An exemplary embodiment of the disclosure provides a double fiber optic mode adapter including: a fiber core having a variable core diameter; a fiber cladding having a variable cladding size; a first input interface corresponding to a first core diameter and a first cladding size; a second input interface corresponding to a second core diameter and a second cladding size; a thermally-tapered region wherein the variable core diameter of the fiber core transitions from the first core diameter to the second core diameter and the variable cladding size of the fiber cladding transitions from the first cladding size to a third cladding size; and an etched tapered region wherein the variable core diameter of the fiber core is constant and the variable cladding size of the fiber cladding transitions from the third cladding size to the second cladding size.