Rancang Bangun Sensor Getaran Berbasis Serat Optik Quasi-Distributed Berstruktur SMS (Singlemode-Multimode-Singlemode)

Pratiwi, Nabilla Nurul (2026) Rancang Bangun Sensor Getaran Berbasis Serat Optik Quasi-Distributed Berstruktur SMS (Singlemode-Multimode-Singlemode). Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Sensor getaran konvensional seperti akselerometer memiliki keterbatasan dalam pemantauan getaran pada area yang tersebar luas. Penelitian ini merancang sensor getaran serat optik quasi distributed berstruktur Singlemode-Multimode Singlemode (SMS) dengan variasi panjang Multimode Fiber (MMF) sebesar 1 cm, 2 cm, 3 cm, dan 4 cm. Sistem menggunakan sumber cahaya ASE broadband pada rentang 1430–1660 nm, Optical Spectrum Analyzer (OSA) untuk pengukuran spektrum, motor DC sebagai sumber getaran, serta Optical Time Domain Reflectometer (OTDR) untuk mendeteksi gangguan sepanjang serat optik. Pengujian dilakukan pada kondisi baseline, variasi frekuensi getaran, dan menggunakan serat singlemode (SMF) tanpa struktur MMF sebagai pembanding. Respons sensor dianalisis berdasarkan perubahan panjang gelombang puncak (Δλ), perubahan daya optik (ΔP), dan sensitivitas yang diperoleh dari kemiringan (slope) regresi linear terhadap frekuensi getaran. Pada pengujian baseline menunjukkan bahwa variasi panjang MMF menghasilkan perubahan posisi panjang gelombang puncak pada rentang 1526,58–1554,87 nm, dengan daya optik tertinggi sebesar −31,618 dBm pada struktur SMS 3 cm. Hasil pengujian menunjukkan bahwa sensitivitas sensor getaran terhadap pergeseran panjang gelombang pada struktur SMS 2 cm merupakan yang tertinggi, yaitu sebesar 0,076 nm/Hz, dengan Δλ mencapai 7,137 nm pada frekuensi 97,79 Hz. Sensitivitas sensor getaran terhadap perubahan daya optik pada struktur SMS 1 cm merupakan yang tertinggi, yaitu sebesar 0,038 dB/Hz, dengan perubahan daya sekitar −3,9 hingga −4,0 dB pada rentang pengujian. Pengukuran menggunakan singlemode fiber (SMF) tanpa MMF menghasilkan Δλ maksimum sebesar 0,702 nm. Pengujian OTDR menunjukkan peningkatan total loss dari 0,152 dB pada kondisi baseline menjadi 0,263 dB dan 0,534 dB pada variasi macrobending, serta kemunculan event pada lokasi gangguan. sehingga mendukung kemampuan sistem dalam mendeteksi gangguan sepanjang jalur serat. Hasil penelitian menunjukkan bahwa sensor SMS mampu mendeteksi variasi getaran berdasarkan perubahan panjang gelombang dan daya optik serta memiliki potensi untuk dikembangkan sebagai sistem pemantauan getaran quasi-distributed. ===================================================================================================================================
Conventional vibration sensors such as accelerometers, have limitations in monitoring vibrations over widely distributed areas. This study designs a quasi-distributed fiber-optic vibration sensor based on a Singlemode-Multimode-Singlemode (SMS) structure with Multimode Fiber (MMF) lengths of 1 cm, 2 cm, 3 cm, and 4 cm. The system uses a broadband ASE light source in the wavelength range of 1430–1660 nm, an Optical Spectrum Analyzer (OSA) for spectral measurements, a DC motor as the vibration source, and an Optical Time Domain Reflectometer (OTDR) for detecting disturbances along the optical fiber. Measurements were conducted under baseline conditions, various vibration frequencies, and using singlemode fiber (SMF) without an MMF structure as a comparison. The sensor response was analyzed based on the peak wavelength shift (Δλ), optical power change (ΔP), and sensitivity obtained from the slope of linear regression against vibration frequency. The baseline measurements showed that variations in MMF length resulted in peak wavelength positions ranging from 1526.58 to 1554.87 nm, with the highest optical power of −31.618 dBm obtained from the 3 cm SMS structure. The results showed that the vibration sensor sensitivity to peak wavelength shift was highest for the 2 cm SMS structure, with a sensitivity of 0.076 nm/Hz and a maximum Δλ of 7.137 nm at a frequency of 97.79 Hz. The highest sensitivity to optical power change was obtained from the 1 cm SMS structure, with a sensitivity of 0.038 dB/Hz and an optical power change of approximately −3.9 to −4.0 dB over the measurement range. Measurements using SMF without MMF produced a maximum Δλ of 0.702 nm. OTDR measurements showed an increase in total loss from 0.152 dB under baseline conditions to 0.263 dB and 0.534 dB under macrobending variations, along with the appearance of events at the disturbance locations, supporting the system's capability to detect disturbances along the optical fiber. The results demonstrate that the SMS sensor can detect vibration variations through changes in peak wavelength and optical power and has potential for further development as a quasi-distributed vibration monitoring system.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Quasi Distributed, Serat Optik, Sensor Getaran, Singlemode-Multimode-Singlemode (SMS), Optical Spectrum Analyzer.=================================================== Quasi Distributed, optical fiber, vibration, Optical Spectrum Analyzer, 1550 nm wavelength.
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) > TA1573 Detectors. Sensors T Technology > TA Engineering (General). Civil engineering (General) > TA1800 Fiber Optics T Technology > TA Engineering (General). Civil engineering (General) > TA1815 Optical fiber detectors. Bragg gratings. T Technology > TA Engineering (General). Civil engineering (General) > TA355 Vibration.
Divisions:	Faculty of Vocational > Instrumentation Engineering
Depositing User:	Nabilla Nurul Pratiwi
Date Deposited:	19 Aug 2026 07:08
Last Modified:	19 Aug 2026 07:08
URI:	http://repository.its.ac.id/id/eprint/144366

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