Study On The Characteristics Of Temperature Sensor Based On The Quantum Dot Thin Film And Photonic Crystal Fiber

Temperature sensor is widely applied in many domains,such as the daily life,aerospace and agricultural production.Common temperature sensors include thermocouple,heat res istance and infrared sensors etc.Although these temperature sensors have many advantages,such as low cost,simple structure and mature technology,there are some potential dangers due to the electromagnetic effect.So they do not meet the requirements in the some high-risk areas.In this work,a novel temperature sensor based on quantum dots(QDs)thin film or QDs-doped photonic crystal fiber(PCF)is studied.It simultaneously uses the temperature effect of the three optical parameters of QDs photoluminescence(PL)—the peak wavelength,the peak intens ity,the full width at half maxima(FWHM)— to measure the environment temperature,and has some unique advantages,including anti-electric magnetic field interference,high accuracy,high resolution,good dynamic response and wide measure range and so on.Therefore,it can be used to the temperature detection in the extreme conditions and has a wide application prospect.The research contents include:(1)With finite element method,a photonic crystal fiber with two zero-dispersion dots and CdSe/ZnS QDs film is designed firstly.And then the dispersion and loss characteristics of the designed PCFs are analyzed.The research results show that the PCF with Cd Se/ZnS quantum dots films exist the fundamental modes along the x-and y-axes of fibers.As pump wavelength increases,their dispersions increase first and then decrease along the x-and y-axes of fiber.The losses of PCFs are close to zero in the visible region while they increase gradually in the infrared region.By adopting the QDs selectively,the loss of PCF with the Cd Se/ZnS QDs nanofilms inside the air holes only around the core can be improved.These research results show that the dispersions and losses of the PCF can be controlled effectively in experiment by depositing the Cd Se/ZnS QDs films and choosing a suitable pump wavelength.(2)Based on the temperature-dependence characteristic of three optical parameters(peak wavelength,peak intens ity and FWHM)of CdSe/ZnS core-shell QDs PL spectra and the advantages of PCF fiber,a multi-parameter PCF fiber temperature sensor doped the CdSe/ZnS QDs is designed.The optical temperature-dependence properties of QDs PL spectra are studied in detail,such as the peak intens ity of PL spectra,the peak wavelengths of PL spectra,the energy band-gap of the QDs,FWHM of PL spectra,the self-referenced peak intens ity of PL spectra and so on.The research results indicate that,when the temperature is changed from 30 to 100?,the intensity of PL spectra decreases gradually,while its peak wavelength and FWHM increase gradually.Further analys is shows that the peak wavelengths of PL spectra,the energy band-gap of the QDs and the self-referenced peak intensity of PL spectra vary linearly with the temperature,and the FWHM varies quadratic curve with the temperature,and the peak intens ity of PL spectra can be represented by exponential function with the temperature.These measured results are in good agreement with the theoretical analysis.Moreover,according to the red shift of the peak wavelengths of PL spectra,the average resolution of the designed reflective fluorescence QDs temperature sensor can reach 0.062 nm/?.(3)Making use of home-made dual-granularity droped CdSe/ZnS QDs thin films,a reflective fluorescence temperature sensor is also designed and fabricated.As a core component of the temperature sensor,the dual-granularity doped CdSe/ZnS QDs thin film(QD540 and QD610)embedded in sensing sensor is used to establish a refractive temperature sensor.Then,adopting the analyzing method of the PL spectra from the doped CdSe/ZnS QDs PCF,multi-parameter temperature-dependence properties of the PL spectra of dual-granularity Cd Se/ZnS QDs are studied,inc luding the intensity,the peak wavelengths and FWHM of PL spectra,the energy band-gap of the QDs and the self-referenced peak intens ity of PL spectra etc.Experimental results show that,an about 150 nm wide spectra with two spectral peaks is obtained first.When the temperature is changed from 30 to 100?,the variation rule of the broadband spectrum is similar to the emission spectrum of QDs PCF fiber.Its intens ity decreases gradually with the increase of temperature.The peak wavelengths,the self-referenced intensity of dual emission peaks,and the energy bandgaps of the QDs also vary linearly with the temperature,while its FWHM and peak intensity also generate nonlinear variation similar to the QDs PCF fiber.Moreover,the self-referenced peak intensity of PL spectra from QDs thin film has a high stability during the temperature increasing and decreasing.Finally,the average resolution of the designed reflective QDs temperature sensor can reach 0.055 nm/? by optimizing the sensing system.