Optical isolators,the photonic analogs of electronic diodes,are essential for ensuring the unidirectional flow of light in optical systems,thereby mitigating the destabilizing effects of back reflections.Thin-film lit...Optical isolators,the photonic analogs of electronic diodes,are essential for ensuring the unidirectional flow of light in optical systems,thereby mitigating the destabilizing effects of back reflections.Thin-film lithium niobate(TFLN),hailed as“the silicon of photonics,”has emerged as a pivotal material in the realm of chip-scale nonlinear optics,propelling the demand for compact optical isolators.We report a breakthrough in the development of a fully passive,integrated optical isolator on the TFLN platform,leveraging the Kerr effect to achieve an impressive 10.3 dB of isolation with a minimal insertion loss of 1.87 dB.Further theoretical simulations have demonstrated that our design,when applied to a microring resonator with a Q factor of 5×10^(6),can achieve 20 dB of isolation with an input power of merely 8 mW.This advancement underscores the immense potential of lithium niobate-based Kerr-effect isolators in propelling the integration and application of high-performance on-chip lasers,heralding a new era in integrated photonics.展开更多
We investigate the dependence of the switching process on the perpendicular magnetic anisotropy （PMA） constant in perpendicular spin transfer torque magnetic tunnel junctions （P-MTJs） using micromagnetic simulatio...We investigate the dependence of the switching process on the perpendicular magnetic anisotropy （PMA） constant in perpendicular spin transfer torque magnetic tunnel junctions （P-MTJs） using micromagnetic simulations. It is found that the final stable states of the magnetization distribution of the free layer after switching can be divided into three different states based on different PMA constants： vortex, uniform, and steady. Different magnetic states can be attributed to a trade-off among demagnetization, exchange, and PMA energies. The generation of the vortex state is also related to the non-uniform stray field from the polarizer, and the final stable magnetization is sensitive to the PMA constant. The vortex and uniform states have different switching processes, and the switching time of the vortex state is longer than that of the uniform state due to hindrance by the vortex.展开更多
In recent years,integrated optical processing units(IOPUs)have demonstrated advantages in energy efficiency and computational speed for neural network inference applications.However,limited by optical integration tech...In recent years,integrated optical processing units(IOPUs)have demonstrated advantages in energy efficiency and computational speed for neural network inference applications.However,limited by optical integration technology,the practicality and versatility of IOPU face serious challenges.In this work,a scalable parallel photonic processing unit(SPPU)for various neural network accelerations based on high-speed phase modulation is proposed and implemented on a silicon-on-insulator platform,which supports parallel processing and can switch between multiple computational paradigms simply and without latency to infer different neural network structures,enabling to maximize the utility of on-chip components.The SPPU adopts a scalable and process-friendly architecture design,with a preeminent photonic-core energy efficiency of 0.83 TOPS/W,two to ten times higher than existing integrated solutions.In the proof-of-concept experiment,a convolutional neural network(CNN),a residual CNN,and a recurrent neural network(RNN)are all implemented on our photonic processor to handle multiple tasks of handwritten digit classification,signal modulation format recognition,and review emotion recognition.The SPPU achieves multi-task parallel processing capability,serving as a promising and attractive research route to maximize the utility of on-chip components under the constraints of integrated technology,which helps to make IOPU more practical and universal.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2022YFF0712800 and 2019YFA0308700)。
文摘Optical isolators,the photonic analogs of electronic diodes,are essential for ensuring the unidirectional flow of light in optical systems,thereby mitigating the destabilizing effects of back reflections.Thin-film lithium niobate(TFLN),hailed as“the silicon of photonics,”has emerged as a pivotal material in the realm of chip-scale nonlinear optics,propelling the demand for compact optical isolators.We report a breakthrough in the development of a fully passive,integrated optical isolator on the TFLN platform,leveraging the Kerr effect to achieve an impressive 10.3 dB of isolation with a minimal insertion loss of 1.87 dB.Further theoretical simulations have demonstrated that our design,when applied to a microring resonator with a Q factor of 5×10^(6),can achieve 20 dB of isolation with an input power of merely 8 mW.This advancement underscores the immense potential of lithium niobate-based Kerr-effect isolators in propelling the integration and application of high-performance on-chip lasers,heralding a new era in integrated photonics.
基金Project supported by the National Natural Science Foundation of China(Grant No.61332003)the Natural Science Foundation of Hunan Province,China(Grant No.2015JJ3024)
文摘We investigate the dependence of the switching process on the perpendicular magnetic anisotropy （PMA） constant in perpendicular spin transfer torque magnetic tunnel junctions （P-MTJs） using micromagnetic simulations. It is found that the final stable states of the magnetization distribution of the free layer after switching can be divided into three different states based on different PMA constants： vortex, uniform, and steady. Different magnetic states can be attributed to a trade-off among demagnetization, exchange, and PMA energies. The generation of the vortex state is also related to the non-uniform stray field from the polarizer, and the final stable magnetization is sensitive to the PMA constant. The vortex and uniform states have different switching processes, and the switching time of the vortex state is longer than that of the uniform state due to hindrance by the vortex.
基金National Natural Science Foundation of China(11902358,62302504)。
文摘In recent years,integrated optical processing units(IOPUs)have demonstrated advantages in energy efficiency and computational speed for neural network inference applications.However,limited by optical integration technology,the practicality and versatility of IOPU face serious challenges.In this work,a scalable parallel photonic processing unit(SPPU)for various neural network accelerations based on high-speed phase modulation is proposed and implemented on a silicon-on-insulator platform,which supports parallel processing and can switch between multiple computational paradigms simply and without latency to infer different neural network structures,enabling to maximize the utility of on-chip components.The SPPU adopts a scalable and process-friendly architecture design,with a preeminent photonic-core energy efficiency of 0.83 TOPS/W,two to ten times higher than existing integrated solutions.In the proof-of-concept experiment,a convolutional neural network(CNN),a residual CNN,and a recurrent neural network(RNN)are all implemented on our photonic processor to handle multiple tasks of handwritten digit classification,signal modulation format recognition,and review emotion recognition.The SPPU achieves multi-task parallel processing capability,serving as a promising and attractive research route to maximize the utility of on-chip components under the constraints of integrated technology,which helps to make IOPU more practical and universal.
