Coupling device for coupling hollow-core optical fibres comprising a coupling element

A device (D) for coupling optical fibers, comprising:

• a first coupling-inhibited hollow-core optical fiber (FO1) comprising a first microstructured cladding (SCF1) comprising a plurality of first confining tubular features (MCF1) having a first thickness, called the confining thickness tcf1, said features being distributed in a ring and encircling, at least partially, a first core (C1) so as to confine at least radiation at a wavelength λop to said first core,
• a second coupling-inhibited hollow-core optical fiber (FO2) comprising a second microstructured cladding (SCF2) comprising a plurality of second confining tubular features (MCF2) having a second thickness, called the confining thickness tcf2, said features being distributed in a ring and encircling, at least partially, a second core (C2) so as to confine said light radiation to said second core,
• a coupling element (SCP) arranged between the first and second cores, said coupling element comprising at least one coupling tubular feature (MCP, MCP1, MCP2, MTa) comprised at least partially in said first microstructured cladding and/or said second microstructured cladding and having a wall thickness tcp called the coupling thickness and a material index ncp called the coupling index, said coupling thickness tcp being different from said first and second confining thicknesses tcf1, tcf2,
• an arrangement of the coupling element, the coupling thickness tcp and the coupling index ncp being configured depending on said wavelength λop so as to create a leakage channel at said wavelength λop allowing the radiation guided by the first optical fiber to be coupled to the second optical fiber and/or the radiation guided by the second optical fiber to be coupled to the first optical fiber.