What Is an Optical Attenuator?

An optical attenuator decreases the strength of an optical signal passing through it to a fiber optic cable or open air. The intensity of the signal is described in decibels over a specific distance the signal travels. It is the strength, or amplitude of the signal that changes and not the overall waveform or frequency, so the optical signal remains undistorted for use in the desired application. Optical attenuators are often used in optical communication systems, in which the attenuation, also called transmission loss, helps with the long-distance transmission of digital signals. The most common optical attenuator types include fixed and continuously variable attenuators.

Often installed where signals are transmitted from, an optical attenuator can apply the principle of gap loss so the signal intensity is lowered to the optimal level over a given distance. Attenuators installed elsewhere along the optical fiber will not lower the signal strength enough, but some devices utilize signal absorbing or reflecting components to compensate. An optical fiber connector is often attached to the optical attenuator which typically has an adapter with a female configuration. The attenuator itself usually has a cylindrical or even box-like structural shape which determines the type of equipment in which it can be installed.

The fixed variety of optical attenuator, sometimes found in an electronic circuit, does not reflect light signals to reduce their intensity. It is generally used where the transmission of data needs to be highly accurate. The device’s function is determined by the amount of power it can handle in addition to important variables such as performance versus temperature and frequency range. Most optical attenuators utilize resistors, but a variable optical attenuator uses metal semiconductor field effect transistors or other solid state components. Attenuation intensity is adjustable so the signals in a fiber optic communication system can be changed to accommodate fluctuating power levels, protecting the system from damage.

A variable optical attenuator can be mounted on a printed circuit board, or used in test devices such as an optical power meter. Many attenuators are installed in-line with an optical fiber cable in order to adjust the transmitted signal accordingly. They are sold by many retailers and manufacturers online so one can assess their characteristics by reading the product specifications. Aspects to consider include the average and peak power the device can tolerate, how much attenuation it provides, as well as its overall dimensions and the type of environment it can operate in.

How Much Do You Know About PLC Splitter?

What Is PLC Splitter?

PLC splitter, also called Planar Waveguide Circuit splitter, is a device used to divide one or two light beams to multiple light beams uniformly or combine multiple light beams to one or two light beams. It is a passive optical device with many input and output terminals, especially applicable to PON (EPON, GPON, BPON, FTTX, etc.) to connect the MDF (main distribution frame) and the terminal equipment and to branch the optical signal.

PLC splitter provides a low-cost light distribution solution with high stability and reliability. PLC splitters can offer a splitting ratio of up to 1×64, which is generally higher than the splits of FBT splitter that another common type of optical splitter.

PLC Splitter Manufacturing Technology

PLC splitter is based on Semiconductor technology. As its name shows, PLC splitters are manufactured by planar waveguide circuit technology. PLC splitter design consists of one optical PLC chip and several optical arrays depending on the output ratio. The optical arrays are coupled on both ends of the PLC splitter chip.

PLC chip is one key component of a fiber PLC splitter. It is available in 1xN (N=2, 4, 8, 16, 32, 64) and 2xN (N=2, 4, 8, 16, 32, 64) splitting ratios. The figure below shows the typical design of a 1×8 PLC splitter chip.

Different Types of PLC Splitters

There are PLC splitter types in the market. Fiber optic PLC splitter can be categorized by the PLC splitter chip they use, meaning there are 1xN and 2xN PLC splitters, such as 1×4 splitter, 1×8 splitter, 1×16 splitter, 2×32 splitter, 2×64 PLC splitters, etc. Users can choose different input and output numbers depending on subscriber conditions or cable length.

In addition, PLC splitters also can be classified based on different packages to meet clients’ needs in various scenarios, including small size PLC splitter that needs to be used in terminal boxes and big size rack mounted PLC that can be installed in racks. All the following PLC splitters with different packages also support 1×2/4/8/32 forms. The different split ratio will cause different loss levels in PLC splitters. The following table shows the common different types of PLC splitters.

How Does PLC Splitter Work?

In passive optical networks (PON), PLC splitter is widely installed between the PON Optical Line Terminal (OLT) and the Optical Network Terminals/Units (ONTs/ONUs) that the OLT serves. The single fiber link coming from the Central Office (CO) OLT is connected with the input of a splitter and is split into a given number of fibers leaving the splitter. The number of outputs in the PLC module determines the number of splits.

PLC splitters can be used in centralized PON architecture or distributed architecture. In a centralized PON architecture, a 1×32 PLC splitter is often used in the Central Office. In a distributed PON architecture, a 1×4 PLC splitter is firstly directly connected to an OLT port in the Central Office, then each of the four fibers is routed to an outside plant terminal/enclosure box that houses a 1×8/1×4 PLC splitter.


As demand for higher bandwidth continues to grow, telecommunications companies rely on the PON network and need reliable PLC splitters to provide fiber optic links to an increasing number of users. PLC splitters allow a single PON network interface to be utilized by multiple users, maximizing a fiber network’s user capacity, offering the best solution for network builders.

Author: Fiber-MART.COM

eShop of Fiber Optic Network, Fiber Cables & Tools

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