Design And Phase Optimization Of 4x4cascade MZI Photonic Circuit

Over the years,the development of deep neural networks has also been very rapid.It has made great progress in the artificial intelligence community and has received many attentions.Researchers designed different structures based on deep neural networks and applied them to many fields such as medicine,business,manufacturing,and life,which effectively avoided tedious human work and increased accuracy.Although neural networks have brought convenience to society,with the exponential accumulation of data problems and the limitations of Moore's Law,neural networks based on electronic chips will gradually reach their computational bottleneck.Since the integrated photonic circuit was proposed,the development prospects of the photonic circuit have been widely concerned.The integrated photonic chip is favored by researchers due to its unique advantages.Due to the physical characteristics of light,the photonic chip can complete the specified tasks with ultra-high speed,high bandwidth and low power consumption when working,which undoubtedly provides the hardware foundation for the deep neural network which values power consumption and processing speed.Photonic neural networks based on photonic chips have also emerged.Based on the development status mentioned above,the research contents of this paper are as follows:(1)The singular value decomposition(SVD)method proposed in most studies is not used to design photonic circuits in this paper.Instead,we use multiple phasecontrollable 2×2 optical devices Mach-Zehnder interferometer(MZI)as the basic unit.Through the multi-stage cascade method,a triangular array structure is used to design a cascaded photonic circuit that can clone a 4×4 complex-valued weight matrix W.And we can change the complex-valued matrix represented by the optical path by changing the phases in the cascaded photonic circuit.In addition,the mathematical matrix expression form of the designed 4×4 cascaded photonic circuit is calculated through the matrix expression form of Mach-Zehnder interferometer in this paper;(2)Proposing a phase-determination system based on the foundation of nonlinear least squares algorithm.The system determines the optimal phases in each MZI of the designed 4×4 cascaded photonic circuit when cloning the complex-valued weight matrix W.At the same time,the robustness of the phase determination system is tested through experiments.(3)Using the 4×4 cascade photonic circuit to clone the 4×4 complex-valued weight matrix W.The phase-determination system is utilized to initialize and optimize the phase parameters in the 4×4 cascade photonic circuit to obtain the results of the phase groups.Comparing the differences between the phase of the result and the standard through the comparison of the data.The pros and cons of the cloning effect can be intuitively evaluated.Research shows that the designed 4×4 cascaded photonic circuit without SVD can realize the cloning of the 4×4 complex-valued weight matrix W to a certain extent.