光电子学作业(第12章).docVIP

第一章 1.2 Refractive index (a) Consider light of free-space wavelength 1300 nm traveling in pure silica medium. Calculate the phase velocity and group velocity of light in this medium. Is the group velocity ever greater than the phase velocity? (b) What is the Brewster angle(the polarization angle qp) and the critical angle(qc) for total internal reflection when the light wave traveling in this silica medium is incident on a silica/air interface. What happens at the polarization angle? (c) What is the reflection coefficient and reflectance at normal incidence when the light beam traveling in the silica medium is incident on a silica/air interface? (d) What is the reflection coefficient and reflectance at normal incidence when a light beam traveling in air is incident on an air/silica interface? How do these compare with part (c) and what is your conclusion? 1.5 Reflection at glass-glass and air-glass interface A ray of light that is traveling in a glass medium of refractive index n1=1.460 becomes incident on a less dense glass medium of refractive index n2=1.430. Suppose that the free space wavelength of the light ray is 850 nm. (a) What should the minimum incidence angle for TIR be? (b) What is the phase change in the reflected wave when the angle of incidence qi =85 ?and when hqi =90 ?? (c) What is the penetration depth of the evanescent wave into medium 2 when eqi =85 ?and when aqi =90 ?? (d) What is the reflection coefficient and reflection at normal incidence (nqi =0 ?)when the light beam traveling in the silica medium (n=1.455) is incident on a silica/air interface? (e) What is the reflection coefficient and reflectance at normal incidence when a light beam traveling in air is incident on an air/silica interface (n=1.455)? How do these compare with part (d) and what is your conclusion? 1.6 TIR and polarization at water-air interface (选作) (1) Given that the refractive index of water is about 1.33, what is the polarization angle for light traveling in ai