文档介绍：凝聚态光物理学
第1页，共14页，2022年，5月20日，9点0分，星期一
引言:光学过程的分类，光学系数，复折射率与复介电常数，光学材料(绝缘晶体，半导体，玻璃，金属，高分子材料等)，凝聚态物质光学性质的特征(对称性，电子能带 = N S
Rayleigh scattering :
第4页，共14页，2022年，5月20日，9点0分，星期一
The complex refractive index and dielectric constant
Complex refractive index
: extinction coefficient
Where
Complex dielectric constant
The relationship between the real and imaginary
parts of two coefficients:
For weakly absorbing medium, is very small,
The reflectivity (normal incidence) :
In the transparent region of material :
is very small, and 2 are negligible, one may consider only the real parts of n and ;
In the absorption region, one need to know
both the real and imaginary parts of n and .
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Optical materials
Crystalline insulators and semiconductors
Transparency range, the index
may be taken to be real with no
imaginary component
(approximately constant n=)
R = , hence T =(1-R)2=
Phonon absorption or lattice
absorption
Due to absorption by bound
electrons
Fundamental absorption edge,
is determined by the band gap.
The optical properties of semiconductors are similar to
those of insulators, expect that the electronic and phonic
transitions occur at longer wavelengths. Its transparency
range lies outside the visible spectrum, so it has a dark
Metallic appearance.
第6页，共14页，2022年，5月20日，9点0分，星期一
Optical materials
Crystalline insulators and semiconductors
Materials can take on new properties by controlled doping with optically active substance.
Transmission spectrum of ruby (ruby Al2O3
With % Cr3+) compared to sapphire(pure
Al2O3). The thicknesses of the two crystals
were mm and mm, respectively
The principle of doping optically active atoms
into colourless hosts is employed extensively
in the crystals used for solid state lasers. A
typical example is the ruby crystal. Rubies
consist of Cr+3 ions doped