Chapter 3 - Theory Flashcards
Fiber with a ______ numerical aperture have a _________ bandwidth capability due to greater pulse spreading. Called modal dispersion.
Large; smaller
The bending of a beam of light in transmission between two dissimilar lights.
Refraction
Index of refraction
1.471 (miles and kilometers per second)
When a light beam changes direction at an interface, between two dissimilar media and reflects back into the medium from which it originated.
Fresnel Reflection
The sum of all reflections in a fiber span, including all component reflections and the Rayleigh backscatter of the optical fiber.
Optical Return Loss
Reflectance and ORL are expressed in
dB
Fiber optics typically uses wavelengths that are transmitted from which wavelength range?
770 nm to 1675 nm wavelength
Nanometers most commonly used in fiber optics?
850, 1300, 1310, 1550, 1625
Are infrared regions visible to the human eye?
Yes
The _____________ is different at each wavelength.
Speed of light
Loss of signal power
Attenuation
Core and cladding ovality is ____________
Fiber Geometry
When transmission loss increases because the fiber radius has decreased to the point that light rays begin to pass through the cladding boundary.
Macrobending
Manufactured using existing G.652 fiber specifications and are ideal for fiber to the building.
Bend-insensitive single-mode fibers
Lowest losses and reflections are created by having the fibers in contact or near contact.
End Separation
What does VCSEL Source stand for?
Vertical-cavity surface - emitting laser as source
What fiber is constructed with a core that has hundreds of concentric layers of glass between the center of the core and the cladding?
Graded-index Lightwave Propagation Multimode Fiber
What is Chromatic dispersion?
Different wavelengths travel at different speeds, leading to unequal amounts of bending.
What is a multimode issue that limits bandwidth?
Modal dispersion
What does the number of modes in a fiber do as the wavelengths decrease?
The number of modes increases
The _________ the fiber’s numerical aperture, the greater the effect of DMD.
Larger
Which wavelength has the lowest attenuation?
1550nm
What part of the electromagnetic spectrum is used by fiber optic systems?
Infrared Light Region
What is the bending of light called?
Refraction
What type of reflection is caused by an air gap in the connector pair?
Fresnel
What are three ways to reduce modal dispersion in a multimode system?
LED, VCSEL, Graded-index fiber
True or False: All wavelengths travel at the same speed through the fiber.
False
What type of dispersion effects multimode fiber and is a direct relation to the larger core size?
Modal dispersion
