Optical Communications Question Bank on “Optoelectronic Integration and Photonic Integrated Circuits”.
1. Monolithic integration for optical sources are confined to the use of __________ semiconductors.
a) Ⅲ-Ⅴ
b) Ⅱ-Ⅲ
c) Ⅰ-Ⅱ
d) Ⅶ-Ⅷ
Answer: a
Explanation: Ⅲ-Ⅴsemiconductor compounds are much useful. They possess both optical and electronic properties. These properties can be exploited to produce high performance devices.
2. Circuits fabricated from GaAs or AlGaAs operate in wavelength region of __________
a) 0.1 and 0.2 μm
b) 0.8 and 0.9 μm
c) 0.4 and 0.6 μm
d) 0.6 and 0.7 μm
Answer: b
Explanation: Circuits fabricated from GaAs use injection laser which is fabricated on GaAs with a MESFET. This is used to bias and modulate the laser.
3. The OEICs realization __________ as compared to the other developments in IO.
a) Scripted
b) Decreased
c) Lagged behind
d) Increased
Answer: c
Explanation: IO devices use dielectric materials such as lithium niobate. This lagging behind is caused by inherent difficulties in fabrication of OEICs even if Ⅲ-Ⅴ semiconductors are used.
4. Compositional and structural differences between photonic and electronic devices __________
a) Provide high efficiency
b) Provide low efficiency
c) Highly used
d) Create problems
Answer: d
Explanation: Compositional and structural differences cause epitaxial crystal growth, planarization for lithography, electrical interconnections. They also cause thermal and chemical stability of materials, electric matching and heat dissipation.
5. To avoid large chip __________ devices are used.
a) InGaAsP
b) InGa
c) GaAs
d) InGaAs
Answer: a
Explanation: To avoid large chip, InGaAsP devices are used with directly modulated semiconductor lasers. This gives good dynamic characteristics at 40 Gbit/s at 1.55 μmwavelength.
6. Devices operating at transmission rates greater than 40 Gb/s are _________
a) GaAs and InP
b) GaAs
c) InGa
d) InGaAs
Answer: a
Explanation: Optoelectronic integrated circuits are based on heterojunction bipolar transistor and electron mobility transistor use GaAs and InP. These are capable of operating at transmission rates higher than 40 Gb/s.
7. HEMT based __________ have a spot-size convertor with a photodiode.
a) p-n junction diode
b) p-i-n photoreceiver
c) IGBT
d) BJT
Answer: b
Explanation: P-I-N photoreceiver comprises of spot-size convertor with a photodiode. Spot-size convertor increases fiber alignment tolerances by one order of magnitude. This enables use of cleaved instead of lensed fiber.
8. P-I-N photoreceiver based on HEMT is integrated with _________ guiding layers.
a) GaAs and InP
b) GaAs
c) InGa
d) InGaAsP
Answer: d
Explanation: P-I-N photoreceiver is integrated with InGaAsP guiding layers. In this HEMT based technology, InGaAsP provides more confinement.
9. An optical power splitter integrated with optical waveguide amplifier is more useful.
a) True
b) False
Answer: a
Explanation: The aim of optical waveguide amplifier is to reduce the number of amplifiers in system. Alongwith, it also reaches maximum number of nodes.
10. The use of intelligent optical switches is necessary.
a) False
b) True
Answer: b
Explanation: Most applications of OEICs in optical networks require large switching capacity to support a large number of WDM channels. This also provides control of both optical signal wavelength and signal power.
11. The wafer scale replication technology uses ____________
a) SOL gel
b) GaAs
c) InGa
d) InGaAsP
Answer: a
Explanation: Replication technology employs hot embossing, molding and ultraviolet lithography. Ultraviolet curable SOL gel enables refractive and diffractive micro-optical elements to be replicated directly on glass substrates.
12. ___________ is useful for production of both planar micro-optical elements and stacked optical microsystems.
a) Wavelength amplifier
b) Wavelength convertor
c) Replication technology
d) Optical switching matrix
Answer: c
Explanation: SOL gel materials used in replication technology allows combination of replication with lithography. This leaves selected areas material-free for sawing and bunding.
13. Optical interconnection between optoelectronic device is achieved in _________
a) Wavelength amplifier
b) Wavelength convertor
c) Replication technology
d) Chip-to-chip interconnection
Answer: d
Explanation: The chip-to-chip interconnection of optical components have a vertical cavity surface-emitting laser. These are assembled in micro-trenches in which embedded electrodes are connected through passive junction of poliver waveguide on alignment pits.
14. Multilevel interconnections are incorporated in _______
a) PIC
b) AWG based coupler
c) Convertors
d) OEIC technologies
Answer: a
Explanation: PIC reduces the overall size of optical functions. This causes the interconnection of several modules growing on same substrate.
15. When there is M number of WDM channels present at N input ports, then the output port 1 produces a _________
a) CW signal
b) WDM signal
c) Amplified signal
d) Distorted signal
Answer: b
Explanation: The reconstituted spectrum of WDM signal at any output port consists of a different set of wavelength channels with at least one wavelength channel from each input port producing a WDM signal having wavelength signal from each of input ports.
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