The present invention relates to a method of and a system for optically connecting an optical fiber sensor (12) to an optical shape sensing console (21). The optical shape sensing console (21) has a number of single optical channels (C1, C2, C3). The optical fiber sensor (12) has a number of single fiber cores (A1, A2, A3) angularly spaced with respect to one another around a longitudinal center axis of the fiber sensor (12) and a fiber sensor connection end (30) for connection to an optical coupler (32； 38) connected to the shape sensing console (21). The optical coupler (32； 38) has the optical channels (C1, C2, C3) arranged for optical connection with the fiber cores (A1, A2, A3). A number of single calibration data sets indicative of individual optical properties of the single fiber cores (A1, A2, A3) is assigned to the single optical channels (C1, C2, C3). The fiber sensor connection end (30) is connected to the optical coupler (32； 38) such that a first fiber core (A2) of the fiber cores (A1, A2, A3) is in optical communication with a first optical channel (C1) of the optical channels (C1, C2, C3). An optical response of the first fiber core (A2) is measured by optically interrogating the first fiber core (A2) while a first calibration data set of the calibration data sets is assigned to the first optical channel (C1). The first fiber core (A2) is identified among the fiber cores (A1, A2, A3) of the fiber sensor (12) on the basis of the measured optical response of the first fiber core (A2) and the calibration data sets of the fiber sensor (12). If the first fiber core (A2) is identified as not matching with the first calibration data set used hi measuring the optical response, then a second calibration data set of the calibration data sets, which matches with the identified first fiber core (A2), is reassigned to the first optical channel (C1), or the fiber sensor connection end (30) and/or the optical coupler (32； 38) are repositioned such that a second fibe
