It is no secret that there are multiple types of fiber patch cables and cords out there. This is also true of fiber optics, which occasionally requires such things to connect in certain situations. However, if you’re new to this, you might look at the catalog offered by a patch cable supplier and wonder which ones you actually need.
Fortunately, you don’t need to be completely lost. Different cables might exist and it might appear daunting to figure out which one does what, but there are only a few things you need to remember. When you sit down and start figuring out what sort of fiber patch cables you need, here are the guidelines to keep in mind.
Choose Connector Type
Your first consideration is what type you actually need. As noted, there is more than one type, and each one has some key physical differences. If you buy the wrong patch cable, you’ve basically wasted time and money, so figure that part out first.
A fiber optic patch cable has cords terminated at both ends, with varying types of connectors present. Some of them use different connectors on either end, meaning they’re intended to network two different devices. Those that use the same connectors are like ethernet crossover cables, meant to network two devices of the same type together.
The cables also have different intended functions. The 1.25mm LC cable is intended for high-intensity transmissions. For data and telecommunications functions, the 2.5mm SC is the recommended OTS cable. The 2.5mm ST and FC cables are also used in data and telecom functions, but the former sees more use in military applications and the latter in single-mode lasers and measurement. Finally, MPO/MTP is for multi-fiber ribbon applications.
Single-Mode or Multi-Mode?
The next consideration is modal. Do you want the cable to be single-mode or multi-mode? There are some key differences between the two, but the primary ones that should concern you are physical and functional.
Single-mode fiber patch cables use 9/125um glass fiber, often with a yellow fiber cable. This is the preferred cord for use in long-distance applications, such as data transmission and telecommunications. Multi-mode fiber uses either 50/125um or 62.5/125um, using orange or aqua as the main color of the fiber cable. These see use in shorter distance transmissions and functions.
Simplex or Duplex?
The third thing to remember is the difference between simplex and duplex. A simplex is a cable with only one cord, with a connector on each end. These are used for bidirectional transceivers. In contrast, the duplex is two cables put side by side. You’re going to see these in more common transceiver setups. Knowing which of these two you need is important, as the equipment will usually require one or the other.
Take a measurement of the area that the cable has to cover. Getting a cable that’s too short is problematic since it will usually mean you need to buy a new one instead. In general, getting more length of the cable than you actually need is a good idea. This gives you more leeway in case the device needs to move and you cover your bases in the event you measured incorrectly.
Connector Polish: APC vs UPC
It may not seem like it should matter, but connector polish is also something you should concern yourself with when selecting fiber patch cables. The concern is rooted in loss.
APC connectors have lower loss than UPC ones, in most cases. This means the optical performance of APC is better, so they see more use in fields like wavelength-division multiplexing and passive optical networks. In any capacity with a high sensitivity to loss, APC is the preferred choice.
However, UPC is much cheaper than APC. If the system is not as sensitive, UPC will usually not perform any less effectively. They are also a viable option if the application doesn’t require high-precision optical signals.
Finally, you should look at the three types of the cable jacket. Each one has its own features that make them ideal for certain functions or environments. If you don’t foresee these specific features coming into play or if you have a need for one over another, it helps to know beforehand. The three types are polyvinyl chloride, low smoke zero halogen (LSZH), and optical fiber nonconductive plenum (OFNP). There is also an uncommon fourth, called armored cable.
PVC jackets are meant to protect against physical degradation and oxidization. For areas that require the cable be flame-retardant or it is expected to be placed between floors, use LSZH. LSZH also has low toxicity in case the cable does burn. If the cable is going to be laid vertically, between spaces creating by components of a building within its main structure, you should use OFNP cable.
Armored cable uses double tubing and a steel sleeve, making these cables light-tight. This means that no light is able to escape the fibers, retaining the signal even when bent or twisted. They are designed to withstand tremendous pressure, so they are often used running along floors or other areas where they would be encounter regular impacts from footfalls and the like. The tubing is also resistant against cutting and abrasion, making them viable for use in some industrial environments.
There you have it; the six things you need to remember when choosing fiber patch cables. Regardless of the manufacturer, you need to take these into account before you buy. They are important details, and should not be overlooked.