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Cascaded Mach-Zehnder interferometers with Vernier effect for gas pressure sensing
摘要： We propose a compact ultrasensitive gas pressure fiber sensor based on cascaded Mach-Zehnder interferometers (MZI) with Vernier effect. Each MZI is composed of a hollow core fiber (HCF) sandwiched in between two short multimode fibers (MMF). The lengths of the HCFs in the two MZIs are set a little different in order to generate an envelope in the transmission spectrum of the cascaded structure for Vernier effect sensing. The HCF in one MZI is opened to make the air hole connect to the external environment and act as sensing element. The HCF in the other MZI is kept closed serving as reference element. The two MZIs have quite different responses to changes in gas pressure, but have almost the same response to temperature variation. Therefore, the Vernier effect occurs when the gas pressure changes, but not when the temperature varies. As a result, the proposed structure has an ultra-high gas pressure sensitivity with a quite low temperature cross-sensitivity. Experimental results show that the gas pressure sensitivity referring to the envelope of the proposed sensor is -73.32 nm/MPa in the range of 0 - 0.8 MPa, with a temperature cross-sensitivity of only 0.72 kPa/°C.
关键词： Vernier effect,gas pressure,Hollow core fiber,Mach-Zehnder interferometer
更新于2025-11-28 14:23:57
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Theoretical demonstration of Single polarization single mode hollow core anti-resonance fiber using surface plasmon resonance
摘要： We designed a hollow core anti-resonance fiber based on surface plasmon resonance and optimized its characteristics by using the finite element method with perfectly matched layer boundary condition. A single mode single polarization bandwidth, up to 200 nm, is obtained by employing surface plasmon resonance which is produced by two embedded gold wires. Only the x-polarized fundamental mode of the fiber suffers a high loss because of the surface plasmon resonance. In addition, single mode guidance is obtained by adjusting the size of cladding tubes. Simulation results show that the designed fiber has an effective single polarization single mode guidance in the wavelength range from 1.3 to 1.5μm. In this range, both the higher order mode extinction ratio and the polarization mode extinction ratio are more than 100. The structure is shown to have a good fabrication tolerance with respect to variations in the position and size of the gold wires. The proposed fiber has many potential applications in polarization splitters, fiber-optic gyroscopes and polarization-dependent fiber systems.
关键词： Anti-resonance hollow core fiber,Surface plasmon resonance,Single polarization single mode.
更新于2025-09-23 15:23:52
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Enhanced Raman Detection System based on a Hollow-core Fiber Probe design
摘要： This paper focus on an enhanced Raman-based detection probe and its performance evaluated. The probe employs a hollow-core fiber design to allow liquid micro-sample to be analyzed. The hollow-core fiber is used both to transmit the light signal used to excite the sample and to collect the Raman scattering signal received from the micro-sample under analysis. In order to maximize the performance of the system, various parameters have been studied experimentally, including the diameter and the height of the liquid sample in the probe. The aim has been optimizing both as a means to enhance the Raman scattering signal received from the liquid sample. As a result, a Raman-based detection probe using a reflector approach was developed and evaluated. This design enabling a greater area for interaction with the sample to be formed and to concentrate the excitation light into it. This then increases the efficiency of the light-liquid interaction and improves the collection efficiently of the forward Raman scattering light signal. With the use of this design, the detected Raman scattering signal was increased by a factor of 103~104 over what otherwise would be achieved. A key feature is that with the use of a hollow-core fiber to collect the liquid sample, only a very small volume is needed, making this well suited to practical applications where limited amounts of material are available e.g. biofluids or high value liquids. The system designed and evaluated thus provides the basis of an effective all-fiber Raman-based detection system, capable of being incorporated into portable analysis equipment for rapid detection and in-the-field use.
关键词： small liquid sample measuring method,enhanced structure,Raman detection probe,Hollow-core fiber (HF)
更新于2025-09-23 15:21:21
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A high sensitivity optical fiber strain sensor based on hollow core tapering
摘要： An optical fiber strain sensor based on a Mach-Zehnder interferometer (MZI) is demonstrated experimentally. The sensor is fabricated by fusion splicing a tapered hollow core fiber (THCF) with a 500 μm taper region between two single mode fibers (SMFs). Tapering on the HCF increases the sensor’s strain sensitivity to 2.7 pm/με in a measurement range of 0 με to 2100 με, 1.5 times larger than that of all-fiber MZI strain sensors without tapered areas (approximately 1.8 pm/με). The experimental results show that the sensor has good stability and repeatability. This sensor has high strain sensitivity and low temperature sensitivity and can be used in environments with little temperature fluctuation.
