1.0.9 to 1.2 ns/km
2.0.2 to 1 ns/km
3.0.23 to 5 ns/km
4.0.45 to 8 ns/km
_________ can potentially provide spectral conservation through the use of multilevel signalling.
A 4 km optical link consists of multimode step index fiber with core refractive index of 1.3 and a relative refractive index difference of 1%. Find the delay difference between the slowest and fastest modes at the fiber output.
A decibel may be defined as the ratio of input and output optical power for a particular optical wavelength.
A device that reduces the intensity of light in optical fiber communications is ___________
A multimode fiber has RMS pulse broadening per km of 12ns/km and 28ns/km due to material dispersion and intermodal dispersion resp. Find the total RMS pulse broadening.
A multimode step-index fiber has a core refractive index of 1.5 and relative refractive index difference of 1%. The length of the optical link is 6 km. Estimate the RMS pulse broadening due to intermodal dispersion on the link.
1.Makes an angle equal to acceptance angle with the axial ray
2.Makes an angle equal to critical angle with the axial ray
3.Travels parallel equal to critical angle with the axial ray
4.Makes an angle equal to critical angle with the axial ray
An alternative modification of the dispersion characteristics of single mode fibers involves achievement of low dispersion gap over the low-loss wavelength region between __________
1.0.2 and 0.9μm
2.0.1 and 0.2μm
3.1.3 and 1.6μm
4.2 and 3μm
1.Effective R-I and core geometry
3.Transmission/propagation time of waves
4.Refractive indices of glass and silica
Beat length of a single mode optical fiber is 0.6cm. Calculate the difference between propagation constants for the orthogonal modes.
Consider a single mode fiber having core refractive index n1= 1.5. The fiber length is 12m. Find the time taken by the axial ray to travel along the fiber.
1.Increasing fiber core diameter and decreasing fractional index difference
2.Decreasing fiber core diameter and decreasing fractional index difference
3.Decreasing fiber core diameter and increasing fractional index difference
4.Increasing fiber core diameter and increasing fractional index difference
Disturbance along the fiber such as vibrations, discontinuities, connectors, splices, source/detectors coupling result in __________
Estimate RMS pulse broadening per km due to intermodal dispersion for multimode step index fiber where length of fiber is 4 km and pulse broadening per km is 80.6 ns.
External modulation for ________ modulation format allows the most sensitive coherent detection mechanism.
For many applications that involve optical fiber transmission, an intensity modulation optical source is not required.
For suitable power confinement of fundamental mode, the normalized frequency v should be maintained in the range 1.5 to 2.4μm and the fractional index difference must be linearly increased as a square function while the core diameter is linearly reduced to keep v constant. This confinement is achieved by?
1.Increasing level of silica doping in fiber core
2.Increasing level of germanium doping in fiber core
3.Decreasing level of silica germanium in fiber core
4.Decreasing level of silica doping in fiber core
If the input power 100μW is launched into 6 km of fiber, the mean optical power at the fiber output is 2μW. What is the overall signal attenuation through the fiber assuming there are no connectors or splices?
In index-guided photonic crystal fiber structure, the dark areas are air holes. What does white areas suggests?
Intermodal dispersion occurring in a large amount in multimode step index fiber results in ____________
1.Propagation of the fiber
2.Propagating through the fiber
3.Pulse broadening at output
4.Attenuation of waves
ny amount of stress occurring at the core-cladding interface would be reduced by grading the material composition.
The differential attenuation of modes reduces intermodal pulse broadening on a multimode optical link.
The digital transmission on implementation of polarization modulation which involves polarization characteristics of the transmitted optical signal is known as _____________
1.Frequency shift keying
2.Amplitude shift keying
3.Phase shift keying
4.Polarization shift keying
The fibers which relax the spectral requirements for optical sources and allow flexible wavelength division multiplying are known as __________
1.Dispersion-flattened single mode fiber
2.Dispersion-enhanced single mode fiber
3.Dispersion-compressed single mode fiber
4.Dispersion-standardized single mode fiber
The high index contrast enables the PCF core to be reduced from around 8 μmin conventional fiber to ___________
1.Less than 1μm
2.More than 5μm
3.More than 3μm
4.More than 2μm
The line width in the range ________ of bit rate is specified for ASK heterodyne detection.
2.2 to 8%
3.10 t0 50%
1.Decreasing width of signal longitudinal mode
2.Increasing coherence time
3.Decreasing number of longitudinal modes
4.Using fiber with large numerical aperture
The optical fiber incurs a loss in signal power as light travels down the fiber which is called as ___________
The periodic arrangement of cladding air holes in photonic band gap fibers provides for the formation of a photonic band gap in the ___________
1.H-plane of fiber
2.E-plane of fiber
3.E-H-plane of fiber
4.Transverse plane of fiber
The signals which are obtained by encoding each quantized signal into a digital word is called as
4.Sampling and quantization
1.Dispersion flattened fiber
When the input and output power in an optical fiber is 120μW & 3μW respectively and the length of the fiber is 8 km. What is the signal attenuation per km for the fiber?
___________ offers the potential for improving the coherent optical receiver sensitivity by increasing the choice of signalling frequencies.
2.Digital intensity modulation