High power optical fiber ends having partially-doped gratings
View Patent ↗A system and method for creating a robust anti-reflective surface on a fiber end using various etching techniques to create a shallow grating that creates an effective index of refraction region to transition from air or the input material to the material of the fiber optical cable.
1. An anti-reflective (AR) optical end cap comprising a shallow anti-reflective uniform grating pattern formed on a portion of an input surface,
wherein (i) the end cap is formed of a glass material, (ii) the grating has a depth, and (iii) only a top 10%-60% of the depth of the grating is doped.
2. The optical end cap of claim 1 , wherein the depth is in a range of about 20% to about 40% of a desired input wavelength.
3. The optical end cap of claim 1 , wherein the grating pattern comprises substantially parallel lines etched into the optical end cap.
4. The optical end cap of claim 3 , wherein the lines are formed at a repeating distance from each other.
5. The optical end cap of claim 4 , wherein the distance between two consecutive parallel lines is in the range of about 50 nm to about 1000 nm.
6. The optical end cap of claim 3 , wherein the width of lines ranges from about 1/10 of a micron to about ⅕ of a micron.
7. An anti-reflective (AR) fiber optical cable end comprising a shallow anti-reflective grating pattern,
wherein (i) the grating has a depth, and (ii) only a top 10%-60% of the depth of the grating is doped.
8. The grating pattern cable end of claim 7 , wherein the depth is in a range of about 20% to about 40% of a desired input wavelength.
9. The cable end of claim 8 , wherein the variation in the distance between two consecutive parallel lines is in the range of about 50 nm to about 1000 nm.
10. The cable end of claim 8 , wherein the variation in the distance is in the range of about 50 nm to about 100 nm over a first region of the grating and in the range of about 200 nm to about 400 nm over a second region of the grating.
11. The cable end of claim 7 , wherein the grating pattern comprises substantially parallel lines etched into the fiber optical cable end.
12. The cable end of claim 11 , wherein the lines are formed at varying distances from each other.
13. The cable end of claim 11 , wherein the width of lines ranges from about 1/10 of a micron to about ⅕ of a micron.
14. A method for producing an anti-reflective (AR) end on an optical fiber cable comprising the steps of:
determining at least one dimension of a plurality of channels to be formed based on a desired wavelength(s) input;
forming the channels using one of:
laser interference lithography, reactive ion etching, wet etching, dry etching, ion deposition, or chemical deposition, wherein the channels form a grating having a depth; and
doping only a top 10%-60% of the depth of the grating.
15. The method of claim 14 , wherein the doping step comprises diffusing a dopant into a percentage of the depth of the channels.
16. The method of claim 14 , wherein the dimension is selected from a list consisting of number of channels, depth of channels, angle of channels, and spacing of the channels.
17. A method for producing an anti-reflective (AR) end on a fiber optical cable comprising the steps of:
determining at least one dimension of a plurality of channels to be formed based on a desired wavelength(s) input;
forming the channels on an end cap, wherein the channels form a grating having a depth;
doping only a top 10%-60% of the depth of the grating; and
attaching the etched end cap to an end of a fiber optical cable.
18. The method of claim 17 , wherein the end cap is a quartz block.
19. The method of claim 17 , wherein the attaching step is a splicing technique.