Abstract: A diffraction device using a photonic crystal includes a diffraction grating, which has a period and periodically divides electromagnetic waves, and an input medium and an output medium, which contact the diffraction grating. The input medium is air, and the output medium is a one-dimensional layer having a periodic characteristic in a single direction (Z axis direction). The photonic crystal is formed by a periodic multilayer film having a period corresponding to the sum of the thickness of a first substance and the thickness of a second substance, which are superimposed. The diffraction device drastically decreases the resolution corresponding to the difference of the separated frequencies.

Abstract: An optical communication system is designed to suppress the generation of cross talk even in the case of small wavelength spacing and high bit-rate modulation. An Nth order harmonic generating device where N is an integer of 2 or larger is positioned before a demultiplexer to upconver the frequency or down convert the wavetlength of the light wave by N times. The frequency spacing between the carriers is increased and allows easier separation of the optical signal and permits denser WDM channels and/or higher data rate per channel. In addition, Si or GaAs based photodiodes may be used instead of InP based photodiodes since the 1550 nm bands are converted to 780 nm bands.

Abstract: An optical circuit is designed with demultiplexing and optical detection functionality with minimal crosstalk. An Nth order harmonic generation device is positioned before the demultiplexer to either convert the frequency or down convert the wavelength of the demultiplexed light wave by N-times. Upconverting the multiplexed signal at the receiver station is performed by either simultaneously upconverting N-times to create N times the original spacing between each optical channel or by upconverting the frequency of one optical channel at a time.

Abstract: An optical circuit is designed with demultiplexing and optical detection functionality with minimal crosstalk. An Nth order harmonic generation device is positioned before the demultiplexer to either convert the frequency or down convert the wavelength of the demultiplexed light wave by N-times. Upconverting the multiplexed signal at the receiver station is performed by either simultaneously upconverting N-times to create N times the original spacing between each optical channel or by upconverting the frequency of one optical channel at a time.

Abstract: An optical communication system is designed to suppress the generation of cross talk even in the case of small wavelength spacing and high bit-rate modulation. An Nth order harmonic generating device where N is an integer of 2 or larger is positioned before a demultiplexer to upconver the frequency or down convert the wavetlength of the light wave by N times. The frequency spacing between the carriers is increased and allows easier separation of the optical signal and permits denser WDM channels and/or higher data rate per channel. In addition, Si or GaAs based photodiodes may be used instead of InP based photodiodes since the 1550 nm bands are converted to 780 nm bands.