Integrated Electro-Optical E-Field Sensor Based on Directional Coupler

Optical bias is a key factor in the behavior of integrated optical E-field sensors. The directional coupler based waveguide structure can produce a better bias, but yielding a complicated transfer function simultaneously. An improved design based on directional coupler is demonstrated in this paper and the waveguide was fabricated by appealing proton-exchange. This kind of sensor has a sinusoidal transfer function which is more applicable than the conventional one. The calibration results show that the optical biases of the resulting devices are deviating the ideal operating point 3.3°, 7.9°, and 14.5° separately, which verifies that this improved design can ameliorate the bias effectively.