Abstract
An extrinsic Fabry-Perot interferometer (EFPI) composed of double fiber FP cavities in a glass capillary tube to generate Vernier effect has been fabricated and employed for gas pressure sensing. A lead-in single-mode fiber (LSMF) and a reflective single-mode fiber (RSMF) were inserted into the capillary tube to form a FP cavity. Femtosecond (fs) laser was used to ablate openings on a capillary tube for gas passage to the FP cavity. A fusion hole was also drilled on the end face of a SMF by fs laser. The sensitivity of the sensor is enhanced due to Vernier effect. Experimental results show that the sensitivity was as high as 86.64 nm/MPa in the range of 0~0.6 MPa, which is 32.8 times larger than that of an open-cavity EFPI sensor without Vernier effect. The temperature cross-sensitivity of the sensor was measured to be about 5.18 KPa/°C. The proposed sensor was characterized by its high sensitivity, compact structure and ease of fabrication, and would have extensive application prospects in gas sensing fields.
Highlights
Optic fiber sensors have been studied for few decades and attracted worldwide attention due to their advantages of immunity to electromagnetic, high temperature resistance, small size and light weight
Fabry-Perot interferometer (FPI) sensors are widely used in practical engineering applications owing to its simple principle, multiple manufacturing methods and convenience to combine with other fiber sensors [9,10,11]
An alternative method to obtain high sensitivity is a novel FPI sensors based on the Vernier effect, which is characterized with such qualities as low cost and being easy to implement [20,21,22,23,24]
Summary
Optic fiber sensors have been studied for few decades and attracted worldwide attention due to their advantages of immunity to electromagnetic, high temperature resistance, small size and light weight. Vernier caliper is a typical example of the Vernier effect used to improve the measurement accuracy It contains two independent structures with different sizes. The position of The the major peak is located at theiscommon resonant wavelength of wavelength of theFPIs. Vernier effect mainlyeffect intrinsic mainly intrinsic which the interference spectrumuntil not the available until sensors are finished which the interference spectrum not available sensors arethe finished [20,21,22,23,24]. Weifare surehas if the sensor effect has a Vernier effect or the factor amplification factorisofbig sensitivity is are in notfact sure thenot sensor a Vernier or the amplification of sensitivity enough to big enough improve the accuracy In this this paper, we developed a highly sensitive extrinsic Fabry-Perot interferometer interferometer (EFPI). Is a dozen times improved compared with EFPI gas pressure sensors without Vernier effect [27]
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