Zhenggang Lian

Bio: Zhenggang Lian is an academic researcher from University of Southampton. The author has contributed to research in topics: Photonic-crystal fiber & Optical fiber. The author has an hindex of 13, co-authored 63 publications receiving 564 citations. Previous affiliations of Zhenggang Lian include University of Nottingham.

An open-cavity Fabry-Perot interferometer with PVA coating for simultaneous measurement of relative humidity and temperature

Abstract: A fiber-optic open-cavity Fabry-Perot (FP) interferometer (FPI) with polyvinyl alcohol (PVA) coating is proposed and experimentally demonstrated for simultaneous measurement of relative humidity (RH) and temperature. The FPI consists of an etched side-hole fiber (SHF) sandwiched in between two leading single-mode-fibers. The PVA film is plated on the fiber surface functioning as a humidity-to-refractive index (RI) transducer. Theoretical analysis details the RH and temperature influence on the spectral fringes of the FPI. Experimental results confirms and show that, the reflection loss of the FPI nonlinearly decreases more than 15 dB when the RH increases from 30%RH to 90%RH with a highest sensitivity of −1.2 dB/%RH, while the dip wavelength of the spectral fringe exhibits linear RH and temperature sensitivities of −23.1 pm/%RH and −6.14 pm/°C, respectively. Thus, by monitoring the reflection and wavelength of the interference dip, the proposed sensor enables accurate simultaneous measurement of RH and temperature. A fast and reversible time response has also been demonstrated. Such excellent sensing performance with compactness, ease of fabrication makes our sensing structure a highly promising candidate for RH and temperature monitoring applications.

Embossing of chalcogenide glasses: monomode rib optical waveguides in evaporated thin films.

Abstract: Single-mode optical rib waveguides operating at telecommunication wavelengths are successfully patterned via a hot embossing technique in a thermally evaporated chalcogenide glass thin film on a chalcogenide glass substrate. Ellipsometry is used to measure the refractive index dispersion of the pressed film (As40Se60) and substrate (Ge17As18Se65).

Single-polarization single-mode double-ring hollow-core anti-resonant fiber.

Abstract: A novel single-polarization single-mode double-ring hollow-core anti-resonant fiber with two single-polarization regions (1545–1553 nm and 1591–1596 nm) is proposed. Single-polarization guidance is achieved by coupling a polarized fundamental mode and silica mode by using different tube thicknesses. Specifically, when the wavelength is 1550 nm, only a single x-polarized fundamental mode with a low loss of 0.04 dB/m is propagated by a polarization extinction ratio of 17662 and minimum higher-order mode extinction ratio of 393 by optimizing the structural parameters. Furthermore, this fiber also exhibits high-performance bend resistance. The x-polarized FM loss is as low as 0.11 dB/m with single-polarization single-mode guidance when the proposed fiber was bent at a bend radius of 8 cm toward the x-direction.

Hybrid-cavity fabry-perot interferometer for multi-point relative humidity and temperature sensing

Abstract: A novel hybrid-cavity Fabry-Perot interferometer (HFPI) is theoretically proposed and experimentally demonstrated. The hybrid micro-cavity structure is consisted of a short segment of four-hole suspended-core fiber (SCF) and attaching moderate optical adhesive as the hygroscopic material. Due to the different sensitivities of the hybrid Fabry-Perot (F-P) cavities to the relative humidity (RH) and temperature, both information can be simultaneously demodulated by utilizing the phase-shift tracking scheme in the Fast Fourier Transform (FFT) spectra. The precise micromanipulation of each cavity length ensures the separation of each amplitude peak in the FFT spectra, which renders this HFPI multi-point sensing capability. Experimental tests were carried out, and the results indicate that the proposed HFPI with excellent sensing performance is a promising platform for multi-point RH and temperature sensing applications.

