optical splitters, so you could choose a more appropriate solution for your network infrastructure.

First published: http://www.fiber-optic-solutions.com/comparison-fbt-plc-fiber-optic-splitters.html

Coupler and Splitter Overview

It is generally accepted that fiber, connectors and splices rank are the most important passive devices. However, what closely following are tap ports, switches, wavelength-division multiplexers, bandwidth couplers and splitters. These devices divide, route or combine multiple optical signals. Splitter is named by the function of the device while coupler is named by its working principle.

Definition of Couplers

Fiber optic couplers either split optical signals into multiple paths or combine multiple signals on one path. Optical signals are more complex than electrical signals, making optical couplers trickier to design than their electrical counterparts. Like electrical currents, a flow of signal carriers, in this case photons, comprise the optical signal. However, an optical signal does not flow through the receiver to the ground. Rather, at the receiver, a detector absorbs the signal flow. Multiple receivers, connected in a series, would receive no signal past the first receiver which would absorb the entire signal. Thus, multiple parallel optical output ports must divide the signal between the ports, reducing its magnitude. The number of input and output ports, expressed as an N x M configuration, characterizes a coupler. The letter N represents the number of input fibers, and M represents the number of output fibers. Fused couplers can be made in any configuration, but they commonly use multiples of two (2 x 2, 4 x 4, 8 x 8, etc.). The following picture shows a typically optical coupler.

Definition of Splitters

Fiber optic splitter is a device that splits the fiber optic light into several parts by a certain ratio. The simplest couplers are fiber optic splitters. These devices possess at least three ports but may have more than 32 for more complex devices. Fiber optic splitters are important passive components used in FTTx networks. Two kinds of fiber splitters are most used: one is the traditional fused type fiber optic splitter FBT splitter, which features competitive prices. And the other is PLC fiber optic splitter, which is of compact size and suit for density applications.

Just like fiber patch cable, fiber splitters are usually with 0.9mm, 2mm or 3mm cables. 0.9mm outer diameter cable is mostly used in stainless steel tube package fiber optic splitters, while 2mm and 3mm cables are mostly used in box type package fiber splitters. Based on working wavelength difference there are single window and dual window fiber optic splitters. And there are single mode fiber splitter and multimode fiber splitter. The picture below shows an optical splitter.

Coupler and Splitter Applications

Optical coupler is generally used in applications that require links other than point-to-point links, which includes bidirectional links and local area network. (LAN). Moreover, it serves as an important components used in WDM systems to route and split signals, monitor the network, or combine signal and pump wavelengths for feeding optical amplifiers.

Fiber optic splitter can be used for FTTx/PON application. This helps to reduce the physical fiber usage or the basic quantity of required fibers. A single fiber can be split into many branches to support multiple end users. The strain on the fiber backbone can be greatly decreased through the application. In addition, fiber optic splitter can also be employed in the maintenance of long-haul network, cable TV ATM circuit or local area/metro area network.

Conclusion

To sum up, fiber optic couplers or splitters are available in a selection of styles and sizes to separate or combine light with minimal loss. This article has presented you some basic knowledge related to couplers and splitters and may help you select the right one that most satisfies your need.

First published: http://www.fiber-optic-solutions.com/coupler-splitter-overview.html