Departament de Física Aplicada i electromagnetisme and Institut Universitari de Ciència dels Materials, Universitat de València, Carrer Dr. Moliner 50, Burjassot E-46100, Spain. d.saez‑
Opt Lett. 2012 Oct 15;37(20):4314-6. doi: 10.1364/OL.37.004314.
In-fiber mode engineering based on the combination of Bragg and long-period gratings (LPGs) permits the implementation of noninterferometric transmission filters with narrow passbands using standard single-mode fiber. The design of the bandpass filter is based on the coupling between propagating and counterpropagating cladding modes in two fiber Bragg gratings. A LPG located between the Bragg gratings transfers power from the input fundamental mode to a specific cladding mode and recouples the filtered signal to the output fundamental mode. The filter produces a series of narrow passbands of about 30 pm linewidth with a maximum transmittance above 60%, 20 dB isolation, and passband separation of about 1 nm, each corresponding to the contribution of a different cladding mode.
基于布拉格光纤光栅（FBG）和长周期光纤光栅（LPG）组合的光纤模式工程，允许使用标准单模光纤实现具有窄带通的非干涉传输滤波器。带通滤波器的设计基于两个光纤布拉格光栅中传播和反向传播包层模式之间的耦合。位于布拉格光栅之间的 LPG 将功率从输入基模传输到特定的包层模，并将滤波后的信号重新耦合到输出基模。该滤波器产生一系列约 30 pm 线宽的窄带通，最大透过率超过 60%，隔离度 20 dB，通带分离约 1nm，每个通带对应于不同包层模的贡献。
