CAJ | 학술논문

在基于Kramers-Kronig(K-K)关系求解太赫兹(THz)频段介质的折射率和吸收系数时,针对反射率高频端外延指数函数的指数因子的确定问题,提出采用时域有限差分(FDTD)算法模拟优化指数因子的方法,从而保证提取介质折射率和吸收系数的精确性.该方法根据FDTD算法模拟与实测样品时域信号的最小二乘差来确定指数因子,当最小二乘差取极小值时所对应的指数因子即为最优解.葡萄糖多晶粉末压片的实验表明,采用本文所提出的利用FDTD算法模拟优化确定的指数因子为0.495,当用K-K关系求解折射率和吸收系数时得到的结果更加精确.
재기우Kramers-Kronig(K-K)관계구해태혁자(THz)빈단개질적절사솔화흡수계수시,침대반사솔고빈단외연지수함수적지수인자적학정문제,제출채용시역유한차분(FDTD)산법모의우화지수인자적방법,종이보증제취개질절사솔화흡수계수적정학성.해방법근거FDTD산법모의여실측양품시역신호적최소이승차래학정지수인자,당최소이승차취겁소치시소대응적지수인자즉위최우해.포도당다정분말압편적실험표명,채용본문소제출적이용FDTD산법모의우화학정적지수인자위0.495,당용K-K관계구해절사솔화흡수계수시득도적결과경가정학.
Kramers-Kronig can be used to extract refractive index and absorption coefficient of medium in terahertz (THz)region.But it is needed for reflectance to set up an extension function at high frequency.The exponential function is a kind of empirical extension function.In general,the index factor of exponential function is 2 or 4.In this paper,the optimized method used for the algorithm of finite difference time domain (FDTD)is proposed to determinate the index factor.Accuracy of refractive index and absorption coefficient is improved by this method.Determination of index factor is based on least square difference between simulation and measured time domain signals.The index factor corresponds to the minimum of least square difference. Experiment of shows glucose polycrystalline pellet that accuracy of refractive index and absorption coefficient is guaranteed when the optimized index factor is 0.495.This method provides a reference to extract refractive index and absorption coefficient of medium by Kramers-Kronig relation in the THz region.