Evanescent waves and reflection from metals, Lecture notes of Physics

Evanescent waves. Reflection from metals.

Typology: Lecture notes

2025/2026

Available from 06/06/2026

mahesh-kumar-meher
mahesh-kumar-meher 🇮🇳

6 documents

1 / 6

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
pf3
pf4
pf5

Partial preview of the text

Download Evanescent waves and reflection from metals and more Lecture notes Physics in PDF only on Docsity!

Evanescent Waves @) When tolad infornal reflection (TR) oecurs, We assume thal none of the bight is tomemilted. Let us try t6 understand thir. * Transmilled wave : [ey = ee of RP) i) For the case shoum in the left: | 7 A a “a “ Ke (-sine, x - cas 0,2) . (2% +yyt 23) ky (-* Sin — Zcos 8, ) x NN a aT. vf u Os wv XQ Ww n Sin By = $in® he a ee Using Snell's lan: oe = Cos &=\\-sin - 4) - sido .-l Tn lhe ease of TIR, 6>0, DP O> sin fr) - > sine 77n > size rm ) sine >| aed > Lr SB lzl, =. d . s, A= 500mm, @= 60°, ealerate jel, ‘ . When Ne\S I, = 200 nm x ou Syo00 times thinrer \ © an Jaleo _, = OBO | than Querage Auman hair } ds)* / Examples : wo (cross alk) sh is not strictly corbin te cove. \. Fiber optic» Evanescont ated moxt & one anoth another, which Causes Crost talk. 2. Near freld seanrmng optical microscopy: A Deere fiber be goes close to the coe ae /sample before the avanescent wale dies, the ec ote cateh tt. Since the tp & cub - wawetongth , it heals the deffcackion -\mated yeso lien: Reading hiraornec : 1. Surface asmon veconance ; 2. Dirzck onal couples im integrated photonics. wave extends te cladding. Tf. coves fe fibers are er, evanescent Waves may Leak irite wave Solution, for @ A m, assume a wail | “ae uae a : gk. oa es Fond, A singpe component : Es the “Wave egal is: QE 5 ae o OE, 12 e Je t 2+ 32” = €,c™ 3t c 3t L wave in Re differenti Substiliting “te eae ie “2 E, e equalion » ee wt) - : i (2.2 -ct) —— (- iw) Be E, (-ke-Ky- ker) & a - ek (-w*) Ee c* 2 oC - wr 2 es w n~ y u OVE NL e Ls 4 | NEU : ke 2 qi hs | earlier that when K fs complex, (hare cont wares sation) . Seon a = altzrualion (evanes Ps the rePrackive index , ; ; “ e cs < ar = —kK Wei pd wr? Grd) > W oO 2) n= I+ e1) nas \ Since the refractive index 6 & complex number, N= Ne + Nz add apn Ce) Coan) ©) Sy n,4un Lit, 2 ea R L [+2 Ew oo : a Sauaning fatima) = (FY Gos 2 2 ‘ ; = Ng-Ny + 2iNg Nr = l+* Bo Com pooing veal and complex a na- “r=! oe ee qe “The clechic field : E= E, ae, St K is along 2 direckon, we am wrle K-¥ = kz@= 2a . 1, roe y . Ex an avbihary diveclio , voprecenling, distance ‘travelled by On distance ;S", Wwe cam wrile KY > Ks : oe jlks <0!) i) -f 2 (nptin : E, él rll Sg ix)s - wt] 5 ae 2 Ke =(ngti7 ce : 6 clk 1) = E, o* 7 olka VT — ve ravels wilh altenualion wa aed by te velocity B= Ine ’ wt defined by veal part ie abtobed dlelermines role of abso The umaginanny por, nz Is therefore called aa exlincbon Cobfficiert. em. tb pele Curent 3. of is bp educleg