Question

i'm not sure which equations to use so i would appreciate any help! thanks

1. Let us consider that the light field propagate through the dielectric and impinges on a dielectric-air interface. Obtain the localization length 1 (1/e decay length) for an evanescent wave excited by a laser beam with wavelength 850 nm at an angle of incidence 0i = 80° for a planar Si3N4 interface characterized by refractive index n = 2. For concreteness, let us define the localization length le at which the "intensity" of the light field is localized by 1/e of its peak intensity (note that in class, we have loosely called the localization length as the field decay, instead of the decay of the intensity) - Points: 1

Answer 1

Sol x = 850nm Given S we have n=2 ; and n'=l localization 0;=80° for air length I le: . I n2 sino n12 850 nm 2x3.14 (2) ² (sin 80) ²_1² 850nm 6.28 Jaxco.984833-1 8 SO 8 so - 6,28 x√3,879-1 850 - 850 — 6:28 5 2,8793 S SO = '79. 8 na 6.28 x 1,6969 Evanscent wave Localization is given length by of a Given 1 l = 79.8 mm