Optical fiber is a technology that transmits digital information as light pulses through optically pure glass or plastic fibers only slightly thicker than a strand of human hair. An infrared laser or LED diode typically generates these light pulses, which can carry large amounts of data over great distances with minimal attenuation (signal loss). 

In professional video workflows, fiber is used to transport a broad range of video formats, standards, and protocols, including SDI, HDMI, SMPTE 2110, and NDI, over longer distances than traditional copper cabling supports. Depending on the application and budget, fiber-based systems can be built with cabling that contains a single fiber or multiple fibers housed inside insulated casings.  

While the size, type, and number of fibers in a cable can vary, every cable includes three key components: the core, a thin glass fiber or plastic pathway for the transmission of light pulses; cladding, which surrounds the fibers and reflects the light back into the core; and a buffer to protect the core and cladding from damage and moisture. A “strength member” like aramid yarn (Kevlar), fiberglass-reinforced plastic, or other non-metallic strength materials, and a cable jacket may also be part of the cable.  
  
Fiber optic transmission relies on total internal reflection (TIR), where light signals travel through the fiber cable’s core by bouncing off the cladding walls in a zigzag pattern. 

Now that you've had a closer look at the interior of a fiber optic cable, let’s examine the two types of fiber: single-mode and multi-mode. Understanding the differences between the two can help you determine the best choice for your facility or production. 
  
Single-mode fiber systems provide the highest transmission rates over greater distances (up to 10 km @10GbE). They offer higher signal integrity, the ability to support higher bandwidth, and minimal signal dispersion, making them ideal for long-distance and high-bandwidth communication, inter-facility network connections, broadcast networks, WAN video links, and professional video transmission over long distances. With single-mode fiber, only one mode (path) of light can propagate down the core because the very small core diameter (~9 microns) allows minimal reflections. Single-mode fiber uses laser light sources.  

These two modes are incompatible with each other and cannot be mixed between two endpoints, but both offer unique benefits. The distance you need your signal to traverse, bandwidth requirements, and budget will ultimately inform which path you take. Single-mode fiber systems can transmit signals up to 50 times further but are often more expensive than multi-mode.

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Compared to traditional copper cables, fiber cables offer several advantages for modern video infrastructure. Let’s take a closer look at each:

While we’ve already covered fiber cabling and connectors at length, there are other pieces to consider, such as SFP modules. An acronym for Small Form-factor Pluggable, SFPs are interchangeable transceiver modules. The benefit of using SFPs compared to a fixed fiber or copper interface is that individual SFP ports can be equipped with different types of transceivers as required.  

SFPs can be hot-swappable, meaning that they can be inserted or removed from a device without powering down the system and disrupting network operations. For that reason, SFP modules permit cable connectors or optical transmission wavelengths to be changed quickly and easily to support changing networking needs. 

SFP-equipped gear may be configured with different connector types (SC, LC, ST), fiber types (single-mode, multi-mode), cable configuration (simplex, duplex), and communications standards (Gigabit Ethernet, Fiber Channel). 

SFP transceivers are also designated by their transmission speed. SFP typically supports data rates up to 4.25 Gbps, whereas SFP+ (Enhanced Small Form-factor Pluggable) supports data rates up to 10 Gbps for Ethernet. There are many other types with increasingly robust data transmission capabilities: SFP28, SFP56, SFP112, QSFP, QSFP+, QSFP28, QSFP56, and QSFP112. 

Where might you need an SFP? Frame synchronization is just one of many fiber workflow components that can benefit from SFP. It’s why frame synchronizer products like AJA FS2, FS4, and FS-HDR support optional SFP modules for both fiber and coaxial connections, allowing the frame syncs to operate in both baseband and optical environments. By adding the appropriate SFP module, a facility can use a frame sync device whether single-mode fiber, multi-mode fiber, or coaxial cables are installed. In other words, SFPs allow facilities to use whatever cabling is already installed. 

Adding the appropriate SFP module enables the integration of fiber-equipped gear into a fiber-based workflow. For example, an SDI signal can be converted and transmitted over fiber to another piece of equipment, such as a frame sync, where various signal processing tasks – like frame rate conversion, format conversion, local genlock, or audio adjustments within the embedded stream – can be performed. After processing, the signal can either be output as baseband SDI or transmitted further over optical fiber to another device in the signal chain. This modular approach allows facilities to flexibly adapt their connectivity to specific workflow requirements without being limited by fixed interfaces. 

Without fiber transport, it’s more complex to drive signals from source devices over large distances. Similarly, it can be difficult to recover a weakened signal that has traveled such a distance over copper/coax, especially with the higher data rates of 3G-SDI or 12G-SDI. That’s why fiber optic transport is often employed when signals in a production environment have to traverse great distances.  

For example, in stadiums, signals from the in-stadium control room are often shared with the production truck at the truck dock, and vice versa. These signals must travel a great distance through the stadium to the frame sync device for frame synchronization and conversion into the proper video format, frame rate, color gamut, and dynamic range to satisfy the respective production requirements of the teams in the truck and the stadium.  

When investing in fiber, it’s important to consider your needs carefully to ensure the SFP you choose meets your requirements. Is future proofing a primary consideration? What infrastructure has already been installed at your facility, and does this product support it? How far will your signals typically have to travel between devices? In general, knowing the desired data rate and cable type will help you determine what connectivity your new device should include to be integrated smoothly into your existing workflow. The answers to these questions will help you decide which technology can help you achieve your goals.  

For more ideas on how you might leverage fiber in your infrastructure or tools that can help solve common fiber problems, check out our fiber in action page [hyperlink to fiber in action page]. And take a closer look at AJA’s fiber-equipped devices support, which support a range of SFPs to accommodate different data rates (3G-SDI or 12G-SDI), physical connectivity (fiber or coax), and fiber optic cable type (single-mode or multi-mode). 

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Across M&E and proAV, fiber workflows are ubiquitous for their many advantages. Whether you’ve already invested in fiber and are looking for tools to improve your workflow or are starting from the ground up, we encourage you to check out the compilation of stories and workflow diagrams below. They might spark an idea or two. If you have questions about fiber as you review these materials, contact [INSERT SALES or SUPPORT ALIAS].  

Trying to determine the best fiber tools for your facility, truck, or next project? Get inspiration from AJA customers leveraging fiber tools in the field every day. 

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