关键词： Mach-Zehnder interferometer,Optical fiber sensor,Tapered hollow core fiber
更新于2025-09-23 15:19:57
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Anti-resonant reflecting effect in large-core hollow-core photonic crystal fiber for temperature sensing
摘要： Optical fiber sensors based on anti-resonant reflecting effect have attracted widespread attention in recent years. Here, a compact and robust all-fiber device is proposed and developed based on anti-resonant reflecting effect. A double-layered Fabry-Pérot resonator is built by infiltrating alcohol into two adjacent cladding holes of a new large-core hollow-core photonic crystal fiber. Due to the thermo-optic effect of alcohol, the temperature sensitivity of -0.184 nm/oC is achieved. This device can be good candidates in the field of physical or bio/chemical sensing.
关键词： Anti-resonant reflecting effect,Hollow core fiber,Fiber optic sensors
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - In-fiber Surface Plasmon Resonance Temperature Sensor Based on PDMS Infiltrated Hollow Core Fiber
摘要： An in-fiber surface plasmon resonance temperature sensor based on Polydimethylsiloxane infiltrated hollow core fiber was experimentally proposed and demonstrated. Results demonstrated that the proposed sensor behaved high sensitivity of -1.05nm/℃, small size, and good stability.
关键词： Surface plasmon resonance,Hollow core fiber,Polydimethylsiloxane,Temperature sensor
更新于2025-09-16 10:30:52
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Passive, Broadband, and Low-Frequency Suppression of Laser Amplitude Noise to the Shot-Noise Limit Using a Hollow-Core Fiber
摘要： Reducing noise to the shot-noise limit is a challenge for laser development for ultrasensitive applications in precision sensing and fundamental science. We use hollow-core ?ber in a collinear-balanced-detection scheme to suppress 2.6 dB of amplitude noise to within 0.01 dB of the shot-noise limit, while simultaneously preserving the spectrum and temporal pro?le of picosecond laser pulses. We also provide an enhanced version of the scheme that concatenates multiple circuits for suppression over many frequencies and broad frequency ranges. We perform a ?rst demonstration of this method and reduce total excess amplitude noise, between 2 and 6 MHz, by 85%. These demonstrations enable passive, broadband, all-guided ?ber-laser technology operating at the shot-noise limit.
关键词： shot-noise limit,collinear-balanced-detection,laser amplitude noise,hollow-core fiber,noise suppression
更新于2025-09-12 10:27:22
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Broadened-laser-driven polarization-maintaining hollow-core fiber optic gyroscope
摘要： A state-of-the-art fiber optic gyroscope (FOG) using a 250-m quadrupolar-wound coil of polarization-maintaining hollow-core fiber (HCF) interrogated by a broadened laser is demonstrated. The fiber coil is directly connected to the multi-function integrated optics chip (MIOC) to reduce instabilities and reflections. The HCF FOG is first driven with a broadband source, yielding an angular random walk (ARW) of 2.12 μrad/√Hz and a drift of 0.375 μrad. This drift is 3.4 times lower than reported in any previous HCF FOG. Measuring the loss and ARW versus wavelength of the HCF FOG driven by a tunable narrow-linewidth laser reveals that the HCF supports a dense spectrum of high-scattering surface modes (~70 modes/nm). The HCF FOG was also interrogated with a 22.5-GHz broadened-laser source, yielding an ARW of 6 μrad/√Hz. This ARW is most likely limited by backscattering mediated by coupling to the high-scattering surface modes. The drift of the HCF FOG driven by the broadened laser was 0.88 μrad. This drift is limited by polarization coupling, and confirms the holding parameter given by the fiber provider for this fiber (10-3 m-1).
关键词： Surface modes,Fiber optic gyroscope,Hollow-core fiber
更新于2025-09-11 14:15:04