The Research On Characteristics Of Two-wavelength Terahertz Modulator Based On Compound Lattice Photonic Crystals

The THz communication has broad application prospects in the future high-speed and ultra-wideband wireless communications. THz modulator is an important device in the THz wave communication,Combining photonic crystal and the THz wave these two technologies can play a special capacity of local light for the photonic crystal, and can also take advantage of the convenience of the device fabrication process in the THz range.With the increasingly widespread of multi-wavelength communication systems, study of the multi-wavelength modulator is also very necessary.The modulation principles of photonic crystal terahertz modulator are firstly described in this paper, and then two different structures of Compound Lattice photonic crystal two-wavelength THz modulators are presented. These two modulators are based on two-dimensional photonic crystal of compound lattice, then introduce one point defect and line defects, and make themselves became optical controlled THz modulator by introducing optical controlled GaAs as a tunanble material in the point defects. Because of the compound lattice of photonic crystal, there are two different defect modes for the point defect, so it can modulate two different THz waves by only a point defect. The difference of the two modulators is the different combination of point defect and line defects; The insertion loss, extinction ratio, modulation rate and other properties of these two modulators are analyzed when the incident waves are single wavelength or two wavelengths When the two-wavelength incident at the same time, for the direct coupling structure of THz modulator,the insertion loss is 0.42dB, the extinction ratio is 61dB, the maximum modulation rate up to 1.5Gbit/s, and for the side coupling structure of THz modulator, the insertion loss is 0.16dB, the extinction ratio is 34.9dB, the maximum modulation rate 6.76Gbit/s. Then the affect of the performance for the direct coupling structure of THz modulator is analyzed, while the dislocation, radius and shape of the point defect change.These are benefit for the actual production of photonic crystal modulatior and the corresponding error analysis. In the end, based on the features of the THz wave modulator of compound lattice PC, its applications and prospects in future THz wireless communication systems are briefly discussed.