Fiber optics is becoming the most commonly used mode of data transmission. They have many advantages over electrical signal transmissions, and they have a wide signal bandwidth.

As the applications of fiber optics are increasing rapidly, the problem of transmitting optical signals without losing its properties has become a common issue. However, this problem is now being solved with the invention of the fiber optic rotary joint.

These rotary joints, which are also known as fiber optic slip rings, are practical alternatives to transmitting digital or analog information along the conventional wire.

FORJ is created in the means of passing optical signals across the rotating devices and to transmit a high volume of data efficiently.

This kind of rotary joints are very efficient, cost-effective, compact, and do not lose any signal strength.

Moflon has been creating the FORJs for last 30 years and now are recognized all over the world as an industry leader.

Moflon’s MFO series fiber optic + electromagnetic slip rings allow the transmission of the optical signal from a stationary surface to a rotating surface.

In this article, we will discuss what the advantages of fiber optic rotary joints are, how do they work, what are the different types, and what are the various applications of this kind of joints.

So, Why Do We Use Fibre Optic Systems?

• These are thinner than copper wires.

• Fiber optic system has a High Signal Carrying Capacity as they are thinner and more fiber cables can be bundled in a given diameter.

• They have less signal degradation than conventional slip rings.

• They have unlimited bandwidth capacity and thus a perfect option for carrying digital signals.

• As signals in these cables degrade less, it requires lesser power to transmit a high volume of data.

Advantages of Fibre Optic Rotary Joints

• They are capable of offering wide signal bandwidths which allow carrying a high amount of information. For example, the FORJs by Moflon are capable of transmitting up to 100 Gbps.

• Mostly, FORJs are bidirectional, and it is capable of transferring optical signals along with the rotational interfaces.

• These have very low or no noise.

• These are cost effective and provide a come with a long life-span.

• Are capable of withstanding harsh environments.

• Comes with compact sizes.

• Customized options available according to uses need.

How Does a Fibre Optic Rotary Joint Work?

The primary function of FORJs is to provide connections between single and multi-channel fiber cables allowing a free rotation between the cables.

Some FORJs use a precise lens and prisms to align and funnel the light and the data that the light is carrying. It can carry the data over an air gap while the component is rotating.

What Are the Different Types of FORJs?

By function, the fiber optic rotary joint can be classified into two types, active and passive.

An active FORJ unit has a light source at one end and the detector and the rotary surface on the other hand.

These rotary joints are also available in single and multi-channel options.


For a situation where optical signals need to be transmitted along a single fiber, a single-channel optical rotary joint can be used.

A single fiber enters either side of the rotating interface, and then optical signals are coupled between them while one fiber rotates relative to the other one.

It works by enlarging the diameter of the coupled light by using the lens, large diameter fiber, or fiber bundles.

They also come in single-mode or multi-mode functionality.

First, let us discuss the multi-channel rotary joint. We will discuss the single-mode and multi-mode at a later stage.


For any situation where optical signals need to be transmitted across different fibers or fiber bundles, a multi-channel FORJ is necessary.

From a mechanical perspective, a multi-channel FORJ is much more complicated than a single-channel FORJ. These are also physically bigger than the single-channel FORJs.

Multi-channel optical rotary joints are available in different configuration.

Here at Moflon, we have 2, 4, 6, and 8 channel optical rotary joints, single or multimode.

For example, our 4-channel fiber optic slip ring MFO400A supports 4 channel fiber optics. It is efficient in transmitting a large volume of data from a permanent position to a rotation position (unlimited, continuous, or discontinuous) which improves the mechanical property and simplifies the operation.

Single-Mode or Multi-Mode

Single-mode fibers allow the propagation of a single mode of optical energy as they have a smaller core size and numerical aperture. Due to this fact, these have a very high, and thus the single mode optical rotary joints need very precious mechanical alignments.

Single-mode FORJs operate at a wavelength between 1271 nm and 1611 nm.

On the other hand, multimode fibers have a bigger core size and numerical aperture and are capable of propagating multiple modes of optical energy.

Multi-mode FORJs operate at a wavelength between 850 nm to 1300 nm.

The Applications of Fibre Optic Rotary Joints

Fiber optic rotary slip rings have a wide range of applications. These are used on any devices that are designed to transmit audio and other various signals when 360-degree rotating.

Some of the typical applications of FORJs are:

• Radars

• Medical systems

• Robotics

• UAVs

• Fiber optics

• ROVs

• Laser cutters (rotating)

• Ultra HD video transmitting

• Intelligence toys

• Marine propulsion activities

• Security mechanisms

• Video surveillance


By now, we have a clear idea of how fiber optic rotary joint works. We have seen that this optical rotary joint has minimized the signal loss on fiber optic devices and also provides a seamless connection between a stationary and rotating surface.

The efficient mechanism and wide range of functionalities make this fiber optic rotary joint an essential part of any optical devices.

You can have single-channel, or multi-channel FORJs according to your application. You can also get customized fiber optic rotary slip ring solutions.

Please comment below to let us know what do you think about the FORJ and also, do not hesitate to ask us any question if you need to know more about this component.