A LiNbO3 Linear Intense Electromagnetic Pulse (EMP) Sensor by Using Incident Lightwave Near Optical Axis

In order to measure the time-domain waveform of the intensive electromagnetic pulse (EMP), a reflective LiNbO₃ (LN) trapezoidal crystal intensive electric field sensor is designed and developed. By designing the size of the right-angle trapezoid LN crystal and setting the hypotenuse of the crystal parallel to the light transmission direction, a static operating point of π/2 is obtained, so that the sensor can work in the near-linear region. As the 1/8 wave plate is avoided, the device structure is simplified. The results show that when the right-angle side, upper and lower bottom sides of the designed right-angle trapezoid LN are 42.2 mm, 1.5 mm, and 3.3 mm respectively, the static operating point of the sensor is 77.4°. The sensor can measure the μs and ns level EMP in the time-domain without distortion. The minimum and maximum measurable pulsed electric fields are 9.7 kV/m and 324.8 kV/m respectively. When the spectrum analyzer resolution bandwidth (RBW) is 10 Hz, the minimum measurable electric field of the sensor is 1.26 V/m at 100 kHz, from which the linear dynamic range of the sensor is 108.2 dB.