最新刊期
      卷 ， 期 1 ， 1989
      • Zhang Xu
        Issue 1, Pages: 1-11(1989) DOI: 10.13756/j.gtxyj.1989.01.001
        摘要：This paper reviews the advantages of the coherent optical fiber communication systems over the conventional systems. There are two kinds of detection schemes: heterodyne and homodyne detection, they provide higher receiver sensitivity than direct detection. On the other hand, there are two kinds of digital modulation schemes: FSK,CPFSK,and PSK.DPSK, their receiver sensitivity and linewidth requirements are dif- ferent from each other. Then the paper discusses the requirments to single frequency laser, including phase noise and linewidth.It shows that DFB structure is desirable. The dual-PIN balanced mixer used for heterodyne detection is mentioned. The progress of bitrate-distancc product of experimental system is discribed, up to now,the best records ars 400 Mb/s-290 km and 2 Gb/s-200km. Since the coherent optical fiber communication offers very close channel spacing, it allows densely packed FDM operation, theorectically up to 1000 channels of optical carriers. The use of phase diversity reception and polarization diversity reception to improve the system performance is briefly described. Finally the paper briefly mentions the possible application of the coherent fiber communication in local subscriber network. There are highly -coherent, medium-coherent and weakly-coherent systems, present applications are mostly of medium-coherent optical fiber communications, which will be widely used after the opto-electronic integration OEIC becomes successful.  
          
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      • Issue 1, Pages: 11(1989) DOI: 10.13756/j.gtxyj.1989.01.002
        摘要：<正> 在光纤传感技术中,单模保偏光纤有着广泛而诱人的应用前景,低损耗单模保偏光纤又是将来实现相干通信的基石。70年代末,以英国南安普顿大学为代表,国外许多单位竞相开展单模保偏光纤及其测试技术的研究,提出了熊猫（PANDA）型,蝴蝶结（Bow-tie）型和椭圆应力包层型多种结构的保偏光纤。近几年,鉴于研究光纤陀螺仪、大电流或强磁场等新型光纤传感器的需  
          
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      • Wang Duanxiang
        Issue 1, Pages: 12-22(1989) DOI: 10.13756/j.gtxyj.1989.01.003
        摘要：In this paper, the factors which limit the transmission speed of the fiber optic communication systems are discussed. The multi-access processes are discribed. The trends of the development of the high speed fiber communication systems are discussed.  
          
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      • Mao Qian
        Issue 1, Pages: 23-31(1989) DOI: 10.13756/j.gtxyj.1989.01.004
        摘要：In this paper, the first provincial 34 Mb/s long-distance fiber cable trunk line in China is described. Besides the cable installation, splicing and testing, some technical problems in these processes are also analysed and discussed.  
          
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      • Le Zhonggao
        Issue 1, Pages: 32-41(1989) DOI: 10.13756/j.gtxyj.1989.01.005
        摘要：In this paper, the nonlinear transfer function of LED driver in Color TV fiber transmission system is Provided. Its amplitude and phase are related with LED characteristic parameters from the manufacturer. Therefore, it is possible to analyze quantitatively DP and DG, the nonlinear distortion of LED driver.  
          
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      • Yang Guishen Wang Yuzhang Dong Zhijiang Huang Kaiping
        Issue 1, Pages: 42-47(1989) DOI: 10.13756/j.gtxyj.1989.01.006
        摘要：This paper introduces and discusses the lifetime,hard screening and high-low temperature cycling test of 1.3μm InGaAsP DC-PBH lasers. Results are MTTF up to 4000 hrs at 50℃, which could be expected to exceed 105 hrs （when Ea is 0.9 eV） at the room temperature （20℃）. The observed modes of the lifetime are in good agreement with log-normal distributions.  
          
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      • Zhu Jiaxing Liang Puyi
        Issue 1, Pages: 48-58(1989) DOI: 10.13756/j.gtxyj.1989.01.007
        摘要：This paper gives a brief description for the application of CRC in the primary PCM multiplexing equipment. Discussions are focused on the coding method of cyclic code, the concret situation of CRC in the first bit of a frame, the frame location of CRC and the monitoring of bit-error and mode. In the end, the detailed realizable scheme for CRC-4 and the results of the computer simulation are briefly demonstrated.  
          
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      • Zou Linsen Lei Daoyu
        Issue 1, Pages: 59-63(1989) DOI: 10.13756/j.gtxyj.1989.01.008
        摘要：Fluorine has become an important dopant in MCVD method, which is used to make a variety of single-mode optical fibers with inner cladding refractive index depression. Experiment shows that the refractive index depression due to the dopping of CCl2F2 is proportional to the flow of CCL3F2. The deposition efficiency of SiO2 is corresponding to the optical flow of CCl2F2. When excessive flow of CCl2F2 is used, the formation of SiF4 will decrease the deposition efficiency of SiO2.Therefore, suitable flow of CCl2F2 will assit to increase the deposition rate and velocity of single-mode preforms and bring down the cost of the optical fibers.  
          
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