We report a vertically coupled germanium (Ge) waveguide detector integrated on silicon-on-insulator waveguides and an optimized device structure through the analysis of the optical field distribution and absorption efficiency of the device. The photodetector we designed is manufactured by IMEC, and the tests show that the device has good performance. This study theoretically and experimentally explains the structure of Ge PIN and the effect of the photodetector (PD) waveguide parameters on the performance of the device. Simulation and optimization of waveguide detectors with different structures are carried out. The device’s structure, quantum efficiency, spectral response, response current, changes with incident light strength, and dark current of PIN-type Ge waveguide detector are calculated. The test results show that approximately 90% of the light is absorbed by a Ge waveguide with 20 μm Ge length and 500 nm Ge thickness. The quantum efficiency of the PD can reach 90.63%. Under the reverse bias of 1 V, 2 V and 3 V, the detector’s average responsiveness in C-band reached 1.02 A/W, 1.09 A/W and 1.16 A/W and the response time is 200 ns. The dark current is only 3.7 nA at the reverse bias voltage of −1 V. The proposed silicon-based Ge PIN PD is beneficial to the integration of the detector array for photonic integrated arrayed waveguide grating (AWG)-based fiber Bragg grating (FBG) interrogators.

When a dynamic balancing measuring system is equipped with velocity sensor as its vibration pick-up, the output signal of the sensor is proportional to the third power of rotating speed of the balancing operation. Generally a third order low-pass filter circuit is often used to eliminate the influence of rotating speed and suppress the high frequency interference as well. However, the frequency response of third order low-pass filter circuit can’t compensate completely for the response characteristic of the vibration system of balancing machine, which then causes measuring error. So, as a general purpose hard bearing dynamic balancing machine being suitable for a wide speed range, frequency compensation must be conducted. The approach of frequency compensation is classified into two broad types: hardware and software compensation. This paper conducts further research on these two methods to improve the accuracy of the measuring system and proves the accuracy and effectiveness of the two methods by signal simulation and field experiments.

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Aiming at extracting sinusoidal signals from strong background noise and disturbance under the constraint of limited cycles of samples, the spectral feature of the picked unbalance vibration signal of a hard bearing balancing machine was analyzed and an analogue filter was designed to eliminate the main disturbance components in the frequency domain, and a signal extension method based on the AR model was introduced and investigated. Simulation and field experiments demonstrated the feasibility of the presented extension method and an improvement in accuracy was achieved by extension of the AR model.