Method of optically connecting an optical fiber sensor to an optical shape sensing console, the optical shape sensing console having a number of single optical channels (C1, C2, C3), the optical fiber sensor having 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 and a fiber sensor connection end for connection to an optical coupler (32; 38) connected to the shape sensing console, the optical coupler (32; 38) having 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) being assigned to the single optical channels (C1, C2, C3), the method comprising the steps: i) connecting the fiber sensor connection end to the optical coupler (32; 38) such that a first fiber core of the fiber cores (A1, A2, A3) is in optical communication with a first optical channel of the optical channels (C1, C2, C3), ii) measuring an optical response of the first fiber core by optically interrogating the first fiber core while a first calibration data set of the calibration data sets is assigned to the first optical channel, iii) identifying the first fiber core among the fiber cores (A1, A2, A3) of the fiber sensor on the basis of the measured optical response of the first fiber core and the calibration data sets of the fiber sensor, and iv) if the first fiber core is identified as not matching with the first calibration data set used in measuring the optical response, then iva) reassigning a second calibration data set of the calibration data sets, which matches with the identified first fiber core, to the first optical channel, or ivb) repositioning the fiber sensor connection end and/or the optical coupler (32; 38) such that a second fiber core matching with the first calibration data set is in optical communication with the first optical channel. i) connecting the fiber sensor connection end to the optical coupler (32; 38) such that a first fiber core of the fiber cores (A1, A2, A3) is in optical communication with a first optical channel of the optical channels (C1, C2, C3), ii) measuring an optical response of the first fiber core by optically interrogating the first fiber core while a first calibration data set of the calibration data sets is assigned to the first optical channel, iii) identifying the first fiber core among the fiber cores (A1, A2, A3) of the fiber sensor on the basis of the measured optical response of the first fiber core and the calibration data sets of the fiber sensor, and iv) if the first fiber core is identified as not matching with the first calibration data set used in measuring the optical response, then iva) reassigning a second calibration data set of the calibration data sets, which matches with the identified first fiber core, to the first optical channel, or ivb) repositioning the fiber sensor connection end and/or the optical coupler (32; 38) such that a second fiber core matching with the first calibration data set is in optical communication with the first optical channel. iva) reassigning a second calibration data set of the calibration data sets, which matches with the identified first fiber core, to the first optical channel, or ivb) repositioning the fiber sensor connection end and/or the optical coupler (32; 38) such that a second fiber core matching with the first calibration data set is in optical communication with the first optical channel.