Welcome, let's brush up on some Fiber basics.
As fiber first rolled out, fiber splicing was as much art as function, microscopes and cameras were bulky, LED's were expensive and each fusion splicer hand tuned. The machines modernized with the industry with better CCTV cameras, smaller mirrors, more automatic positioning techniques -- the original form may have shrunken but has remained virtually unchanged as economy of scale techniques have been used to bring down overall system prices.
Not a huge surprise when you consider most product testing is done in a lab environment by lab techs for white coat inspectors. In our service lab we see a dozen different splicers from as many as seven different manufacturers every day: profile alignment, LID, core alignment, V-groove, 60 pound beasts from the early days, and even today's small "handhelds" that splice a dozen times and then beg for a new battery.
With brighter LED's why are there still mirrors to clean? With the advent of better definition CCTV chips why are multiple cameras still required? With a steady movement toward uniformity of raw fiber production, why are all the dust attracting gels, sprays and clamps even necessary anymore?
A fiber splicer's laboratory is his or her truck, or its tailgate on a good weather day. With the plethora of units available for sale these days, it's hard to determine what features and tech you need.
If you’re new to fiber or just brushing up before your next project bid -- here are some common fiber optic basics.
Let's dive into some Fiber basics to help you become more familiar.
EasySplicer Pro & MK2 Arc-Fusion Fiber Splicers
The basics: Type of Fiber
What is Optical Fiber?
Fiber is made up of a core surrounded by a cladding layer. Both are glass but each has its own index of refraction.
Basic Types of Optical Fiber
In use today are two general types of optical fiber:
Singlemode (SM) fiber is designed for use with a signal of one wavelength of light, typically at invisible 1310, 1480, 1550 or 1625nm wavelengths. Most often with a core diameter of 250µ (micron), singlemode fiber is commonly used for long distance regional or inter-city transmissions of data.
Multimode (MM) fiber is based on the ability to combine different wavelength signals in the same fiber path, typically at invisible 850 or 1300nm wavelengths. Most often with a core diameter of 900µ (micron), multimode fiber is commonly used for short distance curb to house, or patch cable transmissions of data.
Fiber Fundamentals
Fiber optic lines are made up of a core surrounded by a cladding layer. Both are glass but each has its own index of refraction. The light signal is applied to the end of the optical fiber and then bounces down the optical path.
Singlemode fiber is designed for use with a signal of one wavelength of light, typically at an invisible 1310 nm, 1480 nm, 1550 nm or 1625 nm wavelengths.
Multimode fiber is based on the ability to combine different wavelength signals in the same fiber path, typically at an invisible 850 nm or 1300 nm wavelength.
Common signal connection between transmission systems use ST or SC for multimode (generally jacketed in orange protective cabling), ST, SC, FC and LC for singlemode (generally jacketed in yellow protective cabling). Angled connectors are also prevalent in cable video applications: ASC or AFC (generally color coded green for quick identification).
Typical multimode connection losses are 0.2 to 0.5 dB, singlemode connection losses typically 0.5 to 1.0 dB - this is why even today so many inside applications show a preference for multimode connections requesting pigtailing.
Joining Fiber Optic Cables
There are two ways to join fiber optic cable (working with glass fiber, of course, you can't twist it together or tie it in a square knot):
Mechanically - Two finely polished fiber ends are mated in a mechanical device with a small amount of index matching gel.
Arc fusion - Simply cleaving and melting the two fiber ends into one solid glass fiber to ensure minimal loss.
Typical mechanical connection losses are 0.3 dB and fusion are 0.03 dB. These losses, plus the typical loss of the fiber type you are using should fall within the loss budget.
Fiber vs. the Twisted Pair
Fiber vs. the Twisted Pair
Fiber vs. the Twisted Pair
Used for the greater part of the last century, the “twisted pair” is a twisted thin gauge copper wire pair that only allows a single analog data connection. Today, twisted pairs are used in everything ranging from telephone wires to computer networking cables.
