Fiber patch cables, also known as fiber patch cords, or fiber jumpers, play an indispensable role in fiber optic cabling, widely used in CATV, FTTH, LAN, fiber optic sensors, server rooms, data centers, optical fiber connected & transmitted apparatus, fiber patch panels, fiber optic switches, etc. Due to the variety of fiber jumpers, novices are likely to make mistakes in picking up the most suitable one. In response to this, we’d like to introduce some basic knowledge of fiber patch cables in case it would be helpful for someone.
What is Fiber Patch Cord?
Compared with a fiber pigtail with only one end terminated with a fiber connector, a fiber patch cord has both ends terminated with connectors, often used to connect a patch panel with active equipment or two switch ports.
Figure 1: SC fiber optic patch cord with single-mode fiber
- Low insertion loss
- Low back reflection/high reflection loss
- High mating cycles
- Standardization and interchangeability
- Environmental-oriented design
Types of Fiber Patch Cords
We could classify fiber patch cords in terms of lots of standards. For example, we could divide them by fiber cable mode, fiber cable structure, jacket material, connector types, polishing types, jacket diameter, etc. Let’s present common types of fiber jumpers first.
Common Types of Fiber Patch Cables
Those most used fiber patch cables generally refer to those in which both ends are preinstalled with standard fiber connectors, such as LC, SC, ST, FC, E2000, and MTP/MPO types of fiber connectors. As for full details of these frequently used fiber connectors, you would know them in the 25 most important types of fiber optic connectors if you like.
Most fiber patch cords are pre-terminated with the same type of fiber connectors, like SC-SC, and LC-LC, although a few are fitted with hybrid connectors, like LC-SC.
Then let’s look at some specific designs of fiber patch cords.
Armored Fiber Jumper
This fiber patch cable has double tubing, namely an elastic stainless-steel tube inside the outer jacket. This design enables its resistance to pressure so that it could withhold an adult’s weight, not to mention rodents’ biting. More robust and rugged while keeping all the features of the standard fiber patch cords.
Figure 2: Armored Fiber Jumper
Bend Insensitive Fiber Patch Cable
As its name implies, this kind of fiber patch cord is little sensitive to stress and bending, featuring a short bending radius, keeping it away from bends due to its core design and low macro-bending sensitivity. As a result, it is ideal for FTTH or high-density applications in narrow corners.
Figure 3: Bend Insensitive Fiber Patch Cable
Low Insertion Loss Fiber Patch Cable
This kind of fiber jumper is specially selected to ensure the tightest fit for the fiber and best concentricity to produce relatively low insertion loss.
Figure 4: Low Insertion Loss Fiber Patch Cable
Mode-Conditioning Fiber Patch Cord
As a duplex multimode fiber jumper, it is designed to accommodate existing multimode cabling with longer distances and better signal quality. At the beginning of its transmission channel, there is a short length of single-mode fiber cable, which is to be fusion spliced with a multimode fiber cable. By aligning the single-mode launch away from the center of the multimode fiber core, the Differential Mode Delay effect is to be eliminated, therefore solving the technical issues.
Figure 5: Mode-Conditioning Fiber Patch Cord Working Principle
Switchable Fiber Patch Cord
This kind of fiber jumper has a unique design that allows for switching polarity without tools or re-termination, enabling an easy and fast polarity conversion, widely used in a high-density cabling environment with space limited.
Figure 6: Switchable Uniboot Fiber Patch Cable
Uniboot Fiber Patch Cord
These fiber jumpers merge two fibers into a single connector at both ends, usually terminated with deliberately designed LC Uniboot connectors. Its main draw lies in its high adaptability in a high-density environment because it spares half the previously needed fiber count, ideally suitable for tight space.
Figure 7: Uniboot Fiber Patch Cord
The types of fiber jumpers mentioned above are categorized by their daily use. Also, we could classify them from other specific perspectives.
By Cable Mode: Single-mode vs. Multimode fiber patch cords
There’re two kinds of fiber patch cables, i.e., single-mode and multimode fiber jumpers.
A single-mode fiber only carries a single mode of light, so it can transmit data over long distances with little attenuation of signal quality, which is impossible for multimode fiber. Therefore, a multimode fiber patch cord is used in short-distance transmission.
Typically, a single-mode fiber patch cable has a 9 µm core diameter, while a multimode fiber patch cable has a 50µm or 62.5µm core diameter.
Usually, a single-mode fiber patch has a yellow-colored jacket, while a multimode fiber patch has an orange-colored or aqua-colored jacket.
By Cable Structure: Simplex vs. Duplex vs. Ribbon fan-out cable assembly
Simplex means a one-way light channel, used as either transmission or reception. A simplex fiber patch cable only consists of a single strand of fiber.
Duplex means a bi-directional or two-way channel, both transmission, and reception are included.
Ribbon fan-out cable assembly has multi-strands of fibers, and these fibers are terminated with one MPO/MTP connector at one end, while at the other end are fitted with lots of discrete connectors, like LC, SC, etc.
Figure 8: Ribbon fan-out cable assembly
By Jacket Material: PVC vs. LSZH vs. OFNP
There are three kinds of plating material, namely PVC, LSZH, and OFNP, respectively.
PVC stands for polyvinyl chloride, tolerant of oxidation and degradation, suitable for horizontal runs between the tables.
LSZH refers to Low Smoke Zero Halogen, using a fire-resistant coating and features low smoke, low toxicity, and low corrosion. Like PVC, it also fits for horizontal runs between the floors.
OFNP is the acronym for Optical Fiber Nonconductive Riser, designed for vertical runs between floors and other applications.
Which one to choose is up to your requirements of fiber cabling.
Figure 9: PVC vs. LSZH vs. OFNP Cable Jacket
By Jacket Diameter(mm): Ø3, Ø2, Ø1.6, Ø0.9
Fiber jumpers come in various jacket diameters, like Ø3, Ø2, Ø1.6, and Ø0.9 mm. Needless to say, where space is scarce, thinner jackets are preferable. Accordingly, thicker jackets imply more rigid.
Figure 10: 2mm vs. 3mm fiber core diameter
By Polishing Type: PC vs. UPC vs. APC
To reduce the insertion loss and improve the return loss, technicians have developed these three kinds of polish technologies.
PC refers to Physical Contact, having a typical back reflection <-40dB, available for both single-mode and multimode.
UPC stands for Ultra Physical Contact, having a typical back reflection <-50dB, and is for single-mode applications only.
APC is the acronym for Angled Physical Contact, having a typical back reflection <-60dB, and is for single-mode applications only.
The industry standard of return loss is at least −40 dB for PC, −50 dB for UPC, and −60 dB for APC. Normally, an APC connector has a better termination quality than a UPC connector, but APC is not as cheap as UPC. Generally, the APC patch cable is green-colored, and the UPC patch cable is blue-colored.
We’ve talked about the fundamental knowledge of fiber jumpers. Though discussed not in detail, we sincerely hope it would help newbies to telecommunication. Maybe after reading, you will be able to pick up your most suitable fiber jumper.
We’ve been continuing a series of Introductory knowledge sharing on fiber optics. Stay tuned.
How to choose the fiber jumper? (Will be released soon)