Microfabrication technique for structuring non-planar electromagnetic waveguides
A method for manufacturing a multifunctional electromagnetic waveguide from a tapered optical fiber is provided. The method involves mounting the optical fiber on a roto-translational handling apparatus, forming a first mask on a tapered section of the optical fiber to define a shape of an optical window, forming a first metal layer around the tapered section leaving a lateral edge of the first mask uncovered, removing the first mask by chemical etching to uncover the optical window, depositing a first transparent layer around the tapered section, depositing a second metal layer around the first transparent layer, forming a second mask that defines a shape of a conductive track, removing the second metal layer by chemical etching, and removing the second mask by chemical etching to uncover the conductive track.
1 . A method for manufacturing a multifunctional electromagnetic waveguide from a tapered optical fiber, the method comprising:
mounting the optical fiber on a handling apparatus which may be actuated to translationally move the optical fiber along at least one translation axis and rotate the optical fiber about a longitudinal axis thereof,
submerging a tapered section of the optical fiber in a photoresist and subjecting the photoresist to two-photon polymerization to form a first mask defining a shape of at least one optical window,
subjecting the masked tapered section to a plurality of directional flows of metal material to form a first metal layer around the tapered section, leaving at least one lateral edge of the first mask uncovered,
removing the first mask by chemical etching in such a way to uncover said at least one optical window,
depositing a transparent, conformal first layer around the tapered section, said transparent, conformal first layer being made of insulating material,
depositing a second metal layer around the insulating transparent, conformal first layer,
submerging the tapered section in the photoresist and subjecting the photoresist to two-photon polymerization to form, at the tapered section, a second mask defining a shape of at least one conductive track,
removing, by chemical etching, the second metal layer where the second metal layer is not covered by the second mask, and
removing the second mask by chemical etching in such a way to uncover said at least one conductive track.
2 . The method of claim 1 , further comprising depositing a transparent, conformal second layer around the tapered section, said transparent, conformal second layer being made of polymer or semiconductor material.
3 . The method of claim 2 , further comprising
forming at least one recess at at least one measurement pad of said at least one conductive track, and
depositing a third metal layer in said at least one recess.
4 . The method claim 1 , further comprising
mounting the multifunctional electromagnetic waveguide on a printed circuit interface, said printed circuit interface comprising
a first seat configured to receive the multifunctional electromagnetic waveguide,
a second seat aligned with the first seat and configured to receive an optical cable connected to the multifunctional electromagnetic waveguide, and at least one conductive track comprising a distal connection pad facing the first seat and configured to be welded to a relevant connection pad of said at least one conductive track of the multifunctional electromagnetic waveguide.
5 . The method of claim 1 , wherein, during the two-photon polymerization, the optical fiber is rotated around its longitudinal axis by the handling apparatus.