Fiber Optic Diffraction Grating

Abstract

The present invention is directed to an optical fiber grating having a core, that is capable of controlling the light signal transmission therethrough by causing at least one of: at least one spectral peak, and/or at least one spectral dip in its core light transmission spectrum, corresponding to at least one predetermined wavelength. The inventive optical fiber diffraction grating comprises at least one longitudinally positioned structural element of a predetermined geometric profile and that is configured for diffracting a portion of the transmitted light signal at at least one predefined wavelength thereof, from at least one core mode into at least one of: at least one cladding mode and/or at least one radiating mode. Various embodiments of a number of novel techniques for fabrication of the inventive optical fiber diffraction grating are provided, inclusive of a novel technique for fabricating the inventive grating from a single material. Advantageously, such novel fabrication techniques rely on configuration of a desired geometric profile for the at least one structural element portion of the novel grating, each profile comprising a number of readily configurable parameters that can be selected and/or adjusted during fabrication, to produce a variety of novel fiber diffraction gratings, each having a corresponding specific desirable core transmission spectrum having at least one of: least one spectral peak, and/or at least one spectral dip therein, corresponding to at least one specific desired wavelength, dependent on the configuration of the applicable geometric profile.

1 . A fiber diffraction grating for controlling a light signal transmission of a predetermined at least one wavelength therethrough, comprising:
 a modified optical fiber having at least one core mode, and at least one of: at least one cladding mode and at least one radiating mode, said modified optical fiber further comprising:
 at least one structural element having a predetermined geometrical profile, wherein said predetermined geometrical profile is configured to diffract a light signal of said at least one core mode at at least one diffracted wavelength, selected from the at least one predetermined wavelength. 
   
     
     
         2 . The fiber diffraction grating of  claim 1 , wherein said predetermined geometrical profile comprises a predetermined helical pitch, a predetermined helical diameter, and a single predetermined handedness. 
     
     
         3 . The fiber diffraction grating of  claim 2 , wherein said predetermined pitch and said predetermined diameter are further configured to couple light into at least one of said at least one radiating mode. 
     
     
         4 . The fiber diffraction grating of  claim 2 , wherein said predetermined pitch and said predetermined diameter are further configured to couple into at least one of said at least one cladding mode. 
     
     
         5 . The fiber diffraction grating of  claim 2 , wherein the light signal transmission comprises a core transmission spectrum, representative of the light signal transmitted in said at least one core mode, and wherein said predetermined pitch and said predetermined diameter are further configured to produce at least one of: a spectral dip or a spectral peak in said core transmission spectrum. 
     
     
         6 . The fiber diffraction grating of  claim 2 , wherein said modified optical fiber comprises a microstructured optical fiber that has been twisted, in accordance with a predefined twist profile, to produce therein said at least one structural element of said predetermined helical pitch and said predetermined helical diameter. 
     
     
         7 . The fiber diffraction grating of  claim 1 , wherein the light signal transmission comprises a core transmission spectrum, representative of the light signal transmitted in said at least one core mode, and wherein said modified optical fiber comprises a microstructured optical fiber having at least one predefined distortion in lateral periodicity therein that is configured to produce at least one predefined defect state, each causing a corresponding at least one spectral dip in said core transmission spectrum. 
     
     
         8 . The fiber diffraction grating of  claim 1 , wherein said at least one structural element comprises a plurality of longitudinal channels defined within said modified optical fiber, and sized and positioned in accordance with a first predetermined pattern. 
     
     
         9 . The fiber diffraction grating of  claim 8 , wherein at least a portion of said plural longitudinal channels are filled with one of: vacuum, air, a predetermined gaseous substance, or a predetermined dielectric material. 
     
     
         10 . The fiber diffraction grating of  claim 1 , wherein said at least one structural element comprises a plurality of longitudinal grooves defined in said modified optical fiber, and sized and positioned in accordance with a first predetermined pattern. 
     
     
         11 . The fiber diffraction grating of  claim 10 , wherein at least a portion of said plural longitudinal grooves are filled with one of: air, or a predetermined dielectric material.