Xu Ou, Lu Shaohua, Feng Suchun, Jian Shuisheng
Institute of Lightwave Technology, Beijing Jiaotong University, Beijing, China.
J Opt Soc Am A Opt Image Sci Vis. 2009 Mar;26(3):639-49. doi: 10.1364/josaa.26.000639.
An all-fiber two-cavity Fabry-Perot (FP) configuration based on fiber Bragg gratings (FBGs) is proposed. The characteristics of transmission spectra for the two-cavity FP structure are theoretically analyzed and comprehensively modeled. The explicit expression of the transmission coefficient for the structures is derived. The general conditions for the lengths of two cavities and reflectivities of FBGs are presented to produce the single resonant transmission peak at the central wavelength in the FBG stop band. Based on the theoretical analysis, the transmission spectra of symmetric and asymmetric two-cavity FP structures are simulated, and the simulation results are discussed and explained qualitatively. The design guidelines of the device, including the choices of cavity lengths, grating lengths, and index modulation depths, are concluded. The results show that when the increasing of the cavity length of a single-cavity FP structure results in multiple resonant peaks in the stop band, the two-cavity FP structures of the same length can inhibit the secondary resonant peaks and keep the main peak without degrading the performance through appropriately designing the cavity lengths and FBGs. Finally, the fabrication error tolerances of the structures, including inaccurate cavity lengths and reflectivities of FBGs, are calculated and discussed.
提出了一种基于光纤布拉格光栅（FBG）的全光纤双腔法布里-珀罗（FP）结构。对双腔FP结构的透射光谱特性进行了理论分析和全面建模。推导了该结构透射系数的显式表达式。给出了两个腔的长度和FBG反射率的一般条件，以在FBG阻带的中心波长处产生单谐振透射峰。基于理论分析，对对称和非对称双腔FP结构的透射光谱进行了模拟，并对模拟结果进行了定性讨论和解释。总结了该器件的设计准则，包括腔长、光栅长度和折射率调制深度的选择。结果表明，当单腔FP结构的腔长增加导致阻带中出现多个谐振峰时，相同长度的双腔FP结构可以通过适当设计腔长和FBG来抑制二次谐振峰并保持主峰，而不会降低性能。最后，计算并讨论了该结构的制造误差容限，包括不准确的腔长和FBG反射率。
