Method for the fabrication of optical waveguide devices in photonic crystal fibers and in waveguides with hollow structures
There is provided a method to fabricate optical taps and waveguide devices in photonic crystal fibers and other fibers with hollow structures. The method involves a preparation step, where the hollow holes inside the fiber are collapsed or partially modified locally; and a waveguide fabrication step, where a femtosecond laser is focused inside the fiber and used to produce optical waveguides that interact in the region that was previously modified in the preparation step.
1. A method for making a femtosecond laser fabricated waveguide to couple light from a core of a photonic crystal fiber to a cladding of the photonic crystal fiber, the method comprising the steps of:
a preparation step in which the photonic crystal fiber is heated in a localized region to modify a region of the core within the localized region; and
a waveguide fabrication step in which a femtosecond laser is focused inside the photonic crystal fiber in order to define a waveguide that interacts with the modified core region;
wherein the preparation step modifies the region by producing a partial or complete collapse of a hollow structure surrounding the core within the localized region.
2. The method of claim 1 wherein the preparation step uses electrical arc discharge to heat the localized region.
3. The method of claim 1 wherein the preparation step uses laser radiation to heat the localized region.
4. The method of claim 1 wherein the cladding of the hollow structure of the photonic crystal fiber surrounding the core has one or more radii that is larger than the diameter core.