A Study Of Terahertz Photonic Crystal Wavelength Division Multiplexer Based On Graphene

Photonic crystals have attracted more attentions for the forbidden band properties. For example, two-dimensional photonic crystal with line defects can control the electromagnetic wave. Photonic crystals have become one of the hotspot of the electromagnetic device research. Traditional photonic crystal WDM has a fast transfer rate, low loss and high stability, but it cannot get rid of low bandwidth and bad dynamic adjustability. To solve the problem of adjustability, this paper introduces graphene, which has been reported that graphene can support SPP wave at THz and its equivalent refractive index can be regulated by the bias voltage. If the desired 2D PC patterns can be created on graphene platform, when applied to design the THz WDM, it will greatly improve the device performance, which means a wide and adjustable bandwidth. In addition, it enriches the designable characteristic of the photonic crystal. The two-dimensional photonic crystal which can be electrically controlled, has a well application prospect in terahertz devices. Therefore, this paper mainly study the graphene-based THz photonic crystal wavelength division multiplexer, the bandwidth of which can be electrically tunable. The main works are as follows:Firstly, this paper studies the graphene photonic crystal band gap and defect mode. Then we get the graphene photonic crystal waveguide dispersion curve and the working frequency band. A kind of high-performance of three wavelength WDM is proposed and designed. The center frequence of WDM respectively is at 8.2 THz,8.6 THz and 9.3THz. The transmission rate is better than 80%, isolation better than 15 dB and the bandwidth is up to 0.52 THz.Secondly, this paper studies the impact for the graphene photonic crystal WDM when the graphene chemical potential changes. Through simulation analysis, under unchanging the structure, the working frequency band of the designed graphene photonic crystal WDM is electrically tunable. The same output port can even have two working frequency band, which can effectively improve the WDM utilization.Finally, in order to realize narrowband control for the output signal of the wideband WDM, a kind of narrow-band waveguide-microcavity-waveguide filter is presented, which can be electrically controlled. By controlling the chemical potential of grapheme structure in the corresponding position, it can effectively change the filter characteristics and show a good narrow-band filter property.