| 摘要 |
This invention relates to a polarization-independent optoelectronic directional coupler. A wafer (11) e.g. of lithium niobate has light waveguides (13) at its upper surface (12). There are main electrodes (17) and secondary electrodes (18) along the interaction length (L1) of the light waveguides. The wafer is oriented in relation to its crystalline structure (X,Y,Z) such that its optical axis (Z) is in a plane at right angles to the upper surface (12) and contains the longitudinal direction of the waveguides (13). The optical axis (Z) deviates here an angle ( beta ) of at most 15 degrees from the upper surface (12), and the X axis may have six symmetrically distributed positions, of which one is in the plane of the upper surface (12). Independent of the polarization state of a light beam, this beam entering at an input (14) can be switched in its entirety to either of the outputs (15) of the coupler. With the aid of the secondary electrodes (18) an electrical field through the waveguides can be directed at right angles to the upper surface (12). With the stated orientation of the wafer, the refractive index of the material can be changed hereby so that the desired switching is obtained. The light propagation in the direction of the optical axis (Z) permits high pulse frequency. |