Twisted pairs rely on the use of hardware switching equipment to combine mass amounts of data to be carried over distances, and can be susceptible to interference and/or security concerns.
Revolutionizing the telecommunications industry, optical fiber strands transmit digital (binary) data at the speed of light. This throughput allows each individual fiber to transmit an incredible amount of data, for example tens-of-thousands of telephone calls. As an added bonus, optical fiber strands are very secure and immune to radio frequency interference.
However, unlike the twisted pair, to connect two separate fiber strands you cannot just simply twist them together. A mechanical or fusion splicer must be used to align the fiber cores in order to continue the transfer of data.
Mechanical Splice
Fiber vs. the Twisted Pair
Fiber vs. the Twisted Pair
Because fiber is glass, you cannot simply tie two optical fiber ends in a knot. There are two methods to properly “splice” two fiber ends together.
Mechanically - Two finely polished fiber ends are mated in a mechanical device with a small amount of index matching gel. The aligning of cores is very important (mismatches drastically increase fiber loss).
Mechanical Splices tend to be ugly resulting in larger loss from .2 and beyond.
An ideal core-aligned splice has 0.0 to 0.05 loss.
Arc Fusion Splice
Fiber vs. the Twisted Pair
Arc Fusion Splice
Fusion - Melting of the 2 fiber ends into one solid glass fiber ensuring core alignment and minimal loss.
- Two cleaved and cleaned fibers are core positioned between two fusion electrodes.
- The two fusion electrodes emit a precision arc of electricity to melt and fuse the two fiber ends together.
- Within seconds the two fiber ends are fused together resulting in a continuous fiber strand.
An ideal core-aligned splice has 0.0 to 0.05 loss.
Splicer Kits
Splicer Kits
Splicer Kits
Join the fiber and also provide a loss measurement of the splice, typically .02 db.
Various brands from manufactured globally. The most recognizable brands are Sumitomo, AFL / Fitel, EasySplicer, and Inno.
Some models cost much more because of additional features that may or may not be necessary for your requirements.
OTDR
Splicer Kits
Splicer Kits
Optical Time Domain Reflectometer
OTDRs come in three basic versions:
- Full size OTDR -- the highest performance with a full complement of features like data storage and printers.
- MiniOTDR -- provide the same type of measurements as a full OTDR, but with fewer features to trim the size and cost.
- Fault finders -- use the OTDR technique, but are greatly simplified to just provide the distance to a fault, making the instrument even more affordable and easier to use.
BRT or ORL
Splicer Kits
BRT or ORL
Measure the ratio between the optical power into a component or system to its reflected optical power (back reflection), in units of dB.
ORL's measure actual insertion loss, so a low number is good. BRT's display return loss so the higher the number the better.
Polishers
Light Sources
BRT or ORL
Precision cleaning for low loss fiber ends.
Talk Sets
Light Sources
Light Sources
Verify, with a crystal clear connection, communication with another servicer at the other end of the fiber.
Light Sources
Light Sources
Light Sources
Chosen for compatibility with the type of fiber in use (singlemode or multimode with the proper core diameter) and the wavelength desired for performing the test. A signal source is required for an optical loss measurement.
Power Meters
Attenuators & Fiber Scope
Attenuators & Fiber Scope
Calibrated to read in linear units (milliwatts, microwatts and nanowatts) and/or dB referenced to one milliwatt or one microwatt optical power.
The best meters offer a relative dB scale for laboratory loss measurements.
Attenuators & Fiber Scope
Attenuators & Fiber Scope
Attenuators & Fiber Scope
Attenuators are precision adjustment of the level of signal in fiber.
Fiber Scopes are hand held microscope with a universal adapter to inspect connectors more closely.
Visual Fault Locators
Attenuators & Fiber Scope
Visual Fault Locators
Cable breaks, bending losses caused by kinks in the fiber, bad splices, etc. can be quickly detected visually with a visible light source.