A modulator is an essential building block in the integrated photonics,connecting the electrical with optical signals.The microring modulator gains much attention because of the small footprint,low drive voltage and h...A modulator is an essential building block in the integrated photonics,connecting the electrical with optical signals.The microring modulator gains much attention because of the small footprint,low drive voltage and high extinction ratio.An ultra-low V_(pp)and high-modulation-depth indium phosphide-based racetrack microring modulator is demonstrated in this paper.The proposed device mainly comprises one racetrack microring,incorporating a semiconductor amplifier,and coupling with a bus waveguide through a multimode interference coupler.Traveling wave electrodes are employed to supply bidirectional bias ports,terminating with a 50-Ω impedance.The on/off extinction ratio of the microring reaches 43.3 dB due to the delicately tuning of the gain.An 11 mV V_(pp),a maximum 42.5 dB modulation depth and a 6.6 GHz bandwidth are realized,respectively.This proposed microring modulator could enrich the functionalities and designability of the fundamental integrated devices.展开更多
We propose a novel high-performance digital optical sensor based on the Mach-Zehnder interferential effect and the dual-microring resonators with the waveguide-coupled feedback. The simulation results show that the se...We propose a novel high-performance digital optical sensor based on the Mach-Zehnder interferential effect and the dual-microring resonators with the waveguide-coupled feedback. The simulation results show that the sensitivity of the sensor can be orders of magnitude higher than that of aconventional sensor, and high quality factor is not critical in it. Moreover, by optimizing the length of the feedback waveguide to be equal to the perimeter of the ring, the measurement range of the proposed sensor is twice as much as that of the conventional sensor in the weak coupling case.展开更多
This paper investigated the design and the characterization of a photonic delay line based on passive cascaded silicon-on-insulator （SOI） microrings. We considered the compromise of group delay, bandwidth and insert...This paper investigated the design and the characterization of a photonic delay line based on passive cascaded silicon-on-insulator （SOI） microrings. We considered the compromise of group delay, bandwidth and insertion loss. A 3-stage double channel side-coupled integrated spaced sequence of resonator （SCISSOR） device was optimized by shifting the resonance of each microring and fabricated with electron beam lithography and dry etching. The group delay was measured to be 17 ps for non-return-to-zero signals at different bit rates and the bandwidth of 78 GHz was achieved. The experiment result agreed well with our simulation.展开更多
To improve the output characteristics of all-fiber Mach-Zehnder interferometer(MZI)-interleaver,a dual microring-assisted MZI interleaver is designed.According to its structure,the output expression of the device is d...To improve the output characteristics of all-fiber Mach-Zehnder interferometer(MZI)-interleaver,a dual microring-assisted MZI interleaver is designed.According to its structure,the output expression of the device is derived from the signal flow diagram.After simulation analysis,the optimal structural parameters during the transmission process are obtained.In addition,the coupling coefficient and transmission loss of the coupler are analyzed.The results show that the improved interleaver output line wave is closer to the square wave,and its 25 dB cutoff band bandwidth and 0.5 dB passband bandwidth are significantly improved,with the values of 41.2 GHz and 18.9 GHz,respectively.The device has a certain resistantability to deviation,and the transmission loss has less influence on the extinction characteristics of the filter.展开更多
We designed a reconfigurable dual-interferometer coupled silicon nitride microring resonator.By tuning the integrated heater on interferometer's arms,the"critical coupling"bandwidth of resonant mode is c...We designed a reconfigurable dual-interferometer coupled silicon nitride microring resonator.By tuning the integrated heater on interferometer's arms,the"critical coupling"bandwidth of resonant mode is continuously adjustable whose quality factor varies from 7.9×10^(4) to 1.9×10^(5) with the extinction ratio keeping higher than 25 dB.Also a variety of coupling spanning from"under-coupling"to"over-coupling"were achieved,showing the ability to tune the quality factor from 6.0×10^(3) to 2.3×10^(5).Our design can provide an adjustable filtering method on silicon nitride photonic chip and contribute to optimize the nonlinear process for quantum photonics and all-optical signal processing.展开更多
A high-performance microring resonator in a silicon-on-insulator rib waveguide is realized by using the electron beam lithography followed by inductively coupled plasma etching. The design and the experimental realiza...A high-performance microring resonator in a silicon-on-insulator rib waveguide is realized by using the electron beam lithography followed by inductively coupled plasma etching. The design and the experimental realization of this device are presented in detail. In addition to improving relevant processes to minimize propagation loss, the coupling efficiency between the ring and the bus is carefully chosen to approach a critical coupling for high performance operating. We have measured a quality factor of 21,200 and an extinction ratio of 12.SdB at a resonant wavelength of 1549.32nm. Meanwhile, a low propagation loss of 0.89dB/mm in a curved waveguide with a bending radius of 40μm is demonstrated as well.展开更多
