This paper presents a comparative spectral analysis for tuning all-fiber directional coupler-based Mach–Zehnder Interferometer (MZI) and all-fiber inline Micro Mach–Zehnder Interferometer (MMZI) configurations. The analytical background is necessary to estimate the change in the differential path length for tuning the channel (peak) wavelengths and inter-channel spacing (i.e. free spectral range) of the MZI. We briefly describe the method used to adjust the spectral response experimentally. The spectral tuning of all-fiber MZI and MMZI has been successfully implemented in different applications of fiber optic communication and sensing (Ramachandran et al (2014 IEEE Sens. J. 15 1270–4; 2017 Opt. Fiber Technol. 36 195–8), Kumar and Ramachandran (2013 Opt. Commun. 289 92–96; 2014 Opt. Laser Technol. 63 144–7)). The spectral tuning of the MMZI is based on the interference length. Compared to MZI, miniaturized MMZI does not deal with any spectral fluctuation when employed in dense wavelength division multiplexing (DWDM) application and a sensing scheme. Research during the past year has surveyed the different MZI structures from an application perspective to infer that MMZI might be the most suitable configuration for sensing applications, and MZI may prove to be more useful in DWDM optical networks.

本文介绍了用于调谐基于全光纤定向耦合器的 Mach-Zehnder 干涉仪 (MZI) 和全光纤在线微 Mach-Zehnder 干涉仪 (MMZI) 配置的比较光谱分析。分析背景对于估计用于调谐 MZI 的通道（峰值）波长和通道间间距（即自由光谱范围）的差分路径长度的变化是必要的。我们简要描述了用于通过实验调整光谱响应的方法。全光纤 MZI 和 MMZI 的光谱调谐已在光纤通信和传感的不同应用中成功实现（Ramachandran等人（2014 IEEE Sens. J. 15 1270–4；2017 Opt. Fiber Technol. 36）195-8)、Kumar 和 Ramachandran（2013 Opt. Commun. 289 92-96；2014 Opt. Laser Technol. 63 144-7)）。MMZI 的频谱调谐基于干扰长度。与 MZI 相比，小型化 MMZI 在用于密集波分复用 (DWDM) 应用和传感方案时不会处理任何光谱波动。过去一年的研究从应用的角度调查了不同的 MZI 结构，推断 MMZI 可能是最适合传感应用的配置，并且 MZI 可能被证明在 DWDM 光网络中更有用。