Chapters authored
Selective Mode Excitation: A Technique for Advanced Fiber Systems
Actual problems arising in development of fiber optical systems are increasing the information capacity and enhancing data security. Different encoding methods and data compression techniques have been developed to meet these requirements. The presented materials emphasize advantages of application of selective mode excitation in fiber systems that lead to both increasing the system information capacity and enhancing data security. Three‐stage hierarchical scheme of data compression [where time division multiplexing (TDM) method is the content of the first stage, the second stage utilizes wavelength division multiplexing, and mode division multiplexing (MDM) is applied at the last stage] is discussed. Furthermore, it is highlighted that selective mode excitation is able to embarrass eavesdropping. It is shown that just application of the mentioned technique allows enhancing data security, while designing of special system architectures provides additional increase of data protection level. The examples of such system schemes are presented. Thus, application of selective mode excitation could improve the performances of fiber systems significantly, at least the ones such as short‐ and middle‐haul communication lines and local area networks (LANs).
Part of the book: Optical Fiber and Wireless Communications
End-Fire Mode Spectroscopy: A Measuring Technique for Optical Waveguides
End-fire mode spectroscopy technique provides reliable measurement of the whole mode spectrum of optical waveguides having arbitrary cross refractive index profile. The method is based on registration of light beams radiated from the abrupt output edge of the waveguide, with each beam corresponding to the individual waveguide mode. Due to different values of mode propagation constants, modes of different orders demonstrate different refraction angles at the output waveguide face when modes reach that face under the same nonzero inclination angle. Just this feature is used in the technique. Mode excitation is performed directly through the input waveguide face, and therefore the technique can be applied to analyze mode spectrum of arbitrary waveguides, including the ones with non-monotonic index profiles (particularly, symmetric step-index profiles or buried graded-index waveguides with any burying depths).
Part of the book: Emerging Waveguide Technology