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۱Investigation of the bias current and frequencyd ependenceo f the d ete ctivity of high– f. supercon du ctor transition–edge 1l? detectors
اطلاعات انتشار: پانزدهیمن کنفرانس مهندسی برق ایران، سال
تعداد صفحات: ۵
Voltage noise is a critical parameter for high sensitive bolometric IR detectors because it determines the detectivity for these types of devices. Intrinsic volt noise measurement for superconducting transition–edge bolometers made of YBCO thin film is reported in this paper. Dependency of intrinsic noise with respect to temperature in the vicinity of critical temperature is obtained for various vqlues of bias current and chopping frequencies. Effect of these two parameters on dilferent noise types –fo, superconductor is investigated. Three maior types of voltages noise were identified in our sample according to were they occurred in temperature relative to T, (,nset and the zero resistance temperature, T, ,"n,, and the dependence of the obsemed noise signal on frequency and bias current presented.<\div>

۲Analytical Calculation of Frequency Response of YBCO Thin Film Bolometer
اطلاعات انتشار: شانزدهیمن کنفرانس مهندسی برق ایران، سال
تعداد صفحات: ۶
Here we present a new approach for analytical modelling and calculation of the response of superconductive transition edge bolometers in a wide range of modulation frequency and for different configuration of the film patterns. The method used here is based on solving the heat transfer differential equation for two different time varying heat sources related to the absorbed radiated power with considerations of two–dimensional boundary conditions for the case of meander line patterned devices. Method is developed to matches phase and magnitude of frequency response with measurements much better than previous approximation. Using this approach we have also investigated the effect of track width and spacing on the magnitude of bolometric response. The method is also capable of being used for analysis of other configurational parameters. In this calculation the effect of surface absorption caused by the thin film and absorber layer as well as bulk absorption in the depth of substrate is considered. Analytical results are presented and also compared with previous analytical work and the measured data.<\div>

۳Detectivity of YBCO Transition Edge Bolometer as a Function of Chopping Frequency, Bias Current and Coating
اطلاعات انتشار: شانزدهیمن کنفرانس مهندسی برق ایران، سال
تعداد صفحات: ۵
Bolometric response and noise characteristics of YBCO superconductor transition edge IR detectors with relatively sharp transition and its resulting detectivity are investigated. The magnitude of response of a device was obtained in different bias currents and modulation frequencies. Also dependency of intrinsic noise of the device with respect to the bias temperature in the vicinity of critical temperature was studied for various values of bias currents and chopping frequencies. Having measured the bolometric response and noise characteristics, we found the device detectivity versus frequency in different bias currents and analyzed the results. We also improved the detectivity of the device by increasing surface absorptance using a novel infrared absorber, which is made of a Copper–Carbon composite, coated in a low temperature process. Within the modulation frequency range studied in this investigation, comparison of device responsivity before and after the coating is also presented.<\div>
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