Tunable bragg grating and devices employing the same

Abstract

The present invention relates generally to electro-optically active waveguide segments, and more particularly to the use of a selective voltage input to control the phase, frequency and/or amplitude of a propagating wave in the waveguide. Particular device structures and methods of manufacturing are described herein.

1. A method for manufacturing an electro-optic waveguide segment having a core and a cladding; the method comprising the steps of:
 forming a Bragg grating in said waveguide segment;    removing a first selective portion of said cladding above at least a portion of said Bragg grating to form a first recess within said cladding, said first selective portion having an outer dimension which is less than an unmodified section of said cladding;    depositing a first electrically conductive material covering at least part of said first selective portion and in direct contact with a deepest portion of said first recess, thereby forming a first electrode, wherein there are substantially no air gaps between said first electrode and said first recess;    removing a second selective portion of said cladding to form a second recess within said cladding, said second selective portion having an outer dimension which is less than an unmodified section of said cladding, said first and second selected portions not contacting one-another;    depositing a second electrically conductive material covering at least part of said second selective portion and in direct contact with a deepest portion of said of said second recess, thereby forming a second electrode, wherein there are substantially no air gaps between said second electrode and said second recess; and    poling said waveguide segment using at least a electric field applied to either said first or second electrode to induce an non-linearity in said waveguide segment.    
     
     
       2. The method recited in  claim 1 , wherein said first recess is substantially filled with said first electrically conductive material. 
     
     
       3. The method recited in  claim 2 , wherein said first electrically conductive material is optically transparent. 
     
     
       4. The method recited in  claim 1 , wherein said second recess is substantially filled with a second electrically conductive material. 
     
     
       5. The method recited in  claim 4 , wherein said second electrically conductive material is optically transparent. 
     
     
       6. The method recited in  claim 1  wherein said poling step is performed using ultraviolet light injected into said waveguide segment in combination with said electric field. 
     
     
       7. The method recited in  claim 1 , wherein said poling step is performed using said electrical field in combination with heating said waveguide segment. 
     
     
       8. A method for manufacturing an electro-optic waveguide segment having a core and a cladding; the method comprising the steps of:
 forming a Bragg grating in said waveguide segment;    removing a first selective portion of said cladding above at least a portion of said Bragg grating to form a first recess within said cladding, said first selective portion having an outer dimension which is less than an unmodified section of said cladding;    depositing a first electrically conductive material covering at least part of said first selective portion and in direct contact with a deepest portion of said first recess, thereby forming a first electrode, wherein there are substantially no air gaps between said first electrode and said first recess;    removing a second selective portion of said cladding to form a second recess within said cladding, said second selective portion having an outer dimension which is less than an unmodified section of said cladding, said first and second selected portions not contacting one-another;    depositing a second electrically conductive material covering at least part of said second selective portion and in direct contact with a deepest portion of said second recess, thereby forming a second electrode, wherein there are substantially no air gaps between said second electrode and said second recess; and    poling said waveguide segment using ultraviolet light injected into said waveguide segment to induce an non-linearity in said waveguide.    
     
     
       9. A method for manufacturing an electro-optic waveguide segment having a core and a cladding; the method comprising the steps of:
 forming a Bragg grating in said waveguide segment; 
 removing a first selective portion of said cladding above at least a portion of said Bragg grating to form a first recess within said cladding, said first selective portion having an outer dimension which is less than an unmodified section of said cladding;  
   depositing a first electrically conductive material covering at least part of said first selective portion and in direct contact with a deepest portion of said first recess, thereby forming a first electrode, wherein there are substantially no air gaps between said first electrode and said first recess; 
 removing a second selective portion of said cladding to form a second recess within said cladding, said second selective portion having an outer dimension which is less than an unmodified section of said cladding, said first and second selected portions not contacting one-another;  
   depositing a second electrically conductive material covering at least part of said second selective portion and in direct contact with a deepest portion of said second recess; and    poling said waveguide segment by heating said waveguide segment in combination with ultraviolet light injected into said waveguide segment to induce an non-linearity in said waveguide segment.    
     
