Description : Silica (pure glass) fibers are used because of their low intrinsic material absorption at the wavelengths of operation. This wavelength of operation is between two intrinsic absorption regions. What are these two regions called? What are the wavelengths of operation for these two regions?
Last Answer : Ultraviolet absorption region (below 400 nm) and infrared absorption region (above 2000 nm).
Description : In single mode operation, the value of the normalized frequency (V) should remain near the 2.405 level. If the value of V is less than 1, do single mode fibers carry a majority of the power in the core or cladding material?
Last Answer : Cladding material.
Description : Do small core distortions formed by arc fusion's self alignment mechanism have more of an affect on light propagating through multimode or single mode fibers?
Last Answer : Single mode fibers.
Description : The value of the normalized frequency parameter (V) relates the core size with mode propagation. When single mode fibers propagate only the fundamental mode, what is the value of V?
Last Answer : V≤2.405.
Description : How is the cutoff wavelength of a circular waveguide figured?
Last Answer : 1.71 times the diameter.
Description : List the types of materials used in fabricating low-loss, long wavelength optical fibers.
Last Answer : Heavy-metal fluorides, chalcogenide glasses, and crystalline materials.
Description : Will the cutoff wavelength of uncabled fibers (lcf) generally have a value higher or lower than the cutoff wavelength of cabled fibers (λcc)?
Last Answer : Higher.
Description : The cutoff wavelength of matched-clad and depressed-clad single mode fibers varies according to the fiber's radius of curvature and length. The cutoff wavelength of which single mode fiber type is more sensitive to length
Last Answer : Depressed-clad.
Description : Will an optical fiber's attenuation coefficient vary with changes in wavelength?
Last Answer : Yes.
Description : An absorption loss caused by valence electrons in the silica material from which fibers are manufactured. A. Modal dispersion B. Infrared absorption C. Ion resonance absorption D. Ultraviolet absorption
Last Answer : D. Ultraviolet absorption
Description : Multimode step-index fibers have relatively large core diameters and large numerical apertures. These provide what benefit?
Last Answer : Make it easier to couple light from a light-emitting diode (LED) into the fiber.
Description : In multimode step-index fibers, the majority of light propagates in the fiber core for what reason?
Last Answer : Most modes in multimode step-index fibers propagate far from cutoff.
Description : Multimode step-index fibers have a core and cladding of constant refractive index n1 and n2, respectively. Which refractive index, the core or cladding, is lower?
Last Answer : Cladding.
Description : List the standard core sizes for multimode step-index, multimode graded-index, and single mode fibers
Last Answer : Multimode step-index fibers: 50µm and 100µm. Multimode graded-index fibers: 50µm, 62.5µm, 85µm, and 100µm. Single mode fibers: between 8µm and 10µm.
Description : A mode filter is a device that attenuates specific modes propagating in the core of an optical fiber. What mode propagating along single mode fibers do mode filters eliminate?
Last Answer : Second-order mode.
Description : A single-mode cable does not suffer from: a. modal dispersion b. chromatic dispersion c. waveguide dispersion d. all of the above
Last Answer : a. modal dispersion
Description : What is the result of an abrupt change in the size, shape, or dielectric of a waveguide?
Last Answer : Reflections.
Description : ________ dispersion is caused by the difference in the propagation times of light rays that take different paths down a fiber. a. Material dispersion b. Wavelength dispersion c. Modal dispersion d. Delay dispersion
Last Answer : c. Modal dispersion
Description : Material dispersion is caused by the ∙ a. Wavelength dependence of the index of refraction ∙ b. Wavelength independence of the index of refraction ∙ c. Dependence of the propagation constant on the mode number ∙ d. Independence of the propagation constant on the mode number
Last Answer : d. Independence of the propagation constant on the mode number
Description : ______ dispersion is caused by the difference in the propagation times of light rays that take different paths down a fiber. ∙ a. Material dispersion ∙ b. Wavelength dispersion ∙ c. Modal dispersion
Last Answer : ∙ c. Modal dispersion
Description : Light travels faster in a material with a lower refractive index. Therefore, light rays that travel a longer distance in a lower refractive index travel at a greater average velocity. What effect does this have on multimode graded-index fiber modal dispersion and bandwidth?
Last Answer : Decreases the time difference between light rays, which reduces modal dispersion and increases fiber bandwidth.
Description : For efficient operation, should a detector have a high or low responsivity at the operating wavelength?
Last Answer : High.
