光纤通信复习题范例

光纤通信复习题范例：
注：这里仅仅给出范例，考试范围以复习提纲为准！
一、简答/计算
1、What are the advantages and drawbacks of fiber-optic communications?
2、What does the term transparent windows mean? Specify three peak wavelength for the transparent windows in modern optical fibers.
3、Find the maximum transmission distance for a fiber link with attenuation of 0.3dB/km if the power launched in is 3mW and the receiver sensitivity is o.1mW?
4、Explain what is chromatic dispersion?
5、When does stimulated emission occur? How does stimulated emission occur?
6、What are the advantages and disadvantages of internal and external modulation?
7、Explain the principle of operation of an electroabsorption modulator.
8、explain the principle of operation of an EDFA.
9、What is the cutoff wavelength of a photodiode? What is the physical reason for the existence of a cutoff wavelength?
10、List four advantages of using reverse bias in a photodiode.
11、What is the sensitivity of a photodiode used in a fiber-optic communications system?
二、选择
1) Which is not the character of a laser diode compared to LEDs:
A) Monochromatic
B) Well directed
C) good linearity
D) Coherent
2) Which is not the character of semiconductor amplifiers compared to EDFAs:
A) Polarization dependent gain
B) Low gain
C) High noise
D) high coupling efficiency to the fiber
3) The time for free charges to move across the depletion region is called ( )
A) transit time B) response time C) rising time D) A, B, C are all incorrect
4) Good connectors have losses on the order of ( ).
A) 0.03 dB B) 0.3 dB C) 3 dB D) 30 dB
5) Preparation of the fiber end is required for
A) Splices
B) Connectors
C) Coupling from light source to the fiber
D) A, B, C are all correct
6) Thermoelectric coolers in LD modulators can
A) stabilize operating wavelength
B) stabilize operating output power of lasers
C) improve signal noise ratio
D) maintain fixed temperatures
7）FWM is most detrimental to optical communication system when ( ).
A) D(λ) = 0 B) D(λ) > 0 C) D(λ)<0, D) A, B, C are all incorrect.
8）All losses in optical fibers can be classified in two general categories: intrinsic and extrinsic. Which are not extrinsic losses? ( ).
A) Absorption B) Microbending losses
C) Rayleigh scattering D)Macrobending losses
coupler has one input port and 16 output ports, all output ports are equal.
9）. A 116
If the input signal power is -10dBm，then the power of one output port is ( ). ( ignoring the excess lose of the coupler)
A) -12dBm B)-20dBm C)-22dBm D)-26dBm
10）. The difference in refractive index can be achieved by doping silica with different dopants in optical fiber. If we want to decrease the refractive index, we dope silica with ( ).
A) GeO2, B) P2O5 C) B2O3, D) SiO2
11）. In singlemode fiber, with the wavelength decreasing, the MFD is ( ).
A) increasing B) decreasing
C)fixed D) A, B, C are all incorrect。