激光与光电子学进展, 2020, 57 (19): 190605, 网络出版: 2020-09-27
基于高精度微锥型长周期光纤光栅的宽带滤波器 下载: 982次
Broadband Filter Based on High-Precision Microtapered Long-Period Fiber Gratings
光纤光学 长周期光纤光栅 二氧化碳激光加热 光纤微加工 宽带滤波 fiber optics long-period fiber gratings carbon dioxide laser heating fiber micro processing broadband filtering
摘要
提出基于双光束二氧化碳(CO2)激光的加热方法,设计并搭建了微锥型结构的长周期光纤光栅制备系统。该系统通过精确控制CO2激光功率、加热时间、光斑大小等实现均匀加热和光纤软化,通过高精度的步进电机控制光纤微型拉锥长度和拉锥比,以产生周期性的物理形变,制备出高精度(消光比>30 dB,插入损耗<1 dB)、光谱不退化的微锥型长周期光纤光栅(MT-LPFGs)。基于级联MT-LPFGs实现了宽带全光纤滤波器。实验结果表明,设计的双级联MT-LPFGs在30 dB消光比下实现了15 nm的宽带滤波,与单个光栅相比,其滤波带宽增加7.5倍;三级联MT-LPFGs在-25 dB带阻深度下能够实现25.2 nm的宽带滤波,该滤波带宽为单个光栅的12.6倍。最后,通过弯曲实验证明了级联光栅滤波器的弯曲容限为1.183 m -1。该滤波器具有精度高、制备简单、光谱不退化等优点,在宽带滤波方面有着重要应用。
Abstract
A heating method based on double-beam carbon dioxide (CO2) laser is proposed, and the fabrication system of a long-period fiber grating with a microtapered structure is designed and built. The system achieves uniform heating and fiber softening by accurately controlling the CO2 laser power, heating time, and spot size. The microtapered long-period fiber gratings (MT-LPFGs) with high-precision (extinction ratio >30 dB and insertion loss <1 dB) and without spectral degradation are fabricated by controlling the micro taper length and tapering ratio via a high-precision stepping motor. Based on cascaded MT-LPFGs, a broadband all fiber filter is realized. Experimental results show that the designed dual cascaded MT-LPFGs can achieve 15 nm broadband filtering at the extinction ratio of 30 dB, and the filtering bandwidth is increased by 7.5 times compared with that of the single grating. The three cascaded MT-LDFGs can achieve 25.2 nm broadband filtering at -25 dB band stop depth, which is 12.6 times that of a single grating. Finally, the bending tolerance of the cascaded grating filter is proved to be 1.183 m -1 by the bending experiment. The filter has advantages of high precision, simple preparation, and no spectral degradation, so it has an important application in broadband filtering.
严学文, 任立勇, 杨利, 冉东升, 韩冬冬, 王勇凯, 梁磊, 许程访, 刘继红, 董军, 任凯利. 基于高精度微锥型长周期光纤光栅的宽带滤波器[J]. 激光与光电子学进展, 2020, 57(19): 190605. Xuewen Yan, Liyong Ren, Li Yang, Dongsheng Ran, Dongdong Han, Yongkai Wang, Lei Liang, Chengfang Xu, Jihong Liu, Jun Dong, Kaili Ren. Broadband Filter Based on High-Precision Microtapered Long-Period Fiber Gratings[J]. Laser & Optoelectronics Progress, 2020, 57(19): 190605.