Deck 14: Semiconductor Laser Devices and Mechanisms

Question 1

Strip geometry of a device or laser is important.

Answer 1

True

Question 2

Better confinement of optical mode is obtained in

A)multi quantum well lasers.
B)single quantum well lasers.
C)gain guided lasers.
D)bh lasers.

Answer 2

multi quantum well lasers.

Question 3

Multi-quantum devices have superior characteristics over

A)bh lasers.
B)dh lasers.
C)gain guided lasers.
D)single-quantum-well devices.

Answer 3

dh lasers.

Question 4

Dot-in-well device is also known as

A)dh lasers.
B)bh lasers.
C)qd lasers.
D)gain guided lasers.

Question 5

A BH can have anything from a single electron to several electrons.

Question 6

QD lasers have a very low threshold current densities of range

A)0.5 to 5 a cm^?2
B)2 to 10 a cm^?2
C)10 to 30 a cm^?2
D)6 to 20 a cm^?2

Question 7

 __________________ may be improved through the use of frequency-selective feedback so that the cavity loss is different for various longitudinal modes.

A)frequency selectivity
B)longitudinal mode selectivity
C)electrical feedback
D)dissipated power

Question 8

Device which apply the frequency-selective feedback technique to provide single longitudinal operation are referred to as ________________

A)dsm lasers
B)nd: yag lasers
C)glass fiber lasers
D)qd lasers

Question 9

Which of the following does not provide single frequency operation?

A)short cavity resonator
B)dsm lasers
C)coupled cavity resonator
D)fabry-perot resonator

Question 10

Conventional cleaved mirror structures are difficult to fabricate with the cavity lengths below

A)200?mand greater than 150 ?m
B)100 ?m and greater than 50 ?m
C)50 ?m
D)150 ?m

Question 11

In the given equation, corrugation period is given by l?b/2Ne. If ?b is the Bragg wavelength, then what does 'l' stand for?

A)length of cavity
B)limitation index
C)integer order of grating
D)refractive index

Question 12

The first order grating (l=1) provide the strongest coupling within the device.

Question 13

The semiconductor lasers employing the distributed feedback mechanism are classified in _________________ categories

A)one
B)two
C)three
D)four

Question 14

DBF-BH lasers exhibit low threshold currents in the range of ________________

A)40 to 50 ma
B)21 to 30 ma
C)2 to 5 ma
D)10 to 20 ma

Question 15

Fabry-Perot devices with BH geometries high modulation speeds than DFB-BH lasers. State whether the given statement is true or false

Question 16

The InGaAsP/InP double channel planar DFB-BH laser with a quarter wavelength shifted first order grating provides a single frequency operation and incorporates a phase shift of ______________

A)?/2 radians
B)2? radians
C)? radians
D)3?/2 radians

Question 17

The narrow line-width obtained under the CW operation for quarter wavelength shifted DFB laser is ________________

A)2 mhz
B)10 mhz
C)3 mhz
D)1 mhz

Question 18

Line-width narrowing is achieved in DFB lasers by a strategy referred as _______________

A)noise partition
B)grating
C)tuning
D)bragg wavelength detuning

Question 19

_________________ is a technique used to render the non-conducting material around the active cavity by producing permanent defects in the implanted area

A)dispersion
B)ion de-plantation
C)ion implantation
D)attenuation

Question 20

The threshold temperature coefficient for InGaAsP devices is in the range of

A)10-40 k
B)40-75 k
C)120-190 k
D)150-190 k

Question 21

The process where the energy released during the recombination of an electron-hole event getting transferred to another carrier is known as

A)inter-valence bond absorption
B)auger recombination
C)carrier leakage effects
D)exothermic actions

Question 22

Auger recombination can be reduced by using

A)strained mqw structure.
B)strained sqw structure.
C)gain-guided strained structure.
D)strained quantum dots lasers.

Question 23

High strain in strained MCQ structure should be incorporated.

Question 24

The parameter that prevents carrier from recombination is

A)auger recombination
B)inter-valence band absorption
C)carrier leakage
D)low temperature sensitivity

Question 25

Determine the threshold current density for an AlGaAs injection laser with T0=180k at 30°C.

A)6.24
B)9.06
C)3.08
D)5.09