Sophia Magazine vol.1 / SUMMER 2015

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11increase the number of bits transmitted per second. How-ever, there is a limit to the transmission capacity that can be achieved by simply sending ON and OFF signals that correspond to the ones and zeros of digital signals, which is about 10 gigabits per second. That is why we took an inter-est in wavelength-division multiplexing, which can simulta-neously transmit light of different wavelengths via a single optical ber cable.” The dispersive element achieves the function of dividing light at the receiver in WDM systems. Light is usually di-vided into multiple wavelengths using interference fringes with a diffraction grating, which functions in the same way as a prism. Professor Takahashi realized this technology using a single 2-by-3 square centimeter integrated circuit CHRONICLESOF RESEARCHERS IN SOPHIA HIROSHITAKAHASHIProfessorDepartment of Information and Communication Sciences,Faculty of Scienceand Technology#01Schematic diagram of Arrayed-Waveguide Grating (AWG)-basedwavelength lters