Lensed optical fiber taper and methods of manufacturing same
There is described a method of manufacturing a lensed optical fiber using an optical fiber having a tapered region decreasing in diameter along a longitudinal direction leading to a taper tip. The method generally has: while the tapered region and the taper tip of the optical fiber are immersed into an etching liquid, heating the etching liquid surrounding the taper tip in accordance with a temperature gradient in which temperature increases longitudinally from the tapered region to the taper tip, said the local heating causing a corresponding etching rate gradient shaping the taper tip into a lens.
1 . A method of manufacturing a lensed optical fiber using an optical fiber having a tapered region decreasing in diameter along a longitudinal direction leading to a taper tip, the method comprising:
while the tapered region and the taper tip of the optical fiber are immersed into an etching liquid, heating the etching liquid surrounding the taper tip in accordance with a temperature gradient in which temperature increases longitudinally from the tapered region to the taper tip, said heating causing a corresponding etching rate gradient shaping the taper tip into a lens.
2 . The method of claim 1 wherein the etching liquid absorbs light within an absorption spectral range, said heating being performed using a laser beam having optical energy distributed at least partially in the absorption spectral range of the etching liquid.
3 . The method of claim 2 wherein heating includes injecting the laser beam within the optical fiber, and propagating the laser beam along the longitudinal orientation towards the taper tip.
4 . The method of claim 2 further increasing a laser power of the laser beam over a given laser power threshold, the laser power threshold being associated to at least one of an etched taper angle and an etched tip radius.
5 . The method of claim 2 wherein the etching liquid includes hydrofluoric acid and the laser beam is a near-infrared laser beam.
6 . The method of claim 1 wherein the lens has an etched taper angle below about 10 degrees and an etched tip radius below about 10 microns.
7 . The method of claim 1 wherein said etching includes rounding the taper tip to form a rounded tip.
8 . The method of claim 7 wherein the rounded tip is one of hemispherical, parabolic and hyperbolic in shape.
9 . The method of claim 1 wherein the tapered region has in succession at least a first tapered region, a second tapered region extending from the first tapered region, and the taper tip, said heating including heating at least the second tapered region and the taper tip.
10 . The method of claim 9 wherein said first tapered region has a greater taper angle than a taper angle of the second tapered region.
11 . A method of manufacturing a lensed optical fiber, the method comprising: providing an optical fiber having a tapered region decreasing in diameter along a longitudinal direction and leading to a taper tip; and while the tapered region and the taper tip of the optical fiber are immersed into an etching liquid, heating the etching liquid surrounding the taper tip in accordance with a temperature gradient in which temperature increases longitudinally from the tapered region to the taper tip.