Description : The size, shape, and dielectric material of a waveguide must be constant throughout its length for energy to move from one end to the other without reflections. What could be the effect in any abrupt change in its size or shape?
Description : What is the most likely cause of losses in waveguide systems?
Last Answer : Improperly connected joints or damaged inner surface.
Description : What is the most common type of waveguide joint?
Last Answer : Choke joint.
Description : A waveguide bend must have what minimum radius?
Last Answer : Greater than 2 wavelengths.
Description : When a waveguide is terminated in a resistive load, the load must be matched to what property of the waveguide?
Last Answer : . Characteristic impedance.
Description : What device is used to produce a gradual change in impedance at the end of a waveguide?
Last Answer : Horn.
Description : What is the result of an impedance mismatch in a waveguide?
Last Answer : Standing waves that cause power losses, a reduction in power handling capability, and an increase in frequency and sensitivity.
Description : Loose or inefficient coupling of energy into or out of a waveguide can be accomplished by the use of what method?
Last Answer : Slots and apertures.
Description : What determines the frequency, bandwidth, and power handling capability of a waveguide probe?
Last Answer : Size and shape
Description : Which subscript, in circular waveguide classification, indicates the number of full-wave patterns around the circumference?
Last Answer : First.
Description : The electric field is perpendicular to the "a" dimension of a waveguide in what mode?
Last Answer : TE.
Description : What field configuration is easiest to produce in a given waveguide?
Last Answer : . Dominant mode
Description : What term is used to identify the forward progress velocity of wavefronts in a waveguide?
Last Answer : Group velocity.
Description : incidence and reflection that are perpendicular to the waveguide walls?
Last Answer : Cutoff frequency.
Description : Assuming the wall of a waveguide is perfectly flat, what is the angular relationship between the angle of incidence and the angle of reflection
Last Answer : The angles are equal.
Description : When a wavefront is radiated into a waveguide, what happens to the portions of the wavefront that do not satisfy the boundary conditions?
Last Answer : Decrease to zero.
Description : What interaction causes energy to travel down a waveguide?
Last Answer : The interaction of the electric and magnetic fields.
Description : When the frequency is decreased so that two quarter wavelengths are longer than the "a" (wide) dimension of the waveguide, what will happen?
Last Answer : Energy will no longer pass through the waveguide.
Description : What happens to the bus bar dimensions of the waveguide when the frequency is increased?
Last Answer : The bus bar becomes wider.
Description : The frequency range of a waveguide is determined by what dimensions?
Last Answer : . The "a" dimension.
Description : The large surface area of a waveguide greatly reduces what type of loss that is common in two-wire and coaxial lines?
Last Answer : Copper loss.
Description : The folded waveguide in a bwo serves the same purpose as what component in a twt?
Last Answer : Helix.
Description : How does a waveguide-type lens focus spherical wavefront microwave energy?
Last Answer : Some wavefronts are accelerated so that all wavefronts exit the lens at the same time
Description : Optical fibers for telecommunications are typically about _____ mils thick and consists of a glass core, a glass cladding of lower index of refraction, and a protective coating ∙ a. 5 ∙ b. 6 ∙ c. 7 ∙ d. 8
Last Answer : ∙ a. 5
Description : Assertion : Rainbow is an example of the dispersion of sunlight by the water droplets. Reason: light of shorter wavelength is scattered much more than light of longer wavelength (a) Both A and R are true and R is the correct ... of A.(c) A is true but R is false. (d) A is false but R is true.
Last Answer : (c) A is true but R is false.
Description : Assertion (A) :Sunlight reaches us without dispersion in the form of white light and not as a component. Reason(R) : Dispersion takes place due to variation of refractive index for different wavelength but in vaccum the speed of ... of A. (c) A is true but R is false. (d) A is false but R is true.
Last Answer : (a) Both A and R are true and R is the correct explanation of A.
Description : Pick up the correct statement from the following: (A) The refractive index of a medium varies according to the wavelength of the radiation, (B) The variation of the refractive index with wave length, ... of white light by passing through a prism is caused due to dispersion (D) All of these
Last Answer : Answer: Option D
Description : Light rays that are emitted simultaneously from an LED and propagated down an optical fiber do not arrive at the far end of the fiber at the same time results to ∙ A. intramodal dispersion ∙ B. pulse length dispersion ∙ C. modal dispersion ∙ D. wavelength dispersion
Last Answer : D. wavelength dispersion