     
       10. A method for manufacturing an electro-optic waveguide segment having a core and a cladding; the method comprising the steps of:
 removing a first selective portion of said cladding to form a first recess within said cladding, said first selective portion having an outer dimension which is less than an unmodified section of said cladding;    removing a second selective portion of said cladding to form a second recess within said cladding, said second selective portion having an outer dimension which is less than an unmodified section of said cladding, said first and second selected portions not contacting one another;    depositing a first electrically conductive material within said first recess and in direct contact with a deepest portion of said first recess, thereby forming a first electrode, wherein there are substantially no air gaps between said first electrode and said first recess;    depositing a second electrically conductive material within said second recess and in direct contact with a deepest portion of said second recess, thereby forming a second electrode, wherein there are substantially no air gaps between said second electrode and said second recess; and    poling said waveguide segment using at least a electric field applied to said first and second selective portions to induce a non-linearity in said waveguide segment.    
     
     
       11. The method for manufacturing recited in  claim 10 , further comprising the step of forming a Bragg grating in said waveguide segment. 
     
     
       12. An optical filter, comprising:
   a first optical fiber comprising a core and a cladding configured to receive a first input light signal comprising a plurality of wavelengths;        a second optical fiber comprising a core and a cladding configured to generate an output light signal;        a first polarization beam - splitter coupled to the first and second optical fibers and configured to convert the first input light signal in the first optical fiber to a first linear polarization state and to convert the first input light signal in the second optical fiber to a second linear polarization state orthogonal to the first linear polarization state;        a first electro - optic waveguide disposed in the first optical fiber, and configured to convert the light signal having the first linear polarization state to a light signal having a circular polarization state having a predetermined handedness;        a second electro - optic waveguide disposed in the second optical fiber, and configured to convert the light signal having the second linear polarization state to a light signal having a circular polarization state having a predetermined handedness; and        a first and a second electro - optic tunable Bragg gratings disposed in the first and second optical fibers, respectively, and configured to reflect selected wavelengths of the light signals having circular polarization states and to reverse the handedness of the circular polarization states, the first and second electro - optic tunable Bragg gratings each comprising:      a first recess within the cladding of its respective optical fiber;        a second recess within the cladding of its respective optical fiber, the first and second recesses not contacting one another;        a first electrically conductive material deposited in the first recess by vapor deposition or sputtering to form a first electrode;        a second electrically conductive material deposited in the second recess by vapor deposition or sputtering to form a second electrode; and        a Bragg grating;          wherein the electro - optic waveguides are configured to receive the light signals having reverse - handedness circular polarization states and to convert the circular polarization states back to orthogonal linear polarization states and thereby generate an output signal, having the selected wavelengths, on the second optical fiber.     
     
     
       13. The filter of  claim 12 , further comprising:
   a second polarization beam - splitter coupled to the first and second optical fibers and configured to receive an input light signal at a selected wavelength in the first optical fiber and to convert the light signal at the selected wavelength to the first linear polarization state in the first optical fiber and to convert the input light signal to the second linear polarization state in the second optical fiber;        a third electro - optic waveguide disposed in the first optical fiber, intermediate the second polarization beam - splitter and the first electro - optic tunable Bragg grating and configured to convert the light signal having the first linear polarization state to a light signal having a circular polarization state; and        a fourth electro - optic waveguide disposed in the second optical fiber intermediate the second polarization beam - splitter and the second electro - optic tunable Bragg grating and configured to convert the light signal having the second linear polarization state to a light signal having a circular polarization state, to thereby add the light signal at the selected wavelength to the input light signal.     
     
     
       14. The filter of  claim 12 , wherein the first and second electro- optical tunable Bragg grating disposed in the first and second optical fibers, respectively, configured to shift a light spectra of light signals passed through the first and second electro - optical tunable Bragg grating, respectively.   
     
     
       15. The filter of  claim 12  wherein the first and second tunable electro- optical electro - optic waveguides are poled electro - optic waveguides.   
     
     
       16. The filter of  claim 12  wherein the first polarization beam- splitter is configured to convert the input light signal to two orthogonal linear polarization states comprising a vertical polarization and a horizontal polarization, respectively.   
     
