Error estimation in the analytical modeling of abrupt taper Mach-Zehnder interferometers

Abstract

In-line fiber interferometers based on abrupt tapers have been shown as a promising low-cost platform for various sensing applications. Many variations have been demonstrated experimentally using combinations and permutations of novel photonic devices such as photonic crystal fibers or multimode fibers. In this manuscript, an analytical model for light propagation in an abrupt taper Mach-Zehnder Interferometer in commercial single-mode fiber based on coupled-mode theory is detailed. The model calculates the mode propagation process, and the result is compared with previous numerical simulations. For experimental verification, an in-line Mach-Zehnder interferometer based on an abruptly tapered fiber is fabricated and tested. The spectrum calculated by the model matches well with the measured spectrum. To reduce the computational complexity, a method for step size estimation and the corresponding error accumulation is discussed and verified. This can serve as a basis to estimate the optical responses of this class of abrupt taper based fiber sensors. With the right packaging, these sensors can play a vital role in rugged and hostile environments.

Tension and Torsion Sensing With a Double-Taper Mach-Zehnder Interferometer

“…The first taper is initially excited with LP 01 , and at the output, it excites HOMs with LP 05 mode as the most prior in power [9]. The refractive index of the epoxy layer is assumed to be 1.467, which causes the ERI of the coupled modes to attain an imaginary part leading to the HOMs dissipation and change in priority order.…”

“…Amongst all, the latter in the form of a Double-Taper Mach-Zehnder Interferometer (DTMZI) shows more promise as it can be fabricated quickly with the essential tools in hand, namely single-mode fiber (SMF) and fusion splicer [8]. Moreover, abrupt taper's modeling and its fabrication imperfections have been thoroughly investigated via recent works [9]- [11]. The application of measuring axial strain has been studied on DTMZI, and their modal behaviour has been thoroughly studied [12], [13].…”

Spectral Modal Decomposition of Abrupt Fiber Tapers Based on Simulated Annealing Method

“…According to Eq. (5) and (6), the coupling process depends upon the inverse Effective Refractive Index (ERI) difference between the coupling modes [21]:…”