I’ve been creating these quizzes for almost 10 years now, but in reviewing my list of past topics, I realized I have never done one on the basics of fiber optics. I’m going to give you a “cheat sheet” and introduce you to the new Fiber Optic Association (FOA) Online Fiber Optic Reference Guide (www.thefoa.org/tech/ref) that I have been working on for the FOA during the last year. Hint: all the answers can be found in the pages in the section “Fiber Optics, The Basics.” Answers and explanations are in red.
1. The biggest advantage of optical fiber is the fact it is the most cost- effective means of transporting information because __________.
A. Fiber transmits information faster than other methods over longer distances
B. Fiber is cheaper than copper wire
C. Fiber is easier to install
D. Electronics for fiber optics are cheaper
Fiber’s biggest advantage is its high bandwidth and low attenuation. www.thefoa.org/tech/ref/basic/basics.html
2. Identify the three parts of the optical fiber shown in the drawing above.
B. Primary buffer coating
Optical fiber is comprised of a light-carrying core surrounded by an optical cladding that traps the light in the core and a protective coating called the primary buffer coating. www.thefoa.org/tech/ref/basic/fiber.html
3. Even cell phone networks and municipal wireless (Wi-Fi) systems have fiber backbones.
Practically all communications networks use fiber optic backbones for the same reason mentioned in question 1. www.thefoa.org/tech/ref/basic/nets.html
4. In an optical fiber, the light is transmitted through the __________.
Light is transmitted through the core, trapped in the core by the cladding and the fiber is protected by the primary buffer coating and the cable jacket. www.thefoa.org/tech/ref/basic/jargon.html
5. Single-mode fiber has an optical core that __________.
A. Is composed of many layers of glass with small variations in composition
B. Is made of PMMA plastic
C. Is smaller than multimode fiber
D. Transmits visible light better than other fibers
The core of singlemode fiber is so small that light can only travel in one path, called a mode. www.thefoa.org/tech/ref/basic/fiber.html
6. When preparing glass fiber for termination or splicing, a fiber stripper removes the __________ of the fiber.
C. Primary buffer coating
A fiber stripper removes the primary buffer coating from the fiber to the glass fiber can be spliced or terminated. www.thefoa.org/tech/ref/basic/jargon.html
7. The wavelength of light used for most fiber optic systems is in the __________ region and __________ to the human eye.
A. Ultraviolet, invisible
B. Solar, visible
C. Infrared, invisible
D. Microwave, harmful
Most fiber optic systems use infrared light which has lower attenuation in the glass fiber, but is invisible to the human eye. www.thefoa.org/tech/ref/basic/jargon.html
8. __________ is the fiber specification most important to the installer in testing.
C. Numerical aperture
D. Core-cladding concentricity
Attenuation is the primary specification for optical fiber, and a contributor, along with connector and splice loss, to the loss of the installed cable plant. www.thefoa.org/tech/ref/basic/fiber.html
9. What wavelengths are appropriate for use with 50/125 or 62.5/125 micron multimode fiber?
A. 650 and 850 nm
B. 850 and 1,300 nm
C. 850 and 1,310 nm
D. 1,310 and 1,550 nm
Multimode fiber uses sources at 850 and 1300 nm so its performance is optimized for those wavelengths. www.thefoa.org/tech/ref/basic/fiber.html
10. Dangerous light from fiber optic cables is always bright and easily visible.
Since most optical fiber systems operate with infrared light which is invisible to the human eye, dangerous power levels such as those in some wavelength-division multiplexed or amplified systems can be dangerous, but will not be visible. www.thefoa.org/tech/ref/basic/basics.html
HAYES is a VDV writer and trainer and the president of The Fiber Optic Association. Find him at www.JimHayes.com.