What is a fundamental necessity in the fabrication of fibers for light transmission?
1.Same refractive index for both core and cladding
2.Pump source
3.Material composition of fiber
4.Variation of refractive index inside the optical fiber
A combination of a FBG and optical isolators can be used to produce non-blocking optical wavelength division add/draw multiplexers.
1.True
2.False
A device which is made of isolators and follows a closed loop path is called as a ____________
1.Circulator
2. Gyrator
3.Attenuator
4.Connector
A GaAs injection laser with an optical cavity has refractive index of 3.6. Calculate the reflectivity for normal incidence of the plane wave on the GaAs-air interface.
1.0.61
2.0.12
3.0.32
4.0.48
A graded-index fiber has a core with parabolic refractive index profile of diameter of 30μm, NA=0.2, λ=1μm. Estimate the normalised frequency.
1.19.32
2.18.84
3.16.28
4.17.12
A homo-junction is an interface between two adjoining single-crystal semiconductors with different band-gap energies.
1.True
2.False
A multimode step index fiber has a normalized frequency of 72. Estimate the number of guided modes.
1.2846
2.2592
3.2432
4.2136
A single mode fiber has mode field diameter 10.2μm and V=2.20. What is the core diameter of this fiber?
1.11.1μm
2.13.2μm
3.7.6μm
4.10.1μm
A single-mode step-index fiber or multimode step-index fiber allows propagation of only one transverse electromagnetic wave.
1.True
2.False
A step-index fiber has core refractive index 1.46 and radius 4.5μm. Find the cutoff wavelength to exhibit single mode operation. Use relative index difference as 0.25%.
1.1.326μm
2.0.124μm
3.1.214μm
4.0.123μm
Absorption losses due to atomic defects mainly include ___________
1.Radiation
2.Missing molecules, oxygen defects in glass
3.Impurities in fiber material
4.Interaction with other components of core
An FBG is developed within a fiber core having a refractive index of 1.30. Find the grating period for it to reflect an optical signal with a wavelength of 1.33μm.
1.0.51 μm
2.0.58 μm
3.0.61 μm
4.0.49 μm
An optical fiber has a core radius 2μm and a numerical aperture of 0.1. Will this fiber operate at single mode at 600 nm?
1.Yes
2.No
An optical fiber has core-index of 1.480 and a cladding index of 1.478. What should be the core size for single mode operation at 1310nm?
1.7.31μm
2.8.71μm
3.5.26μm
4.6.50μm
At what temperature range, does the melting of multi components glass systems takes place?
1.100-300 degree Celsius
2.600-800 degree Celsius
3.900-1300 degree Celsius
4.1500-1800 degree Celsius
Fiber drawing using preform was useful for the production of graded index fibers.
1.True
2.False
For lower bandwidth applications ______________
1.Single mode fiber is advantageous
2.Photonic crystal fibers are advantageous
3.Coaxial cables are advantageous
4.Multimode fiber is advantageous
Graded index fibers produced by liquid-phase melting techniques are less dispersive than step-index fibers.
1.True
2.False
How many different categories are available for the methods of preparing optical glasses?
1.1
2.2
3.3
4.4
How many implementation methods are available for optical isolators?
1.One
2.Four
3.Two
4.Three
How many mechanisms are there which causes absorption?
1.One
2.Three
3.Two
4.Four
How many propagation modes are present in single mode fibers?
1.One
2.Two
3.Three
4.Five
How many types of hetero-junctions are available?
1.Two
2.One
3.Three
4.Four
How the potential macro bending losses can be reduced in case of multimode fiber?
1.By designing fibers with large relative refractive index differences
2.By maintaining direction of propagation
3.By reducing the bend
4.By operating at larger wavelengths
In the given equation, state what αr suggests?
1.Radius of curvature
2.Refractive index difference
3.Radiation attenuation coefficients
4.Constant of proportionality
It is a passive device which allows the flow of optical signal power in only one direction and preventing reflections in the backward direction.
