RESUMO
Non-intrusive, wide bandwidth and spatial resolution are terms often heard in electric field sensing. Despite of the fact that conventional electromagnetic field probes (EMF) can exhibit notable functional performances, they fail in terms of perturbation of the E-field due to their loaded metallic structure. In addition, even though electro-optical technology offers an alternative, it requires large interaction lenghts which severely limit the sensing performances in terms of bandwidth and spatial resolution. Here, we focus on miniaturizing the interaction volume, photon lifetime and device footprint by taking advantage of the combination of lithium niobate (LN), Lab-on-Fiber technologies and photonic crystals (PhC). We demonstrate the operation of an all-dielectric E-field sensor whose ultra-compact footprint is inscribed in a 125 µm-diameter circle with an interaction area smaller than 19 µm × 19 µm and light propagation length of 700 nm. This submicrometer length provides outstanding bandwidth flatness, in addition to be promising for frequency detection beyond the THz. Moreover, the minituarization also provides unique features such as spatial resolution under 10 µm and minimal perturbation to the E-field, accompanied by great linearity with respect to the E-field strength. All these specifications, summarized to the high versatibility of Lab-on-Fiber technology, lead to a revolutionary and novel fibered E-field sensor which can be adapted to a broad range of applications in the fields of telecommunications, health and military.
RESUMO
The results presented in this paper are part of a project aimed at designing an original solution for the treatment of used disposable diapers permitting the recycling of materials and the recovery of energy. Diapers must be collected separately at source and transported to an industrial facility to undergo special treatment which makes it possible to separate plastics and to recover a biodegradable fraction (BFD) made up mainly of cellulose. The methane yield of BFD was measured and found to be 280 ml CH4/g VSfed on average. 150 kg of dry BFD can be retrieved from the treatment of one ton of used disposable diapers, representing an energy potential of about 400 kW h of total energy or 130 kW h of electricity. As the treatment process for used diapers requires very high volumes of water, the setting up of the diaper treatment facility at a wastewater treatment plant already equipped with an anaerobic digester offers the advantages of optimizing water use as well as its further treatment and, also, the anaerobic digestion of BFD. The lab-scale experiments in a SBR showed that BFD co-digestion with sewage sludge (38% BFD and 62% waste activated sludge on volatile solids basis) was feasible. However, special attention should be paid to problems that might arise from the addition of BFD to a digester treating WAS such as insufficient mixing or floating particles leading to the accumulation of untreated solids in the digester.