A refractive index sensor based on a D-shaped photonic crystal fiber with a nanoscale gold belt

Abstract: A novel refractive index sensor based on a D-shaped photonic crystal fiber with a nanoscale gold belt is proposed. The nanoscale gold belt is deposited on the flat surface to produce surface plasmon resonance. Numerical results show that the refractive index sensor has a broad measurement range which is from 1.2 to 1.4 and the maximum sensitivity can reach to 3751.5 nm/RIU. The refractive index resolution of the sensor is under 1 × 10−5 RIU in the whole measuring range. A high adjusted R-squared, up to 0.99002, is acquired from the fitting curve of the resonance wavelength. The sensor is sensitive to the variation of the refractive index of analytes and can be applied to the fields of chemical and biological sensing field.

Phd by thesis

Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Supercontinuum generation, photonic crystal fiber

Abstract: A topical review of numerical and experimental studies of supercontinuum generation in photonic crystal fiber is presented over the full range of experimentally reported parameters, from the femtosecond to the continuous-wave regime. Results from numerical simulations are used to discuss the temporal and spectral characteristics of the supercontinuum, and to interpret the physics of the underlying spectral broadening processes. Particular attention is given to the case of supercontinuum generation seeded by femtosecond pulses in the anomalous group velocity dispersion regime of photonic crystal fiber, where the processes of soliton fission, stimulated Raman scattering, and dispersive wave generation are reviewed in detail. The corresponding intensity and phase stability properties of the supercontinuum spectra generated under different conditions are also discussed.

Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications

Abstract: This is the first comprehensive review on methods and materials for use in optical sensing of pH values and on applications of such sensors. The Review starts with an introduction that contains subsections on the definition of the pH value, a brief look back on optical methods for sensing of pH, on the effects of ionic strength on pH values and pKa values, on the selectivity, sensitivity, precision, dynamic ranges, and temperature dependence of such sensors. Commonly used optical sensing schemes are covered in a next main chapter, with subsections on methods based on absorptiometry, reflectometry, luminescence, refractive index, surface plasmon resonance, photonic crystals, turbidity, mechanical displacement, interferometry, and solvatochromism. This is followed by sections on absorptiometric and luminescent molecular probes for use pH in sensors. Further large sections cover polymeric hosts and supports, and methods for immobilization of indicator dyes. Further and more specific sections summarize the state of the art in materials with dual functionality (indicator and host), nanomaterials, sensors based on upconversion and 2-photon absorption, multiparameter sensors, imaging, and sensors for extreme pH values. A chapter on the many sensing formats has subsections on planar, fiber optic, evanescent wave, refractive index, surface plasmon resonance and holography based sensor designs, and on distributed sensing. Another section summarizes selected applications in areas, such as medicine, biology, oceanography, bioprocess monitoring, corrosion studies, on the use of pH sensors as transducers in biosensors and chemical sensors, and their integration into flow-injection analyzers, microfluidic devices, and lab-on-a-chip systems. An extra section is devoted to current challenges, with subsections on challenges of general nature and those of specific nature. A concluding section gives an outlook on potential future trends and perspectives.

Relative humidity sensor based on hollow core fiber filled with GQDs-PVA

Abstract: A novel optic fiber Fabry-Perot interferometer (FPI) based on graphene quantum dots (GQDs) and Polyvinyl Alcohol (PVA) is first proposed for relative humidity (RH) sensing and experimentally demonstrated. The GQDs-PVA compounds are filled into the hollow core fiber (HCF), which is spliced at the end of a single mode fiber (SMF). The refractive index of GQDs-PVA compounds reduces and the length of the FP cavity elongates with the increase of RH, which will lead the reflective spectrum shift to length wavelength, and the variation can characterize the change of RH values. The humidity environment is generated by different saturated saline solution, and the RH values are calibrated by a moisture meter. Experiment results reveal that the wavelength shift shows good linearity with the RH changing from 13.47%RH to 81.34%RH, and the sensitivity is 117.25 pm/%RH with the linearity relevancy of 0.9983. In addition, reversibility and repeatability experiments are carried out and the mean square deviation of six sets of data is 1.425 × 10−3, which indicates good practical development prospects. Taking the practical application into account, the influence of hydrogen and nitrogen in the air on the sensor is studied before humidity experiment, and the experiment results shows that hydrogen and nitrogen in the air have a negligible effect on the humidity sensor proposed in this paper.