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Submersion Sensor with Side-Polished Fiber and Planar Waveguide in Manhole
Abstract
Experiments are conducted to investigate whether a side-polished fiber sensor can detect submersion without being affected by water impurities when a manhole is submerged. The side-polished fiber sensor is also examined whether it can detect submersion when the overlay of such sensor is covered with impurities.
... To monitor the submersion, various water sensors have been developed using optical fiber bending [1], hydrogel fiber [2,3] and side-polished fibers [4][5][6]. The sensors based on the fiber bending and hydrogel fiber use swelling materials. ...
... However, it takes time for the swelling materials to absorb water, so real-time monitoring is difficult and it is also difficult to reuse the swelling materials. Recently, several submersion sensors have been developed using side-polished optical fibers [4][5][6], which have the advantages of an immediate response, high recurrence, low insertion loss, mechanical stability, and simple fabrication process. Transmission-type [4][5] and reflective-type [6] side-polished optical fiber submersion sensors were developed. ...
... Recently, several submersion sensors have been developed using side-polished optical fibers [4][5][6], which have the advantages of an immediate response, high recurrence, low insertion loss, mechanical stability, and simple fabrication process. Transmission-type [4][5] and reflective-type [6] side-polished optical fiber submersion sensors were developed. A reflection-type side-polished optical fiber submersion sensor provided efficient remote sensing. ...
The submersion monitoring system based on a reflective side-polished optical fiber submersion sensor with an optical fiber mirror was shown to be an effective alarm system with remote monitoringwhen the drainage capacity of a common utility duct is exceeded due to heavy rainfall. The proposed sensor was connected to an existing installed optical fiber network at a height of 250mm in a common utility duct, and then tested under sample materials(distilled water, river water, sea water, foul water, muddy water, petroleum, edible oil) at a distance of 1km from the sensor for remote sensing. In experiments, the proposed real-time sensor system reduced maintenance cost and improved monitoring efficiency by using a reflection-type side-polished optical fiber submersion sensor efficient for remote monitoring of a common utility duct.
... Therefore, these submerged locations need to be detected and restored to normal conditions as quickly as possible. Thus, to detect the occurrence of submersion and enable a speedy recovery of the optical fiber networks to normal conditions, various submersion sensors have been developed using optical fiber bending [1], [2] and side-polished optical fibers [3], [4], where side-polished optical fiber submersion sensors have demonstrated the advantages of an immediate response, high recurrence, low insertion loss, mechanical stability, and simple fabrication process. However, since conventional side-polished optical fiber submersion sensors are transmission-type devices, their use is restricted as regards measuring long distances. ...
A reflection-type side-polished optical fiber submersion sensor (RSS) with an optical fiber mirror for remote sensing is proposed. When compared with a conventional transmission-type side-polished optical fiber submersion sensor (TSS), the RSS with an optical fiber mirror provides an improved response, and allows efficient remote submersion sensing. In experiments, the RSS with an optical fiber mirror detected submersion with 1 dB increased throughput power gain when compared with a conventional TSS, and provided efficient remote sensing at a distance of 1 km based on the resonance wavelength shift and transmission power gain
A reflection-type side-polished optical fiber submersion sensor with an optical fiber mirror in a manhole is proposed. When this sensor is submerged into distilled water in a manhole and the measurement is made at about 1km from the sensor, the throughput power gain is changed by about 2.04dB at 1540nm and the resonance wavelength shifts from 1540nm to 1541.6nm.
The characteristics of light propagation in and the coupling of a fiber-slab coupler with a buffer layer were obtained through the coupled-mode theory. The results were found to highly depend not only on the refractive index of the buffer layer but also on the thickness of the buffer layer. The fiber-slab coupler was modeled as a fiber-to-slab waveguide coupler with four layers, including a fiber cladding layer, a buffer layer, a slab waveguide layer and an overlay material layer. The refractive index and the thickness of the buffer layer for effective coupling were gained by tuning. More of the light's power was transferred when the refractive index of the buffer layer was very close to that of the slab waveguide and when the thickness of the buffer layer was almost the same as that of the slab waveguide. We were able to obtain a buffer layer with favorable characteristics for achieving the desirable coupling performance.
We report on the design, construction and test of a generic form of sensor for making distributed measurements of a range of chemical parameters. The technique combines optical time-domain reflectometry with chemically sensitive water-swellable polymers (hydrogels). Initial experiments have concentrated on demonstrating a distributed water detector; however, gels have been developed that enable this sensor to be readily adapted to distributed pH measurements.
A number of in-line components utilizing the evanescent coupling between a side-polished fiber and a high-index slab overlay have recently been demonstrated. The wavelength response of the structure shows a series of resonances, the position of which must be precisely controlled for practical applications. We present experimental and theoretical results for the tuning of the resonance position through variation of the superstrate parameters.
For monitoring the presence of water at the splicing points of an optical fiber, the water detection sensors based on a side-polished fiber coupler with a commercial microscope-cover-glass are proposed. The sensors are very sensitive to the variation of an upper cladding layer’s index on the overlay waveguide. When the sensors detect water, the coupling wavelengths shift to longer wavelength at about 2nm than that of an air cladding. The variation of an optical loss as a function of the wavelength shift is monitored using an optical time-domain refractometry to detect the installed positions and the immersion locations of the sensors. The advantages of our sensor for these purposes are discussed in.
The coupling of optical power between a fibre, side polished close to the core, and a planar multimode waveguide overlay is highly wavelength selective. Vacuum deposited films and polished lithium niobate have been used in the role of the overlay and a wavelength resolution of 3 nm (with subnanometre feasibility) has been demonstrated with losses of less than 0.2 dB. Electro-optic tunability in the region of a few nanometres was also observed for the lithium niobate devices.
In optical-fiber networks, it is important to monitor water which
seeps into splice enclosures. The fibers have residual stress at
splicing points, and when water is present, this adversely affects fiber
lifetime. A water sensor which has a simple structure for monitoring
water at splicing points has been developed. This water sensor causes
optical loss due to fiber bending when water seeps into splicing
enclosures. The design method using a fiber-bending model and sensor
performance are described