1.Fiber slice
2.Optical fiber connector
3.Optical isolator
4.Optical coupler
Magneto-optic devices can be used to function as isolators.
1.True
2.False
Meridional rays in graded index fibers follow ____________
1.Straight path along the axis
2.Curved path along the axis
3.Path where rays changes angles at core-cladding interface
4.Helical path
Most of the optical power is carried out in core region than in cladding.
1.True
2.False
Numerical aperture is constant in case of step index fiber.
1.True
2.False
One of the given statements is true for intermodal dispersion. Choose the right one.
1.Low in single mode and considerable in multimode fiber
2.Low in both single mode and multimode fiber
3.High in both single mode and multimode fiber
4.High in single mode and low in multimode fiber
Optical fibers suffer radiation losses at bends or curves on their paths.
1.True
2.False
Plastic fibers are less widely used than glass fibers.
1.True
2.False
Population inversion is obtained at a p-n junction by __________
1.Heavy doping of p-type material
2.Heavy doping of n-type material
3.Light doping of p-type material
4.Heavy doping of both p-type and n-type material
Sharp bends or micro bends causes significant losses in fiber.
1.True
2.False
Skew rays follow a ___________
1.Hyperbolic path along the axis
2.Parabolic path along the axis
3.Helical path
4.Path where rays changes angles at core-cladding interface
The commercially available circulators exhibit insertion losses around ________________
1.2 dB
2.0.7 dB
3.0.2 dB
4. 1 dB
The difference between the modes’ refractive indices is called as ___________
1.Polarization
2.Cutoff
3.Fiber birefringence
4.Fiber splicing
The effects of intrinsic absorption can be minimized by ___________
1.Ionization
2.Radiation
3.Suitable choice of core and cladding components
4.Melting
The liquid-phase melting technique is used for the production of fibers ___________
1.With a core diameter of 50μm
2.With a core diameter less than 100μm
3.With a core diameter more than 200μm
4.With a core diameter of 100μm
The minute perturbations and impurities in the fiber drawing process using preform technique can result in very high losses of _____________
1.Between 500 and 1000 dB/km
2.Between 100 and 300 dB/km
3.Between 1200 and 1600 dB/km
4.More than 2000 dB/km
The ______________ system is best developed and is used for fabricating both lasers and LEDs for the shorter wavelength region.
1.InP
2.GaSb
3.GaAs/GaSb
4.GaAs/Alga AS DH
What is needed to predict the performance characteristics of single mode fibers?
1.The intermodal delay effect
2.Geometric distribution of light in a propagating mode
3.Fractional power flow in the cladding of fiber
4.Normalized frequency
What is the first stage in liquid-phase-technique?
1.Preparation of ultra-pure material powders
2.Melting of materials
3.Decomposition
4.Crystallization
What is the unit of normalized frequency?
1.Hertz
2.Meter/sec
3.Coulombs
4.It is a dimensionless quantity
Which equation is used to calculate MFD?
1.Maxwell’s equations
2.Peterman equations
3.Allen Cahn equations
4.Boltzmann’s equations
Which feature of an optical isolator makes it attractive to use with optical amplifier?
1.Low loss
2.Wavelength blocking
3.Low refractive index
4.Attenuation
Which materials are unsuitable for the fabrication of graded index fiber?
1.Glass-like-materials
2.Mono-crystalline structures
3.Amorphous material
4.Silica based material
Which of the following statements best explain the concept of material absorption?
1.A loss mechanism related to the material composition and fabrication of fiber
2.A transmission loss for optical fibers
3.Results in attenuation of transmitted light
4.Causes of transfer of optical power
Which processes are involved in the purification stage in liquid-phase-technique?
1.Filtration, Co-precipitation, Re-crystallization
2.Decomposition, Filtration, Drying
3.Doping, Drying, Decomposition
4.Filtration, Drying, Doping