Waveguide for efficient light trapping and absorption

摘要

A waveguide is provided on which an electromagnetic wave impinges, the electromagnetic wave having a wavelength λ included in a given interval Δλ of interest centered on a λcentr. The waveguide comprises a film defining a surface on a plane on which the electromagnetic waves are apt to impinge, having a thickness in a direction substantially perpendicular to the surface, the film being realized in a material having a first refractive index; a plurality of scatterers being randomly distributed in two directions in at least a portion of the surface of the film, the scatterers having a substantially constant cross section along said substantially perpendicular direction. The scatterers are realized in a material having a second refractive index lower than the first refractive index, wherein the wavelength of the incident electromagnetic waves is comprised between;0.1<Δλλcentr≤3
and the area of the cross section of said scatterers is between
;π·(Φref/6)2≤Ascatt≤π·Φref2⁢⁢where⁢⁢Φref=nscattnfilm·λcentr.

主权项

1. A waveguide (10) on which an electromagnetic wave impinges, said electromagnetic wave having a wavelength λ included in a given interval Δλ of interest centered on a λcentr, said waveguide comprising:
a film defining a surface on a plane (X,Y) on which said electromagnetic waves are apt to impinge, and having a thickness in a direction (Z) substantially perpendicular to said surface, said film being realized in a material having a first refractive index (nfilm); a plurality of scatterers (11), said scatterers being randomly distributed in two directions in at least a portion of said surface of said film, said scatterers having a substantially constant cross section along said substantially perpendicular direction (Z); said scatterers being realized in a material having a second refractive index (nscatt), said second refractive index being lower than said first refractive index (nfilm); wherein the wavelength of the incident electromagnetic waves is comprised between0.1<Δλλcentr≤3and wherein the area (Ascatt) of the cross section of said scatterers is comprised between π·(Φref/6)2≦Ascatt≦π·Φref2, whereΦref=nscattnfilm·λcentr.