SENSITIVITY VARIATION RESEARCH OF TILTED FIBER BRAGG GRATING DURING CHEMICAL ETCHING

Subject of Research. The paper presents experimental results of the chemical etching duration impact on the tilted fiber Bragg grating transmission spectrum. The goal of this research is the sensitivity growth of the tilted fiber Bragg grating aimed at its application as an element of fiber optical sensor for refractive index of liquids measurements. Method. The chemical etching was performed in the 50 % hydrofluoric acid solution. The chemical etching duration was 5, 10, 15, 20 and 30 minutes with pauses for spectra measurements. The spectrum of the tilted fiber Bragg grating was measured at every research step in the media with various refractive index. Main Results. The sensitivity estimation of the tilted fiber Bragg grating to the variation of refractive index is performed. The decrease of the optic fiber thickness as a result of chemical etching leads to lower responsivity of the sensor. Practical Relevance. Experimental research shows that chemical etching decreases the sensitivity of tilted fiber Bragg grating to the refractive index variation for the medium under study. Analysis of measurement results is applicable in the design and development of concentration optic fiber sensors or solution refractive index of the researched material.