可調式光纖光柵濾波器

Abstract

在本篇論文中，我們使用相位光罩的方法研製光纖光柵。我們能穩定地製作出高反射率 (>99%)、低損耗、固定週期（頻寬 0.6nm）和漸變週期（頻寬 4nm）之光纖光柵。我們也成功的製作了光纖壓拉器，利用壓和拉的應變 (compressive and tensile strain) 來調變布拉格中心波長，使它形成一個可調式光纖光柵濾波器，當施加壓應變時，波長可調短 16nm，拉應變時，波長可調長 3.5nm。我們也定性的探討了雙折射 (birefringent) 效應對反射、穿透頻譜在應變作用下，形成兩個峰形狀的原因。最後我們將兩段可調式光纖光柵配合一段摻餌 (Er-doped) 光纖形成一個共振腔，製作了可調式 DBR 光纖雷射，初步嘗試時波長可調 3.7nm。

In this thesis we apply phase masks and hydrogen loading techniques in fabricating optical fiber gratings. High reflectivity (>99%) gratings are reproducibly made with bandwidths of 0.6 and 4 nm for a constant period and chirped period gratings, respectively. We also make two designs of mechanical adjusters with micrometer knobs to exert the compression and tensile stress in these gratings, which then become the tunable narrowband reflection filters. At compressive strain, the Bragg wavelength is blue-tunable to a maximum value of 16 nm and at tensile strain, it is redtunable by 3.5 nm. We discuss the effect of fiber birefringence under tensile strain for these gratings. Birefringence explains the appearance of the double-peak feature in the measured transmission and reflection spectra. By incorporating two tunable gratings and an Er-doped fiber, we demonstrate wavelength tunable DBR fiber lasers. A 3.7-nm tuning range is achieved in the preliminary test.