BIPOLAR TUNING OF SILICA-ON-SILICON DIRECTIONAL-COUPLERS BY ELECTRON-BEAM IRRADIATION

It is demonstrated that the coupling strength of buried channel waveguide silica-on-silicon directional couplers may be tuned by flood irradiation with an electron beam. Experimental data are presented for devices with arsenosilicate glass cores and pure silica cladding. It is shown that the change in coupling strength may be positive or negative as desired, depending on the energy of the electron beam, due to differences in irradiation sensitivity between the core and cladding materials.