Optical neural networks (ONNs), enabling low latency and high parallel data processing withoutelectromagnetic interference, have become a viable player for fast and energy-efficient processing andcalculation to meet t...Optical neural networks (ONNs), enabling low latency and high parallel data processing withoutelectromagnetic interference, have become a viable player for fast and energy-efficient processing andcalculation to meet the increasing demand for hash rate. Photonic memories employing nonvolatile phase-change materials could achieve zero static power consumption, low thermal cross talk, large-scale, andhigh-energy-efficient photonic neural networks. Nevertheless, the switching speed and dynamic energyconsumption of phase-change material-based photonic memories make them inapplicable for in situ training.Here, by integrating a patch of phase change thin film with a PIN-diode-embedded microring resonator,a bifunctional photonic memory enabling both 5-bit storage and nanoseconds volatile modulation wasdemonstrated. For the first time, a concept is presented for electrically programmable phase-changematerial-driven photonic memory integrated with nanosecond modulation to allow fast in situ training and zerostatic power consumption data processing in ONNs. ONNs with an optical convolution kernel constructedby our photonic memory theoretically achieved an accuracy of predictions higher than 95% when testedby the MNIST handwritten digit database. This provides a feasible solution to constructing large-scalenonvolatile ONNs with high-speed in situ training capability.展开更多
Optical filters are essential parts of advanced optical communication and sensing systems.Among them,the ones with an ultrawide free spectral range(FSR)are especially critical.They are promising to provide access to n...Optical filters are essential parts of advanced optical communication and sensing systems.Among them,the ones with an ultrawide free spectral range(FSR)are especially critical.They are promising to provide access to numerous wavelength channels highly desired for large-capacity optical transmission and multipoint multiparameter sensing.Present schemes for wide-FSR filters either suffer from limited cavity length or poor fabrication tolerance or impose an additional active-tuning control requirement.We theoretically and experimentally demonstrate a filter that features FSR-free operation capability,subnanometer optical bandwidth,and acceptable fabrication tolerance.Only one single deep dip within a record-large waveband(S+C+L band)is observed by appropriately designing a side-coupled Bragg-grating-assisted Fabry–Perot filter,which has been applied as the basic sensing unit for both the refractive index and temperature measurement.Five such basic units are also cascaded in series to demonstrate a multichannel filter.This work provides a new insight to design FSR-free filters and opens up a possibility of flexible large-capacity integration using more wavelength channels,which will greatly advance integrated photonics in optical communication and sensing.展开更多
Free-spectral-range(FSR)-free optical filters have always been a critical challenge for photonic integrated circuits.A high-performance FSR-free filter is highly desired for communication,spectroscopy,and sensing appl...Free-spectral-range(FSR)-free optical filters have always been a critical challenge for photonic integrated circuits.A high-performance FSR-free filter is highly desired for communication,spectroscopy,and sensing applications.Despite significant progress in integrated optical filters,the FSR-free filter with a tunable narrow-band,high out-of-band rejection,and large fabrication tolerance has rarely been demonstrated.In this paper,we propose an exact and robust design method for add-drop filters(ADFs)with an FSR-free operation capability,a sub-nanometer optical bandwidth,and a high out-of-band rejection(OBR)ratio.The achieved filter has a 3-dB bandwidth of<0.5 nm and an OBR ratio of 21.5 dB within a large waveband of 220 nm,which to the best of our knowledge,is the largest-FSR ADF demonstrated on a silicon photonic platform.The filter exhibits large tunability of 12.3 nm with a heating efficiency of 97 pm/mW and maintains the FSR-free feature in the whole tuning process.In addition,we fabri-cated a series of ADFs with different periods,which all showed reliable and excellent performances.展开更多
1.INTRODUCTION The brain−computer interface(BCI)refers to the direct connection created between human or animal brains and external devices to realize the information exchange between the brain and the device,which ha...1.INTRODUCTION The brain−computer interface(BCI)refers to the direct connection created between human or animal brains and external devices to realize the information exchange between the brain and the device,which has developed rapidly in the past few decades in both regulating and recording neural activity.Neuroscientists are utilizing these interfaces to map and analyze the brain’s neural network.1 Since 2005,the emergence of optogenetics technology in neuroscience has made high spatial and cellular resolution stimulation possible,enabling neurons to be turned on and off with unprecedented precision.1 This offers a great opportunity for clinical applications because it provides a way to activate or inactivate specific neurons and directly modulate the neural signal for external activities,bringing hope to patients with neurological disorders such as epilepsy,2 Parkinson’s disease,3 hearing impairment,4 and vision impairment.5 Therefore,it is highly desirable to develop implantable optogenetic devices with the capability of single-cell resolution stimulation and ultrafast neural signal recording that can be positioned at an arbitrary region and depth inside the brain.展开更多
基金supported by the National Key Research and Development Program of China (2019YFB2203002 and 2021YFB2801300)National Natural Science Foundation of China (62105287, 91950204, and 61975179)Zhejiang Provincial Natural Science Foundation (LD22F040002)
文摘Optical neural networks (ONNs), enabling low latency and high parallel data processing withoutelectromagnetic interference, have become a viable player for fast and energy-efficient processing andcalculation to meet the increasing demand for hash rate. Photonic memories employing nonvolatile phase-change materials could achieve zero static power consumption, low thermal cross talk, large-scale, andhigh-energy-efficient photonic neural networks. Nevertheless, the switching speed and dynamic energyconsumption of phase-change material-based photonic memories make them inapplicable for in situ training.Here, by integrating a patch of phase change thin film with a PIN-diode-embedded microring resonator,a bifunctional photonic memory enabling both 5-bit storage and nanoseconds volatile modulation wasdemonstrated. For the first time, a concept is presented for electrically programmable phase-changematerial-driven photonic memory integrated with nanosecond modulation to allow fast in situ training and zerostatic power consumption data processing in ONNs. ONNs with an optical convolution kernel constructedby our photonic memory theoretically achieved an accuracy of predictions higher than 95% when testedby the MNIST handwritten digit database. This provides a feasible solution to constructing large-scalenonvolatile ONNs with high-speed in situ training capability.
