Long-period D-fiber grating based robust and efficient bidirectional coupler for whispering gallery mode excitation
Long-period D-fiber grating based robust and efficient bidirectional coupler for whispering gallery mode excitation
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基于长周期 D 光纤光栅的稳健高效双向耦合器，用于回音壁模式激励
DOI：
10.1364/oe.479223
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发表时间：
2023
期刊：
影响因子：
3.8
通讯作者：
Tao Zhu
中科院分区：
文献类型：
--
作者：
Jing Chai;Leilei Shi;Nan Guo;Liyang Jin;Jiali Li;Miaoxin Bai;Da Wei;Wei Huang;Min Liu;Tao Zhu
从理论和实验上证明了一种基于D型光纤长周期光栅（LPG）的回音壁模（WGM）双向耦合器。LPG根据相位匹配条件将基芯模耦合到前向传播的包层模，不仅增强了光纤的倏逝场，而且在感兴趣的波长带中选择性地激发WGM。实验结果表明，在最大抛光深度为56 μm的侧面抛光D型光纤中，采用电弧放电法制备出节距为680 μm的长周期光纤（LPG），在直径为242 μm的LPG耦合球形石英WGM谐振器中，可以获得高达10.5 dB的最大谐振对比度和104量级的品质因子（Q因子）。除了高鲁棒性和效率之外，这种基于LPG的WGM耦合器还表现出双向性，即，它与入射光的入射方向无关，这为基于WGM谐振腔的实际应用提供了可靠和灵活的光纤耦合器。
A robust and efficient bidirectional coupler for whispering gallery mode (WGM) excitation based on a long-period grating (LPG) inscribed in D-fiber is theoretically and experimentally demonstrated. The LPG coupling the fundamental core mode to the forward propagating cladding modes according to the phase-matching condition not only enhances the evanescent field of the fiber but also selectively excites the WGM in a wavelength band of interest. Experimental results show that a maximum resonance contrast as high as 10.5 dB and a quality factor (Q-factor) on the order of 104 can be achieved in an LPG coupled spherical silica WGM resonator with a diameter of 242 µm, where the LPG with a pitch of 680 µm is fabricated by arc-discharging in a side-polished D-fiber with a maximum polishing depth of 56 µm. In addition to high robustness and efficiency, such an LPG-based WGM coupler also demonstrates bidirectionality, i.e., it is independent of the injection direction of the input light, which provides a reliable and flexible fiber coupler for the WGM resonator based practical applications.