The refractive index of dielectrics is a function of the density, temperature, and the wavelength of the incident light. The refractive index and material dispersion are determined by the plasma and the resonance frequencies. Physically, the forced oscillation of an induced dipole is driven by the light wave, vibrating in the plane perpendicular to the propagation direction of light. The incident light is absorbed at the resonance frequency. In this case, the induced dipole is transformed into independent neutral oscillator (atom). Yet, the forced oscillation of the dipole and the thermal motion of the atom have different vibration modes. Each mode carries out thermal energy. The incident light should overcome the thermal energy to excite the vibration modes of the dipoles. These features lead to the temperature-dependent plasma and resonance frequencies, and consequently yield the temperature-dependent refractive index and material dispersion. Moreover, the change of refractive index with temperature is found to relate with specific heat capacity. The proposed approach is applied for analyzing the refractive index of silica glass.

电介质的折射率是密度、温度和入射光波长的函数。折射率和材料色散由等离子体和共振频率决定。在物理上，感应偶极子的受迫振荡由光波驱动，在垂直于光传播方向的平面内振动。入射光在共振频率处被吸收。在这种情况下，感应偶极子转化为独立的中性振荡器（原子）。然而，偶极子的受迫振荡和原子的热运动具有不同的振动模式。每种模式都进行热能。入射光应克服热能以激发偶极子的振动模式。这些特征导致依赖于温度的等离子体和共振频率，从而产生依赖于温度的折射率和材料色散。此外，发现折射率随温度的变化与比热容有关。所提出的方法用于分析石英玻璃的折射率。