Characterization Of The Faraday Anomalous Dispersion Optical Filter Based On The Hollow Cathode Lamp

Faraday anomalous dispersion optical filter(FADOF)is an atomic filter based on the anomalous dispersion effect occurring under the external magnetic field conditions,which has the advantages of high transmittance,ultra-narrow bandwidth,large field of view and high noise suppression,and can greatly meet the filtering needs in various scenarios.Conventional FADOF usually heating the atomic vapor cell to obtain atomic vapor,which has several limitations,such as cannot work at room temperature and being sensitive to ambient temperature;In addition to the above limitations,an additional pump laser is required to prepare the excited state saturated vapor for the excited state(ES)FADOF,which greatly complicates the implementation of the ES-FADOF.1.Completed the construction and research of a ground state Faraday anomalous dispersion filter based on the hollow cathode lamp.A hollow cathode lamp(HCL)is used instead of the atomic vapor cell(VC)to address the limitations of the VC-FADOF,which is able to obtain enough atomic vapor for establish the filtering due to its special"sputtering"method.The ground state FADOF with an operating wavelength of 780 nm,constructed using a rubidium hollow cathode lamp,is able to operate normally at room temperature,and the peak transmittance can reach 29%at a current of 18 mA and a magnetic field of 260 G.The transmission spectrum of the VC-FADOF was calculated using the ElecSus,and a crosssectional comparison between the HCL-FADOF and the VC-FADOF was performed.2.The Thermal and temporal characteristics of Faraday anomalous dispersion optical filters based on a hollow cathode lamp were investigated.A semi-conductor cooler is added to the established ground-state HCL-FADOF to simulate the change of the ambient temperature to achieve the adjustment of the HCL temperature.The HCLFADOF can work stably at an ambient temperature of-5℃,and can maintains a great stability when the ambient temperature changes by 25℃(-5℃ to 20℃).The temporal characteristics of the HCL-FADOF were measured for the warm-up time of the HCL,and a side-by-side comparison with the temporal characteristics of the VC-FADOF was performed.3.The construction and research of an excited state Faraday anomalous dispersion optical filter based on the hollow cathode lamp was completed.Considering the collisions between the high kinetic energy particles inside HCL and the atoms of cathode materials,a part of atoms can be excited,thus it can enable the preparation of excited state atomic vapor.An ES-FADOF with an operating wavelength of 1529 nm was constructed by using a rubidium hollow cathode lamp,and its characteristics were investigated in detail.The ES-FADOF constructed in this experiment has the feature of heating-free and pump-free,and the use of HCL greatly simplifies the structure of ES-FADOF and reduces the implementation difficulty.The peak transmittance can reach 1.5%at a current of 20 mA and a magnetic field of 214 G.Since 1529 nm is in the communication band,the performance of the filter is measured using the quality factor FOM.