Deck 11: Optical Fiber Devices and Components

Question 1

Calculate the splitting loss if a 30×30 port multimode fiber star coupler has 1 mW of optical power launched into an input port.

A)13 db
B)15 db
C)14.77 db
D)16.02 db

Answer 1

14.77 db

Question 2

A _____________ coupler comprises a number of cascaded stages, each incorporating three or four-port FBT couplers to obtain a multiport output.

A)star
B)ladder
C)wdm
D)three-port

Answer 2

star

Question 3

A number of three-port single-mode fiber couplers are used in the fabrication of a ladder coupler with 16 output ports. The three-port couplers each have an excess loss of 0.2 dB along with a splice loss of 0.1 dB at the interconnection of each stage. Determine the excess loss.

A)1.9 db
B)1.4 db
C)0.9 db
D)1.1 db

Answer 3

1.1 db

Question 4

An FBG is developed within a fiber core having a refractive index of 1.30. Find the grating period for it to reflect an optical signal with a wavelength of 1.33?m.

A)0.51 ?m
B)0.58 ?m
C)0.61 ?m
D)0.49 ?m

Question 5

It is a passive device which allows the flow of optical signal power in only one direction and preventing reflections in the backward direction.

A)fiber slice
B)optical fiber connector
C)optical isolator
D)optical coupler

Question 6

Which feature of an optical isolator makes it attractive to use with optical amplifier?

A)low loss
B)wavelength blocking
C)low refractive index
D)attenuation

Question 7

Magneto-optic devices can be used to function as isolators.

Question 8

How many implementation methods are available for optical isolators?

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

Question 9

A device which is made of isolators and follows a closed loop path is called as a ____________

A)circulator
B)gyrator
C)attenuator
D)connector

Question 10

The commercially available circulators exhibit insertion losses around ________________

A)2 db
B)0.7 db
C)0.2 db
D)1 db

Question 11

A combination of a FBG and optical isolators can be used to produce non-blocking optical wavelength division add/draw multiplexers.

Question 12

A device which converts electrical energy in the form of a current into optical energy is called as

A)optical source
B)optical coupler
C)optical isolator
D)circulator

Question 13

How many types of sources of optical light are available?

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

Question 14

The frequency of the absorbed or emitted radiation is related to difference in energy E between the higher energy state E2 and the lower energy state E1. State what h stands for in the given equation?

A)gravitation constant
B)planck's constant
C)permittivity
D)attenuation constant

Question 15

The radiation emission process (emission of a proton at frequency) can occur in __________ ways.

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

Question 16

Which process gives the laser its special properties as an optical source?

A)dispersion
B)stimulated absorption
C)spontaneous emission
D)stimulated emission

Question 17

An incandescent lamp is operating at a temperature of 1000K at an operating frequency of 5.2×1014 Hz. Calculate the ratio of stimulated emission rate to spontaneous emission rate.

A)3×10^-13
B)1.47×10^-11
C)2×10^-12
D)1.5×10^-13

Question 18

The lower energy level contains more atoms than upper level under the conditions of ________________

A)isothermal packaging
B)population inversion
C)thermal equilibrium
D)pumping

Question 19

__________________ in the laser occurs when photon colliding with an excited atom causes the stimulated emission of a second photon.

A)light amplification
B)attenuation
C)dispersion
D)population inversion

Question 20

A ruby laser has a crystal of length 3 cm with a refractive index of 1.60, wavelength 0.43 ?m. Determine the number of longitudinal modes.

A)1×10²
B)3×10⁶
C)2.9×10⁵
D)2.2×10⁵

Question 21

A semiconductor laser crystal of length 5 cm, refractive index 1.8 is used as an optical source. Determine the frequency separation of the modes.

A)2.8 ghz
B)1.2 ghz
C)1.6 ghz
D)2 ghz

Question 22

Doppler broadening is a homogeneous broadening mechanism.

Question 23

An injection laser has active cavity losses of 25 cm^?1and the reflectivity of each laser facet is 30%. Determine the laser gain coefficient for the cavity it has a length of 500?m.

A)46 cm^?1
B)51 cm^?1
C)50 cm^?1
D)49.07 cm^?1

Question 24

Longitudinal modes contribute only a single spot of light to the laser output.

Question 25

Considering the values given below, calculate the mode separation in terms of free space wavelength for a laser.

A)1.4×10^-11
B)1.6×10^-12
C)1×10^-12
D)6×10^-11