A new fabrication method of a star coupler has been described. It is fabricated by stacking polymer films and then sticking them by a heat press. Using this method, the star coupler can be produced very easily and has square core cross sections. The 5-port multimode star coupler made on an experimental basis has an output power variation of 0.9 dB and an insertion loss of 3 dB.

Light intensity variation is performed in a multilayer optical circuit element consisting of stacked crossing thin film optical waveguides. The principle of operation is the interference of two guided light waves coupled with each other at the intersection of the waveguide of the optical circuit element. Measurements are carried out for each case of the coupling coefficient of the optical circuit element equal to 3 dB and not equal to 3 dB. The percentage variation obtained is 45%.