Temperature-independent hygrometry using micromachined photonic crystal fiber
An in-fiber Mach–Zehnder interferometer (MZI) is proposed and experimentally demonstrated for relative humidity (RH) and temperature measurements. The MZI is formed by a grapefruit-shaped photonic crystal fiber (G-PCF) cascaded with a short section of multimode fiber that serves as a mode coupler. T...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Published: |
Optical Society of America
2018
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| Subjects: | |
| Online Access: | http://eprints.um.edu.my/20170/ https://doi.org/10.1364/AO.57.004237 |
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| Summary: | An in-fiber Mach–Zehnder interferometer (MZI) is proposed and experimentally demonstrated for relative humidity (RH) and temperature measurements. The MZI is formed by a grapefruit-shaped photonic crystal fiber (G-PCF) cascaded with a short section of multimode fiber that serves as a mode coupler. To enhance sensitivity to humidity, femtosecond laser micromachining was performed to remove a portion of cladding of the G-PCF to expose its core to the ambient medium. The output interference spectrum is fast Fourier transformed to produce a spatial frequency spectrum that describes the intensity composition of the cladding modes in the MZI. In our investigation, it was observed that the interference dip intensity has a sensitivity of −0.077 dB=% RH to the change of RH in the range of 25%–80% RH, whereas the dip wavelength has a temperature sensitivity of ∼3.3 pm∕°C in the range of 25°C–70°C. In addition, the dip intensity was insensitive to temperature. These characteristics have provided convenience in eliminating temperature cross talk and achieving accurate humidity measurement. |
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