Deck 16: Laser Technology and Devices

Question 1

The lasing line-width of Fox-smith resonator is ____________________

A)less than 1 mhz
B)1 mhz
C)2 mhz
D)greater than 3 mhz

Answer 1

less than 1 mhz

Question 2

What is the widest tuning range obtained in optical fiber laser structure?

A)60 nm
B)80 nm
C)more than 100 nm
D)100 nm

Answer 2

more than 100 nm

Question 3

The mechanism which results from a refractive index change in the passive waveguide layer is called as

A)absorption
B)spontaneous emission
C)monolithic inversion
D)bragg wavelength control

Answer 3

bragg wavelength control

Question 4

How many sections are included in a sampling grating distributed Bragg-reflector laser (SG-DBR)?

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

Question 5

Fiber based lasers provide diffraction-limited power at higher levels than solid-state laser. State whether the given statement is true or false

Question 6

The parameters having a major role in determining threshold current of efficiency of injection laser are:

A)angle recombination and optical losses
B)frequency chirping
C)relaxation oscillation
D)mode hopping

Question 7

Auger current is mostly ___________________ for material with band gap providing longer wavelength emission.

A)unaffected
B)lesser
C)larger
D)vanishes

Question 8

Injection lasers operating in smaller wavelengths are subjected to increased carrier losses.

Question 9

Devices based on quaternary PbSnSeTe and their ternary compounds, emit at wavelength ?

A)between 3-4 ?m
B)longer than 4 ?m
C)between 3.5 to 4.2 ?m
D)between 2 to 3 ?m

Question 10

Replacing Sn with Eu, Cd or Ge in some _________________ the band gap.

A)remove the band gap
B)does not affect
C)decreases
D)increases

Question 11

Lasing obtained in __________ when 191 mW of pump light at a wavelength of 0.477 ?m is launched into laser.

A)ternary pbsnsete alloy laser
B)quaternary pbsnsete alloy laser
C)doped fluoro-zirconate fiber
D)ternary pbeute alloy laser

Question 12

The thulium doped fiber laser when pumped with alexandrite laser output at 0.786 ?m, the laser emits at

A)0.6 ?m
B)0.8 ?m
C)2.3 ?m
D)1.2?m

Question 13

The diode-cladding-pumped Erbium praseodymium-doped fluoride device operates at wavelength.

A)around 3 ?m
B)4 ?m
C)2.6 ?m
D)1.04 ?m

Question 14

A technique based on inter-sub band transition is known as

A)auger recombination
B)frequency chirping
C)inter-valence band absorption
D)quantum cascading

Question 15

In a QC laser, a same electron can emit number of photons.

Question 16

The phenomenon resulting in the electrons to jump from one state to another each time emitting of photon is known as :

A)inter-valence band absorption
B)mode hopping
C)quantum cascading
D)quantum confinement

Question 17

A QC laser is sometimes referred as:

A)unipolar laser
B)bipolar laser
C)gain guided laser
D)non semiconductor laser

Question 18

In QC lasers, it is possible to obtain different output signal wavelengths. This can be achieved by

A)inter-valence band absorption
B)mode hopping
C)quantum cascading
D)selecting layers of different thickness

Question 19

QC lasers ______________ the performance characteristics.

A)have negligible effects
B)does not affects
C)improves
D)degrades

Question 20

An MQW cascaded laser is more advantageous because of:

A)mode hopping
B)auger recombination
C)control over layers of material
D)properties of material

Question 21

The absence of _______________ in LEDs limits the internal quantum efficiency.

A)proper semiconductor
B)adequate power supply
C)optical amplification through stimulated emission
D)optical amplification through spontaneous emission

Question 22

The excess density of electrons ?nand holes ?pin an LED is

A)equal
B)?pmore than ?n
C)?n more than ?p
D)does not affects the led

Question 23

The hole concentration in extrinsic materials is _________ electron concentration.

A)much greater than
B)lesser than
C)equal to
D)negligible difference with

Question 24

In a junction diode, an equilibrium condition occurs when

A)?ngreater than ?p
B)?nsmaller than ?p
C)constant current flow
D)optical amplification through stimulated emission

Question 25

Determine the total carrier recombination lifetime of a double heterojunction LED where the radioactive and nonradioactive recombination lifetime of minority carriers in active region are 70 ns and 100 ns respectively.

A)41.17 ns
B)35 ns
C)40 ns
D)37.5 ns