Artificial neural networks have dramatically improved performance for many data processing tasks, including speech and image recognition. Today’s hardware based on von Neumann computering scheme is inefficient at implementing multiply-accumulate operations in neural networks. To tackle this issue, several kinds of electronic architectures have been developed, including GPU, FPGA and ASICs. However, with the gradual end of Moore's law, these architectures still encounter bottlenecks in terms of computation speed and power efficency. Recent years, optical computing technology has attracted much attention for its large bandwith and low latency, and significant effort has been made. Here we propose an integrated photonic chip that is capable of accelerating multiply-accumulate operations. The chip contains a cascaded array of 16 Mach–Zehnder interferometers which can be programmed to perform arbitrary 4×4 matrix. The theory simulation results of the device design are demonstrated.
Grating interferometers are widely used in many miniaturized sensors requiring displacement measurement, such as microphone and accelerometers, because of its small volume and high measurement accuracy. However, the traditional grating can generate a zeroth-order reflected beam, which results in reduced sensor performance, packaging limitations, and laser instability. In this paper, design and manufacture method of a multi-step phase modulation grating is demonstrated. The application of this multi - step grating interferometer is to modulate the intensity of light of level 0 to level ±1 so as to avoid the return to the laser light so as to improve the system stability. On the other hand, due to the increased testing classes of diffraction efficiency, the SNR of the system is improved.
A high dynamic range MOEMS accelerometer based on multi-order diffraction method is presented in this paper. The accelerometer consists of a frequency-stabilized laser source, a diffraction grating, and a mirror attached to a mass block with symmetric cantilever beams, to achieve a few ug resolution. The traditional interferometry only uses the ±1 order diffraction, the accelerometer can obtain high measurement accuracy but the measurement range remains only several mg. This paper introduces a new interferometric method combining ±1 and ±3 order diffraction, and the model of multi-order diffraction measurement is established. The higher order diffraction intensity is proportional to the lower order diffraction intensity, so the higher order diffraction light can be used to improve the dynamic range of the system. And positive and negative order diffraction difference can suppress the common mode noise at the same time. Theoretical analysis and experimental results show that the dynamic range of accelerometer is improved by 9 times under the condition that other conditions remain unchanged.
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