Strain and temperature sensing based on multimode interference in partially chlorinated polymer optical fibers

Abstract

Abstract:We develop strain and temperature sensors based on multimode interference in a partially chlorinated graded-index polymer optical fiber (PCGI-POF) and experimentally investigate their sensing performance at room temperature using incident light of ∼1300 nm wavelength. The length of the PCGI-POF was 0.7 m. The measured strain and temperature sensitivities were −4.47 pm/µε and +9.66 nm/°C/m, respectively, the absolute values of which were 0.29 times and over 350 times the values in a silica GI-MMF. This result suggests that the modal interference in PCGI-POFs is potentially applicable to high-sensitivity temperature measurement with low strain sensitivity.

Drastic sensitivity enhancement of temperature sensing based on multimodal interference in polymer optical fibers

“…Because spectral measurements with the widest possible span were preferable for this experiment, we employed an ultra-wideband source (Santec UWS-1000) that emits super-continuum light with an output spectrum from 1100 to 1760 nm (pumped at 1550 nm), instead of the wavelength-tunable laser used in previous reports. 23,26) The spectral power density of the source was higher than −30 dBm=nm over the full range; this value is much larger than that of a standard white-light source, which cannot be used in this case because of the high propagation loss of the PFGI-POF. The ultra-wideband source output was injected into the PFGI-POF, and the transmission spectrum was measured using an optical spectrum analyzer (OSA).…”

Observation of multimodal interference in millimeter-long polymer optical fibers

“…Sensing technology of strain and temperature using optical fibers has been an active area of research for many decades, and a wide variety of configurations have been developed thus far. They operate based on fiber Bragg gratings [1,2,3], long-period gratings [4,5], Brillouin scattering [6,7,8,9], Raman scattering [10,11], optical interference [12,13,14,15,16,17,18,19,20,21,22,23,24], and many others. Among numerous types of interference-based sensors, those based on intermodal interference in multimode fibers (MMFs) have recently attracted a considerable attention owing to their system simplicity and cost efficiency.…”

“…Of all the multimodal-interference-based sensors previously developed, which are well summarized in Table 1 in Ref. [12], the most widely used configuration is what is called a "single-mode-multimode-single-mode" (SMS) structure [13,14,15,16,17,18,19,20], in which two single-mode fibers (SMFs) sandwich an MMF.…”

“…However, the propagation loss of PMMA-based POFs at telecom wavelength is extremely high ()1 Â 10 5 dB/km). To tackle this issue, we have recently implemented SMS-based strain and temperature sensors using perfluorinated (PF) GI-POFs [16,17,18,19,20,21,22], which are the only POFs with a relatively low propagation loss even at telecom wavelength (∼250 dB/km at 1550 nm; ∼50 dB/km at 1300 nm). Using a PFGI-POF with a length of 1.0 m and a core diameter of 62.5 µm, we obtained a strain sensitivity of −111.8 pm/µε and a temperature sensitivity of +49.8 nm/°C at 1300 nm [16]; these large absolute values suggest that PFGI-POFbased SMS sensors are extremely sensitive to strain and temperature compared with other SMS sensors composed of silica MMFs or PMMA-POFs.…”

Thermal Memory Effect in Polymer Optical Fibers

“…To tackle this problem, strain and temperature sensors using polymer optical fibers (POFs) [11] have attracted a lot of attention, because POFs are so flexible that they can withstand larger strain of several tens of percent (even 100% [12]). To date, various strain and temperature sensors using POFs have been developed, including those based on fiber Bragg gratings [13,14], modal interference [15][16][17], Brillouin scattering [18][19][20][21][22][23][24][25], and Rayleigh scattering [26][27][28][29].…”