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Onde evanescenti Near field optics.

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Presentation on theme: "Onde evanescenti Near field optics."— Presentation transcript:

1 Onde evanescenti Near field optics

2 Helmholtz’s equations

3 Plane waves

4 Angular decomposition

5 Angular decomposition

6 Angular decomposition

7 Angular decomposition
It seems impossible to confine light much below l.

8 Angular decomposition
However it is simple to confine light much below l.

9 Plane waves

10 Plane waves Evanescent waves

11 SNOM Angular decomposition Fields localized below l need
evanescent waves SNOM

12 Riflessione totale

13 Metodo grafico per rifrazione

14 Metodo grafico per rifrazione

15 Metodo grafico per rifrazione
Angolo limite

16 Metodo grafico per rifrazione
Oltre angolo limite

17 Rifrazione oltre angolo limite

18 Rifrazione oltre angolo limite

19 Rifrazione oltre angolo limite

20 Onda evanescente

21 Relazioni di Fresnel Ei Er y Et Ht qt Hi Hr z n2

22 Relazioni di Fresnel Ei Er y Et Ht qt Hi Hr z n2

23 Riflessione e rifrazione
Ei Er y Et Ht qt Hi Hr z n2

24 Riflessione e rifrazione

25 Riflessione totale

26 Riflessione totale

27 The Nobel Prize in Physics 2009
Charles K. Kao "for groundbreaking achievements concerning the transmission of light in fibers for optical communication"

28

29 Onda evanescente Contiene energia elettromagnetica?

30 Onda evanescente Atomo, molecola, centro di scatterning

31 Onda evanescente Atomo, molecola, centro di scatterning
EMISSIONE RIEMESSA Atomo, molecola, centro di scatterning Si puo’ assorbire energia da un’onda evanescente

32 Frustrated total internal reflection
Si puo’ “trasformare” un’onda evanescente in un’onda propagante Simile all’effetto tunnel in MQ

33 Frustrated total internal reflection
Si puo’ “trasformare” un’onda evanescente in un’onda propagante Simile all’effetto tunnel in MQ

34 Relazioni di Fresnel TE TM

35 Vettore di Poynting

36 Relazioni di Fresnel TE TM

37 Onda evanescente

38 Bilancio energia ?

39 Goos Hanchen shift

40 Goos Hanchen shift D

41 Goos Hanchen shift

42 Misura del Goos Hanchen shift
Frustrated total attenuated reflection

43 Misura del Goos Hanchen shift
l=32.8 mm A. Haibel et al. Phys. Rev. E 63, (2001)

44 Misura del Goos Hanchen shift
l=32.8 mm A. Haibel et al. Phys. Rev. E 63, (2001)

45 Modi guidati

46 Dielectric slab Within the limit angle Beyond the limit angle Cono di
luce Beyond the limit angle

47 Dielectric slab evanescent waves Slab evanescent waves

48 Beyond the limit angle In the media In air

49 Even states Odd states Dielectric slab Beyond the limit angle Cono di
luce Even states Odd states

50 Beyond the limit angle

51 Evanescent fields Extended modes Guided modes

52 Analogy with QWell Extended states Confined states Modi guidati
Cono di luce Energy E/V Modi guidati z Confinamento moto lungo z Evanescent wavefunction

53 Total internal reflection Excitation of the guided modes
evanescent waves

54 Excitation of the guided modes
Frustrated Total internal reflection


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