2021 Optical Fiber Communications(Nanjing University of Posts and Telecommunications) 最新满分章节测试答案

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本课程起止时间为:2021-02-22到2021-06-28

Chap.2 Optical Fibers： Structures and Fabrication Test1

1、 问题:The core and cladding cannot be physically separated. 
选项：
A:正确
B:错误
答案: 【正确】

2、 问题:After the optical fiber is manufactured, its cut-off wavelength parameter can be determined. 
选项：
A:正确
B:错误
答案: 【正确】

3、 问题:The core and cladding are made of preformed wire. 
选项：
A:正确
B:错误
答案: 【正确】

Chap.3 Waveguide and Transmission Theory Test 2

1、 问题:Which of the following statements about the numerical aperture (NA) of an optical fiber is incorrect?
选项：
A:The larger the numerical aperture is, the better 
B:The smaller the numerical aperture is, the better 
C:The value is proportional to the optical fiber’s ability of accepting light
D:It reflects the coupling ability between the light source and the fiber
答案: 【The smaller the numerical aperture is, the better 】

2、 问题:Which of the following is the main cause of the nonlinear effect of optical fiber? 
选项：
A:Fiber ovality 
B:Input power of the optical signal 
C:Fiber bending 
D:Fiber length
答案: 【Input power of the optical signal 】

3、 问题:What is the main factor causing Rayleigh scattering? 
选项：
A:Defects equivalent to the wavelength scale of the fiber 
B:Defects equivalent to the geometric size of the fiber
C:Defects equivalent to the length of the fiber 
D:Impurities
答案: 【Defects equivalent to the wavelength scale of the fiber 】

Chap.4 Fiber Transmission Performance Test 3

1、 问题:The main cause of the energy attenuation of signal transmission in an optical fiber is the loss characteristics of the optical fiber. 
选项：
A:正确
B:错误
答案: 【正确】

2、 问题:The dispersion in multimode fiber is mainly the intermodal dispersion.
选项：
A:正确
B:错误
答案: 【正确】

3、 问题:The operating wavelength window with the smallest fiber transmission loss is near 1.55 μm.
选项：
A:正确
B:错误
答案: 【正确】

4、 问题:For the same optical fiber, the system with higher transmission rate is more sensitive to dispersion.
选项：
A:正确
B:错误
答案: 【正确】

5、 问题:Multi-channel systems are more susceptible to fiber nonlinearity than single-channel systems.
选项：
A:正确
B:错误
答案: 【错误】

Chap.5 Light Source Test 4

1、 问题:The function of the light source is to                         .
选项：
A:generate input light wave signal
B:convert electrical signal current into optical signal power, in other words, realize electrical-optical conversion
C:generate input optical power
D:use light waves modulate electrical signals so that their load information is transmitted in the fiber
答案: 【convert electrical signal current into optical signal power, in other words, realize electrical-optical conversion】

2、 问题:The key device to realize electric / optical conversion in optical transmitter is             .
选项：
A:Light source
B:Modulation circuit
C:Light detector
D:Amplifier
答案: 【Light source】

3、 问题:The P-I characteristic of LED is linear, so no matter whether it is modulated by analog signal or digital signal, no bias current is required. 
选项：
A:正确
B:错误
答案: 【错误】

Chap.6 Optical Transmitter Test 5

1、 问题:The role of adding a scrambler before the modulator of the system optical transmitter is to              .
选项：
A:Guarantee the transparency of transmission
B:Control the appearance of long strings "1" and "0"
C:Perform online error detection
D:Solve baseline drift
答案: 【Control the appearance of long strings "1" and "0"】

2、 问题:As the usage time of the semiconductor laser increases, its threshold current will be                    .
选项：
A:gradually decrease
B:remain unchanged
C:gradually increase
D:gradually increase then gradually decrease
答案: 【gradually increase】

3、 问题:The purpose of scrambling code is to make it easy to transmit the signal over the line. 
选项：
A:正确
B:错误
答案: 【错误】

Chap.7 Photodetectors Test 6

1、 问题:Which of the following statements relating to the bias voltage of PIN and APD is correct? 
选项：
A:Both are forward-biased
B:Both are reverse-biased
C:The former is forward-biased and the latter is reverse-biased
D:The former is reverse-biased and the latter is forward-biased
答案: 【Both are reverse-biased】

2、 问题:The noise of the photodetector includes quantum noise, dark current noise, leakage current noise and multiplication noise of            .
选项：
A:Light emitting diode
B:Avalanche photodiode
C:Double base diode
D:Mixing diode
答案: 【Avalanche photodiode】

3、 问题:Which of the following physical quantity describes the optical-to-electric conversion efficiency of the photodetector                .
选项：
A:Responsivity
B:Sensitivity
C:Extinction ratio
D:Gain
答案: 【Responsivity】

Chap.8 Optical Receiver Test 7

1、 问题:The main quality index of the optical receiver is sensitivity, and the main factors that affect the sensitivity are ­­­­____. 
选项：