Optical couplers and splitters pdf

A fiber optic coupler is a device that can distribute the optical signal from one fiber among two or more fibers, or combine the optical signal from two or more fibers into a single fiber. Usually, optical signals are attenuated more in an optical coupler than in a connector or a splice because the input signal is not directly transmitted from one fiber to another, but divided among the output ports. For instance, with a 1 x 2 fiber optic coupler, each output is less than one-half of the power of the input signal over a 3dB loss.

A basic fiber optic coupler has N input ports and M output ports. N and M typically range from 1 to The number of input ports and output ports varies depending on the intended application for the coupler. Under different principles, fiber optic couplers can be categorized differently. The different types of optical couplers will be explored in the following part.

Technologies used for constructing optical couplers can be complex and difficult to understand. Three major manufacturing techniques are micro-optics, fused-fiber, and planar waveguide. Micro-optics couplers use individual optical elements such as prisms, lens, mirrors, etc.

These elements divide the input optical signal into two or more separated light beams. Fused-fiber couplers used the most basic material—optical fiber. Two or more fiber cores are twisted, fused and tapered together in a length. Planar waveguides are more like a semiconductor.

A planar wafer is used to make a waveguide coupler, and the reflections occur only in y-directions. Planar waveguides are more often used to make high port count couplers, such as 1 x 12 PLC splitter, 1 x 24 PLC splitter. If we see optical couplers by shape, there is Y coupler, T coupler, X coupler, star coupler and tree coupler, which split the optical signal based on the power. A Y coupler resembles the letter Y. Y coupler also called optical tap coupler.

The input signal is split into two output fibers. Sometimes, to meet users' specific applications, the power distribution ratio also can be controlled precisely. Unlike the Y coupler, a T coupler has an uneven power distribution. The power of one output signal is greater than the other output signal. Popular splitting ratios include percent and percent. This optical coupler is often used in small networks with less port counts.

X Coupler 2x2. X couplers carry out the function of a splitter and a combiner in one package. The X coupler combines and divides the optical power from the two input fibers between the two output fibers. Another name for the X coupler is 2 x 2 coupler. A star coupler generally has several input and output port combinations, in which the optical power is distributed from more than two input ports among several output ports.

It is generally accepted that fiber, connectors, and splices rank is the most important passive devices. However, what closely following are tap ports, switches, wavelength-division multiplexers, bandwidth coupler, and splitter. 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.

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 typical optical coupler.

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.