基金National Key Research and Development Program of China(2019YFB2203003)National Natural Science Foundation of China(61975179,91950204)Westlake University(the start-up fund of Westlake University).
文摘Optical filters are essential parts of advanced optical communication and sensing systems.Among them,the ones with an ultrawide free spectral range(FSR)are especially critical.They are promising to provide access to numerous wavelength channels highly desired for large-capacity optical transmission and multipoint multiparameter sensing.Present schemes for wide-FSR filters either suffer from limited cavity length or poor fabrication tolerance or impose an additional active-tuning control requirement.We theoretically and experimentally demonstrate a filter that features FSR-free operation capability,subnanometer optical bandwidth,and acceptable fabrication tolerance.Only one single deep dip within a record-large waveband(S+C+L band)is observed by appropriately designing a side-coupled Bragg-grating-assisted Fabry–Perot filter,which has been applied as the basic sensing unit for both the refractive index and temperature measurement.Five such basic units are also cascaded in series to demonstrate a multichannel filter.This work provides a new insight to design FSR-free filters and opens up a possibility of flexible large-capacity integration using more wavelength channels,which will greatly advance integrated photonics in optical communication and sensing.
基金National Key Research and Development Program of China(2019YFB2203003)National Natural Science Foundation of China(62175202 and 91950204)+2 种基金Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2020R01005)the Open Research program of Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang ProvinceWestlake University(the start-up fund of Westlake University).
文摘Free-spectral-range(FSR)-free optical filters have always been a critical challenge for photonic integrated circuits.A high-performance FSR-free filter is highly desired for communication,spectroscopy,and sensing applications.Despite significant progress in integrated optical filters,the FSR-free filter with a tunable narrow-band,high out-of-band rejection,and large fabrication tolerance has rarely been demonstrated.In this paper,we propose an exact and robust design method for add-drop filters(ADFs)with an FSR-free operation capability,a sub-nanometer optical bandwidth,and a high out-of-band rejection(OBR)ratio.The achieved filter has a 3-dB bandwidth of<0.5 nm and an OBR ratio of 21.5 dB within a large waveband of 220 nm,which to the best of our knowledge,is the largest-FSR ADF demonstrated on a silicon photonic platform.The filter exhibits large tunability of 12.3 nm with a heating efficiency of 97 pm/mW and maintains the FSR-free feature in the whole tuning process.In addition,we fabri-cated a series of ADFs with different periods,which all showed reliable and excellent performances.
基金The authors would like to acknowledge the start-up fund of Westlake Universitythe funding support from the Westlake Multidisciplinary Research Initiative Center(MRIC)(Grant No.MRIC20200104).
文摘1.INTRODUCTION The brain−computer interface(BCI)refers to the direct connection created between human or animal brains and external devices to realize the information exchange between the brain and the device,which has developed rapidly in the past few decades in both regulating and recording neural activity.Neuroscientists are utilizing these interfaces to map and analyze the brain’s neural network.1 Since 2005,the emergence of optogenetics technology in neuroscience has made high spatial and cellular resolution stimulation possible,enabling neurons to be turned on and off with unprecedented precision.1 This offers a great opportunity for clinical applications because it provides a way to activate or inactivate specific neurons and directly modulate the neural signal for external activities,bringing hope to patients with neurological disorders such as epilepsy,2 Parkinson’s disease,3 hearing impairment,4 and vision impairment.5 Therefore,it is highly desirable to develop implantable optogenetic devices with the capability of single-cell resolution stimulation and ultrafast neural signal recording that can be positioned at an arbitrary region and depth inside the brain.
