Nair Anitha S, Sudeep Kumar V P, Joe Hubert
Appl Opt. 2015 Mar 10;54(8):2007-10. doi: 10.1364/AO.54.002007.
A record tunability of 35 nm for the LP(11) cladding-mode resonance in a twisted mechanically induced long-period fiber grating using standard single-mode communication fiber is demonstrated. By forming the LP(11) resonance far away from its cut-off wavelength and modifying the grooves of the grating in the form of smooth semicircular humps, a high twist sensitivity of 8.75 nm/(rad/cm) and a controlled tunability of 35 nm is achieved. The fiber with its lacquer coating is not broken even at a severe twist rate of 5.44 rad/cm. The present design can be used as a novel variable optical selective wavelength attenuator since the bandwidth, rejection efficiency, and center wavelength can be controlled by changing the grating length, pressure over the grating, and fiber twist, respectively. Using the results, a cost-effective tunable variable optical attenuator for selective channel-blanking applications is also demonstrated. A fine tunability of 1.5 nm is achieved for a twist rate change of 0.1 rad/cm.
在使用标准单模通信光纤的扭曲机械诱导长周期光纤光栅中，展示了LP(11)包层模共振35 nm的创纪录可调谐性。通过使LP(11)共振远离其截止波长，并以光滑半圆形凸起的形式修改光栅的凹槽，实现了8.75 nm/(rad/cm)的高扭曲灵敏度和35 nm的可控可调谐性。即使在5.44 rad/cm的严重扭曲率下，带有漆层的光纤也不会断裂。由于带宽、抑制效率和中心波长可以分别通过改变光栅长度、光栅上的压力和光纤扭曲来控制，目前的设计可以用作新型可变光学选择性波长衰减器。利用这些结果，还展示了一种用于选择性通道消隐应用的经济高效的可调谐可变光学衰减器。对于0.1 rad/cm的扭曲率变化，实现了1.5 nm的精细可调谐性。
