Since the discovery of semiconductor-optical fiber, the development of optical communication has been significant. In particular, a baseband modulation frequency in high-speed communication has been increased up to the order of 10 GHz at the research level and of 1 GHz at the practical level. A factor which is the obstacle for further improvement is the bandpass width limitation for a transmitted signal caused by the spread of an oscillation spectrum of LD and also the wavelength dispersion of an optical fiber. For longdistance and high-speed transmission, it is important to determine accurately the spread of the LD spectrum for designing an optical transmission system.The objective of the present study is to clarify the condition required for a high-resolution optical spectrum analysis system, which is essential for understanding the spectrum-spread and chirping of the LD laser at a time of high-speed modulation. A comparison of various measurement systems is made. A method of combining the diffraction grating system and the Fabry-Perot etalon system is proposed, and the optimization of the system is discussed in detail.The present paper describes for the first time the optimization of the tandem configuration of a diffraction grating and Fabry-Perot etalon systems. Based on those discussions, a prototype system has been constructed with which a maximum wavelength sweeping width of 200 MHz/div and resolution of 100 MHz were demonstrated.
Because of the progress in optical communicationtechnology, understanding the propagation characteristic of optical fibers has become very important. In particular, since optical networks have been used widely, the evaluation of optical fibers in the field is essential. This paper describes the measurement of the chromatic dispersion of optical fibers and a system suitable for the measurement in the field. The approach is based on the baseband phase-comparison method. First, the conditions required for this measurement system will beclarified. Then the measurement of wavelengths and wavelength separation satisfying the requirements will be obtained by simulation. The source of each wavelength must be modulated.However, to increase the fiber length and to improve measurement precision, a modulation method based on multiple sinusoidal waves will be proposed, and the upper and lower limit of the optimum modulation frequency will be clarified. The measurement system will be constructed from these results. The technical problems in realizing the system will be shown.Finally, an example of data measured by the constructed system will be shown, and it will be demonstrated that a resolution of 0.01 pslnmkm and measurement precision of * 0.3 ps/nm/km can be achieved at wavelengths of 1.3 and 1.55 pm.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.