NEETS Mod 24 - Fiber Optics Flashcards
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What do Ray theory and Mode theory describe?
How light energy is transmitted along an optical fiber.
What is the basic optical material property that measures the speed of light in an optical medium?
Index of Refraction
Which law describes the relationship between the incident and the refracted Ray’s when light Ray’s encounter the boundary between two different transparent materials?
Snell’s Law of Refraction
What are the 3 basic parts of an optical fiber?
Core, Cladding, Coating (Buffer)
What are Meridional Rays?
Light rays that pass through the axis of the optical fiber.
What are Skew rays?
Light rays that propagate through an optical fiber without passing through the axis.
What are Bound rays?
Light rays which propagate through an optical fiber core by total internal reflection.
What are Unbound rays?
Light rays that refract out of the fiber core into the cladding and are eventually lost.
What is total internal reflection?
When light rays are totally reflected at the boundary between two different transparent materials.
What is the Critical Angle of Incidence?
The angle at which total internal reflection occurs.
What is acceptance angle?
The maximum angle to the axis of the fiber that light entering the fiber is bound or propagated.
What is the measurement of the ability of an optical fiber to capture light?
Numerical Aperture (NA)
What uses electromagnetic wave behavior to describe the propagation of light along an optical fiber?
Mode Theory
What are the two classifications of optical fibers?
Single mode and Multimode
Define attenuation.
Loss of optical power as light travels along an optical fiber.
*Caused by absorption, scattering, & bending losses
Define dispersion.
Spreading the optical pulse as it travels along the fiber. (Limits how fast information is transferred)
What happens to light Ray’s when they encounter any substance?
Transmitted, Reflected, Refracted, or Absorbed.
When does reflection occurs?
When a wave strikes an object and it bounces back toward the source.
What is an incident wave?
The wave that from the source toward the object.
What is the reflected wave?
The wave that moves away from the object.
Define the Law of Reflection.
Law of Reflection states that the angle of incidence is equal to the angle of reflection.
What is Refraction?
When a wave traveling through two different mediums passes through the boundary of the mediums and bends toward or away from the normal.
What is the conversion of optical power into another energy form, such as heat?
Absorption
What are the two types of absorption?
Intrinsic and Extrinsic
What causes intrinsic absorption?
Basic fiber-material properties
What causes Extrinsic absorption?
When impurities, such as Hydroxyl ions, are introduced into the fiber material.
Which fibers are predominately used in fiber optic communication?
Silica fibers
What is the Wavelength of Operation in fiber optics?
Between 700nm and 1600nm
What is scattering?
Losses caused by the interaction of light with density fluctuations within a fiber.
What is the main source of loss in commercial fibers operating between 700nm and 1600nm?
Rayleigh scattering
What are the two types of dispersion?
Intramodal (Chromatic) and Intermodal (Modal)
What is the term used for light travelling through different materials and different waveguide structures at different speeds?
Intramodal (Chromatic) dispersion
True or False. Material dispersion is dependent on the light wavelengths interaction with the refractive index of the core.
True
Why does Intermodal (Modal) dispersion occur?
Because each more travels a different distance over the same time span.
What is the dominant source of dispersion in Multimode fibers?
Modal dispersion
Which fiber mode exhibits the highest possible bandwidth?
Single mode
