Investigation on refractive index sensing characteristics based on multimode fiber specklegram

Abstract

In this study, the refractive index (RI) sensing characteristic of a single mode fiber (SMF)-multimode fiber (MMF) structure is investigated, and the two demodulation methods of specklegram and spectrum are compared experimentally. The results show that the RI resolution of the specklegram sensor is significantly higher than that of the optical spectrum analyzer (OSA). In addition, an SMF-no-core fiber (NCF)-MMF specklegram sensor is proposed. By extracting the eigenvalues of the gray-level co-occurrence matrix (GLCM) of the output specklegram, the eigenvalue of the angular second moment changes with the RI change, in which the addition of NCF increases the sensitivity from 0.25/RIU to 0.81/RIU. This specklegram sensor has good potential for high-resolution RI detection.

Advances in Optical Fiber Speckle Sensing: A Comprehensive Review

“…In recent years, significant attention has been paid to specklegram chemical-and biosensors involving various specialty fibers or standard fiber pre-processing, allowing light interaction with surrounding media. The applications of chemical sensors include salinity sensors [125,126], refractive index sensors [103,[127][128][129][130][131][132], biosensors [133], and even DNA-related sensors [134].…”

A Multimode Microfiber Specklegram Biosensor for Measurement of CEACAM5 through AI Diagnosis

“…Zhao et al analyzed in detail the responsiveness of a specklegram sensor based on single mode fiber-coreless fiber MMF structures for RI detection. The proposed method provides a good foundation for the subsequent application of specklegrams in biological sensing detection [17]. Besides, Li et al improved the resolution of pressure sensors to 0.001 MPa by combining a Fabry Perot interferometric cavity with optical fiber speckle patterns [18].…”

Fiber Speckle Sensing Scheme By Optical Power Filtering: Performance Analysis For Temperature Measurements

“…Different techniques have been reported to take advantage of the FSSs, from holographic to nonholographic techniques [18][19][20][21][22][23], some using correlation or amplitude analysis for the registered patterns by digital cameras [21,[24][25][26], while others utilize variations in light intensity or optical power within the speckle pattern [27][28][29][30]. In specific cases, FSS have demonstrated the same or superior resolution compared to spectral analysis [31,32].…”