兆赫波段可調式液態晶體Solc濾波器

Abstract

我們研製了一種兆赫波段可調式Solc 濾波器，實驗數據與理論預測相符合。利用外加磁場控制向列型液晶(E7)的雙折射性，可在室溫下連續調變穿透頻率從0.176至0.793 THz (中心頻率之調幅可達350%)；此濾波器之置入能量損耗為5dB。為了改善置入能量損失、使用便利性與快速反應等因素，我們也設計了一種電場控制向列型液晶(E7)之Solc濾波器，在室溫下連續可調範圍從0.717到1.142 THz (中心頻率之調幅可達59%)。我們也量測具較大雙折射性(□n~0.18)向列型液晶 (DN125262W) 的折射係數並利用此材料製作Solc 濾波器，與E7相同濾波效果下，此濾波器操作在較低頻區(< 0.7 THz)，置入性損耗減少~1.5 dB。

A large tunable range, room-temperature terahertz Solc filter has been demonstrated. The first central pass-band frequency of the device can be continuously tuned from 0.176 to 0.793 THz (a fractional tuning range of 350%) using magnetically controlled birefringence in the nematic liquid crystals (E7). The insertion loss of the present device is about 5 dB. We also designed and constructed an electrically controlled, tunable terahertz Solc filter of which the central pass-band frequency can be continuously tuned from 0.717 to 1.142 THz (a fractional tuning range of 59%). The electrically tuned filter has advantages of compact use, ease in control, fast response, and low insertion loss. Moreover, we have investigated a commercial liquid crystal DN125262W with large birefringence and applied it for filtering applications. It can operate at low frequencies (< 0.7 THz).and the insertion loss reduce ~1.5dB, comparing with E7. The results are in good agreement with theoretic predictions.