Executive Summary : | In fibre optic communication the data transmitted as the pulses of light in the Single Mode fibre (SMF). The SMF uses the technology of Wavelength Division Multiplexing (WDM) to send multiple channels in a single medium, increasing the efficiency of the medium. The WDM is classified as Coarse Wavelength Division Multiplexing (CWDM) and Dense Wavelength Division Multiplexing (DWDM).The CWDM used for short range communication, able to transmit the 18 channels with the channel spacing of 20 nm. The DWDM technique supports 80 channels with different centre wavelengths through SMF, the channel spacing between each wavelength around 0.8 nm/0.4 nm/0.2 nm/0.1 nm. The demultiplexer is the prominent device in the communication systems. It will separate the unique frequency to individual users. The bandwidth of each user is decided based on the CWDM or DWDM technology. Based on the technology, utilization of the spectrum efficiency will be determined. The DWDM technology efficiently accommodates more users with narrow spectral line width. The proposed demultiplexer uses the new idea of using Photonic Crystal for the principle of separating the multiple wavelengths from the SMF to single wavelength to the unique user. The photonic crystals are artificially made microstructure material with a spatially periodic distribution of dielectric constant. The novel property in PC is Photonic Band Gap (PBG), also called Stop band. The PBG does not allow the photons to pass through the gap; the density of photons in PBG is zero. Through introducing the defects or changing the structural parameter of the crystal it is possible to allow the photon to pass through the PBG. The proposed device used the principle to separate the multiple wavelengths into the single wavelength for the end user. The proposed demultiplexer is able to drop two different spectral line widths to support different networks in real time applications. The design to drop 0.8 nm and 0.4 nm from the single design, this idea is useful and flexible for real time systems to support different network users. The second idea is a single ring resonator able to drop two wavelengths with different DWDM spectral linewidth.The proposed integrated model reduced the device size drastically. The proposed integrated demultiplexer reduces the network cost significantly. The concepts applied in future DWDM systems |