High-performance unidirectional electrooptic modulator based on polymeric highly multi-mode waveguides

A unidirectional electrooptic modulator based on an asymmetrical highly mul ti-mode waveguide coupler is proposed. Firstly, the energy distributions of all the modes within two highly multi-mode waveguides are analyzed with ei genstate theory. Then, to achieve high switching performance in a guided-wa ve coupler, a dumping wall is placed on the larger waveguide of an asymmetr ic pair of waveguides, so that the larger waveguide has a dumping effect. T his dumping effect makes the asymmetric highly multi-mode waveguide coupler possess a highly efficient unidirectional coupling process. Due to the lar ge cross-section of the waveguide, a new modulation electrode structure is built. Based on this dumping effect, the unidirectional coupling process is theoretically modeled. Furthermore, in both scenarios, i.e., the unmodulat ed state and the electrooptically modulated state, the unidirectional coupl ing efficiencies are studied. As a result, not only can a high unidirection al coupling efficiency of 100% be achieved, but a high electrooptic modulat ion depth more than 90% can also be implemented in theory, and a high therm ooptic modulation depth more than 90% under a low modulation voltage of 30 volts is also experimentally achieved. This device can be used for multi-mo de optical interconnection systems such as data communication and fiber sen sor networks. (C) 1999 Elsevier Science Ltd. All rights reserved.