Patent ID: 6271968
Filing Date: 2001-08-07
Classification: G02B

Abstract:
An optical filter with a sharp cut-off at a predetermined wavelength .lambda., comprising:a pair of optical media respectively defining an inlet port and an outlet port and having an inclined interface such that a light beam passing between said inlet and outlet ports strikes said interface at a non-normal angle of incidence .alpha.;a functional core comprising at least one material sandwiched between said optical media at said interface, said functional core having a complex refractive index of the form n-ik, wherein n and k are optical constants, n being the real refractive index, k being the extinction coefficient, and wherein the real refractive index n is highly dispersive in one wavelength region, and the extinction coefficient k is highly dispersive in another wavelength region adjacent said one wavelength region, said extinction coefficient having a high value on the cut-off side of said predetermined wavelength; andwherein said angle of incidence .alpha. is selected such that light at said predetermined wavelength strikes said interface at a critical angle whereby total internal reflection at said predetermined wavelength occurs in said functional core and on the cut-off side of said predetermined wavelength transmission is inhibited by a high value of said extinction coefficient.