Preparation And Performance Test Of Ni-nanowire-array THz Control Device

Terahertz(THz)wave has become a hot spot for research and development in various countries due to its unique electromagnetic characteristics.However,the lack of efficient and cheap THz functional devices has limited the further development of THz technology.Due to the good optical anisotropy of one-dimensional nanomaterials,THz control devices based on one-dimensional nanomaterial arrays have been extensively studied and achieved some results in recent years.However,they still face some difficulties and challenges in terms of large-scale preparation and performance.Due to the good magnetic properties,Ni nanowires can be accurately controlled by an external magnetic field in a solvent to prepare a large-area,ordered nanowire arrays with controllable thickness.Therefore,Ni nanowires have great potential in the application of THz control devices.In this paper,Ni nanowires were synthesized by chemical reduction method.The aligned Ni-nanowire arrays were prepared by using magnetic field assist in a solvent,and their properties were tested and analyzed.The main research results are as follows:(1)The Ni-nanowire arrays with different thicknesses have been preapred.The results showed that as the thickness of the array increases,the degree of polarization(DOP)and extinction ratio(ER)of the device also increase;(2)The polarization performance of the device is improved.The study found that the three-layer Ni-nanowire-array polarizer has a DOP of 99.9% and an ER of46.6 d B in the 0.3-2.3 THz spectral range,which is much higher than that of the single-layer Ni-nanowire arrays sample;(3)The stability of Ni-nanowire-array polarizer is proved.The polarizer still maintains good polarization performance after annealing at 250? for 1 h;(4)A composite structure of Ge film/Ni-nanowire arrays was prepared.The results showed that the composite structure has an ultra-fast light response speed,and its response time and recovery time are lower than 1.6 ps and 3 ps,respectively.This is similar to the performance of Ga As nanowire arrays and carbon nanotube arrays reported in the literature.