Deck 12: Yag Laser and Optical Fiber Communications

Question 1

 ____________________ lasers are presently the major laser source for optical fiber communications

A)semiconductor
B)non-semiconductor
C)injection
D)solid-state

Answer 1

injection

Question 2

In Nd: YAG lasers, the maximum doping levels of neodymium is ____________

A)0.5 %
B)1.5 %
C)1.8 %
D)2 %

Answer 2

1.5 %

Question 3

Which of the following is not a property of Nd: YAG laser that enables its use as an optical fiber communication source?

A)single mode operation
B)narrow line-width
C)long lifetime
D)semiconductors and integrated circuits

Answer 3

semiconductors and integrated circuits

Question 4

The Nd: YAG laser has a narrow line-width which is ________________

A)< 0.01 nm
B)> 0.01 nm
C)> 1 mm
D)> 1.6 mm

Question 5

The strongest pumping bands is a four level system of Nd: YAG laser at wavelength of range_________________

A)0.25 and 0.56 nm
B)0.75 and 0.81 nm
C)0.12 and 0.23 nm
D)1 and 2 nm

Question 6

The Nd: YAG laser is costlier than earth-doped glass fiber laser. State whether the following statement is true or false

Question 7

It is a resonant cavity formed by two parallel reflecting mirrors separated by a mirror separated by a medium such as air or gas

A)optical cavity
B)wheatstone's bridge
C)oscillator
D)fabry-perot resonator

Question 8

In a three level system, the threshold power decreases inversely with the length of the fiber gain medium.

Question 9

Which of the following co-dopant is not employed by neodymium and erbium doped silica fiber lasers?

A)phosphorus pent oxide
B)germania
C)nitrogen
D)alumina

Question 10

Dopants levels in glass fiber lasers are generally ___________

A)low
B)high
C)same as that of grin rod lens laser
D)same as that of semiconductor laser

Question 11

. _______________ fibers include addition of lead fluoride to the core glass in order to raise the relative refractive index.

A)solid-state
B)gaas
C)semiconductor
D)zblanp

Question 12

The lasing output of the basic Fabry-perot cavity fiber is restricted to between ____________

A)1 and 2 nm
B)5 and 10 nm
C)3 and 6 nm
D)15 and 30 nm

Question 13

In Fabry-perot laser, the lower threshold is obtained by

A)increasing the refractive index
B)decreasing the refractive index
C)reducing the slope efficiency
D)increasing the slope efficiency

Question 14

When did the non-semiconductor laser developed?

A)1892
B)1946
C)1985
D)1993

Question 15

Y3Al5 O12 Is a molecular formula for _____________

A)ytterbium aluminate
B)yttrium oxide
C)ytterbium oxy-aluminate
D)yttrium-aluminum garnet

Question 16

A perfect semiconductor crystal containing no impurities or lattice defects is called as

A)intrinsic semiconductor
B)extrinsic semiconductor
C)excitation
D)valence electron

Question 17

The energy-level occupation for a semiconductor in thermal equilibrium is described by the

A)boltzmann distribution function
B)probability distribution function
C)fermi-dirac distribution function
D)cumulative distribution function

Question 18

What is done to create an extrinsic semiconductor?

A)refractive index is decreased
B)doping the material with impurities
C)increase the band-gap of the material
D)stimulated emission

Question 19

_________________ is used when the optical emission results from the application of electric field.

A)radiation
B)efficiency
C)electro-luminescence
D)magnetron oscillator

Question 20

In the given equation, what does p stands for?

A)permittivity
B)probability
C)holes
D)crystal momentum

Question 21

Calculate the radioactive minority carrier lifetime in gallium arsenide when the minority carriers are electrons injected into a p-type semiconductor region which has a hole concentration of 1018cm-3. The recombination coefficient for gallium arsenide is

A)2ns
B)1.39ns
C)1.56ns
D)2.12ms

Question 22

Which impurity is added to gallium phosphide to make it an efficient light emitter?

A)silicon
B)hydrogen
C)nitrogen
D)phosphorus

Question 23

Population inversion is obtained at a p-n junction by

A)heavy doping of p-type material
B)heavy doping of n-type material
C)light doping of p-type material
D)heavy doping of both p-type and n-type material

Question 24

A GaAs injection laser has a threshold current density of 2.5*103Acm^?2and length and width of the cavity is 240?mand 110?m respectively. Find the threshold current for the device.

A)663 ma
B)660 ma
C)664 ma
D)712 ma