Single-mode fiber refractive index sensor with large lateral offset fusion splicing between two abrupt tapers

Abstract

Abstract. We propose a novel refractive index (RI) sensor based on a fiber Mach-Zehnder interferometer formed by large lateral offset fusion splicing between two abrupt tapers. The cladding modes are efficiently excited by transmitted light in the large misalignment junctions. The RI sensitivity of the sensor to surrounding RI change is measured, and the sensitivity of 100 nm∕RIU is obtained, which is three to six times higher than that of fiber structures with only a pair of tapers or two offset junctions. Moreover, the sensor is made by a lowcost fabrication method. Thus, the proposed structure is beneficial to the RI sensing applications.

Theoretical study of the dispersion effects occurring at optical fiber connections

“…At the same time, published sources [5][6][7][8][9][10] do not provide information on the effect of the investigated power redistribution processes on form, and, consequently, duration of the optical signal.…”

“…A considerable number of scientific studies are devoted to studies in the field of signal attenuation at OF connection points. Specifically, models of signal energy distribution in detachable [5] and permanent OF connections were synthesized [6,7]. However, no consideration of the effect of signal form change in the points of fiber connection was provided in these studies.…”

“…These studies also do not take into consideration a phenomenon of signal form distortion caused by redistribution of signal power in an OF connection point. An extensive list of references devoted to the mentioned issues is given in [5][6][7][8][9][10]. However, these studies do not consider the effect of fiber connection points on the optical signal length and magnitude of introduced dispersion.…”

“…N (1 -qN ) for different values of the number of connections N: at N=1000 (1); at N=100 (2); at N=10 (3) The formulas for the effective pulse duration (18) and the increment of CPD (19) were obtained with some simplifications. Direct numerical modeling of the operator (7) requires explicit specification of the initial form of optical signals and model parameters.…”

“…In the second case, the plan of distribution of face-to-face lengths is constructed in a reverse order: the first face-to-face length is approximately 3.5 km and then the face-to-face lengths are reduced by about 30.3 m. In both cases, total number of face-to-face lengths is 100 and the total length of the regeneration line is 200 km as in the preceding calculations. The results of modeling the operator (7) for the Gaussian pulse with the previously defined parameters and probability p=10 -2 for two plans of distribution of face-to-face lengths from Fig. 10 are given in Fig.…”