     
       17. The filter of  claim 12  wherein the input light signal in the first optical fiber is randomly polarized. 
     
     
       18. An optical filtering method, comprising:
   converting a polarization state of a first input light signal to a first linear polarization state in a first optical fiber, the first optical fiber comprising a core and a cladding;        converting the polarization state of the first input light signal to a second linear polarization state being orthogonal to the first linear polarization state in a second optical fiber, the second optical fiber comprising a core and a cladding;        converting the light from the first input signal having the first linear polarization state in the first optical fiber to light from the first input signal having a circular polarization state having a predetermined handedness;        converting the light from the first input signal having the second linear polarization state in the second optical fiber to light from the first input signal having a circular polarization state having a predetermined handedness;        using first and second electro - optical tunable Bragg grating disposed in the first and second optical fibers, respectively, to reflect the light signals of selected wavelengths in the light of the first input signal and to reverse the handedness of the circular polarization states, the first and second electro - optic tunable Bragg grating each comprising:      a first recess within the cladding of its respective optical fiber;        a second recess within the cladding of its respective optical fiber, the first and second recesses not contacting one another;        a first electrically conductive material deposited in the first recess by vapor deposition or sputtering to form a first electrode;        a second electrically conductive material deposited in the second recess by vapor deposition or sputtering to form a second electrode; and        a Bragg grating; and          receiving the light signals having reverse - handedness circular polarization states and converting the circular polarization states back to orthogonal linear polarization states and thereby generating an output signal, having the selected wavelengths, on the second optical fiber.     
     
     
       19. The method of  claim 18 , further comprising
   receiving a second input light signal having an additional selected wavelength;        converting the polarization state of the second light signal at the additional selected wavelength to first and second orthogonal linear polarization states in the first and second optical fibers, respectively, and        converting the light from the second input signal having the first and second orthogonal linear polarization states to light signals having circular polarization states, respectively, to thereby add the light from the second input signal at the additional selected wavelength to the first input light signal.     
     
     
       20. The method of  claim 18 , further comprising using the first and second tunable electro- optical Bragg grating disposed in the first and second optical fibers, respectively, to shift a light spectra of light signals passed through the first and second electro - optical tunable Bragg grating, respectively.   
     
     
       21. The method of  claim 18  wherein converting the polarization state of the first input light signal to the first and second orthogonal linear polarization states is performed by a polarization beamsplitter disposed along the first and second optical fibers. 
     
     
       22. The method of  claim 18  wherein converting the light signals having the two orthogonal linear polarization states in the first and second optical fibers to light signals having circular polarization states is performed by first and second electro- optic waveguides disposed in the first and second optical fibers, respectively.   
     
     
       23. The method of  claim 22  wherein receiving the light signals having reverse- handedness circular polarization states and converting back to orthogonal linear polarization states is performed by the first and second electro - optic waveguides.   
     
     
       24. The method of  claim 22  wherein the first and second electro- optic waveguides are poled electro - optic waveguides.   
     
     
       25. The method of  claim 18  wherein converting the polarization state of the first input light signal to two orthogonal linear polarization states comprises converting a random polarization of the first input light signal to two orthogonal linear polarization states comprising a vertical polarization and a horizontal polarization in first and second optical fibers, respectively. 
     
     
       26. The method of  claim 18  wherein the polarization state of the first input light signal is random polarization and converting the polarization state of the first input light signal to the first linear polarization state in the first optical fiber comprises converting the random polarization state of the first input light signal to the first linear polarization state in the first optical fiber. 
     
     
       27. An optical filtering method, comprising:
   splitting an input light signal having a random polarization into a first light signal having a linear polarized state on a first fiber and a second light signal having a linear polarized state on a second fiber, the first and second light signals having orthogonal linear polarization states;        converting the light signals having the first and second orthogonal linear polarization states to light signals having circular polarization states with a predetermined handedness;        reflecting light signals of selected wavelengths having circular polarization states using a tunable electro - optic Bragg grating to generate reflected light signals having reverse predetermined handedness circular polarization states, the tunable electro - optic Bragg grating comprising:      an optic fiber comprising a core and a cladding;        a first recess within the cladding of the optical fiber;        a second recess within the cladding of the optical fiber, the first and second recesses not contacting one another;        a first electrically conductive material deposited in the first recess by vapor deposition or sputtering to form a first electrode;        a second electrically conductive material deposited in the second recess by vapor deposition or sputtering to form a second electrode; and        a Bragg grating;          converting the reflected light signals of selected wavelengths having reverse predetermined handedness circular polarization states back to orthogonal linear polarization states; and        combining the reflected light signals of selected wavelengths with orthogonal linear polarization states thereby generating an output signal having the selected wavelengths.     
     
     
       28. The method of  claim 27  wherein converting the light signals having the first and second orthogonal linear polarization states to light signals having circular polarization states used a poled electro- optic waveguide.