On the silicon-on-insulator platform, an ultra compact temperature-insensitive modulator based on a cascaded microring assistant Mach-Zehnder interferometer is proposed and demonstrated with numerical simulation. Acco...On the silicon-on-insulator platform, an ultra compact temperature-insensitive modulator based on a cascaded microring assistant Mach-Zehnder interferometer is proposed and demonstrated with numerical simulation. According to the calculated results, the tolerated variation of ambient temperature can be as high as 134 ℃ while the footprint of such a silicon modulator is only 340 μm2.展开更多
We propose a novel resonator containing an elliptical microring based on a silicon-on-insulator platform. Simu- lations using the three-dimensional finite-difference time-domain method show that the novel elliptical m...We propose a novel resonator containing an elliptical microring based on a silicon-on-insulator platform. Simu- lations using the three-dimensional finite-difference time-domain method show that the novel elliptical microring can efficiently enhance the mode coupling between straight bus waveguides and resonator waveguides or between adjacent resonators while preserving relatively high intrinsic quality factors with large free spectral range. The proposed resonator would be an alternative choice for future high-density integrated photonic circuits.展开更多
High-dimensional entanglement provides valuable resources for quantum technologies,including quantum communication,quantum optical coherence tomography,and quantum computing.Obtaining a high brightness and dimensional...High-dimensional entanglement provides valuable resources for quantum technologies,including quantum communication,quantum optical coherence tomography,and quantum computing.Obtaining a high brightness and dimensional entanglement source has significant value.Here we utilize a tunable asymmetric Mach–Zehnder interferometer coupled silicon microring resonator with 100 GHz free spectral range to achieve this goal.With the strategy of the tunable coupler,the dynamical and extensive tuning range of quality factors of the microring can be obtained,and then the biphoton pair generation rate can be optimized.By selecting and characterizing 28 pairs from a more than 30-pair modes biphoton frequency comb,we obtain a Schmidt number of at least 23.4 and on-chip pair generation rate of 19.9 MHz/m W;under a low on-chip pump power,which corresponds to 547 dimensions Hilbert space in frequency freedom.These results will prompt the wide applications of quantum frequency comb and boost the further large density and scalable on-chip quantum information processing.展开更多
We experimentally engineer a high-spectral-purity single-photon source using a single-interferometer-coupled silicon microring. By the reconfiguration of the interferometer, different coupling conditions can be obtain...We experimentally engineer a high-spectral-purity single-photon source using a single-interferometer-coupled silicon microring. By the reconfiguration of the interferometer, different coupling conditions can be obtained, corresponding to different quality factors for the pump and signal/idler. The ratio between the quality factor of the pump and signal/idler ranges from 0.29 to 2.57. By constructing the signal–idler joint spectral intensity, we intuitively demonstrate the spectral correlation of the signal and idler. As the ratio between the quality factor of the pump and signal/idler increases, the spectral correlation of the signal and idler decreases, i.e., the spectral purity of the signal/idler photons increases. Furthermore,time-integrated second-order correlation of the signal photons is measured, giving a value up to 94.95 ± 3.46%. Such high-spectral-purity photons will improve the visibility of quantum interference and facilitate the development of on-chip quantum information processing.展开更多
The silicon-based arrayed waveguide grating(AWG)is widely used due to its compact footprint and its compatibility with the mature CMOS process.However,except for AWGs with ridged waveguides of a few micrometers of cro...The silicon-based arrayed waveguide grating(AWG)is widely used due to its compact footprint and its compatibility with the mature CMOS process.However,except for AWGs with ridged waveguides of a few micrometers of cross section,any small process error will cause a large phase deviation in other AWGs,resulting in an increasing cross talk.In this paper,an ultralow cross talk AWG via a tunable microring resonator(MRR)filter is demonstrated on the SOI platform.The measured insertion loss and minimum adjacent cross talk of the designed AWG are approximately 3.2 and-45.1 d B,respectively.Compared with conventional AWG,its cross talk is greatly reduced.展开更多
Silicon nitride(Si3N4)waveguides with high confinement and low loss have been widely used in integrated nonlinear photonics.Indeed,state-of-the-art ultralow-loss Si3N4 waveguides are all fabricated using complex fabri...Silicon nitride(Si3N4)waveguides with high confinement and low loss have been widely used in integrated nonlinear photonics.Indeed,state-of-the-art ultralow-loss Si3N4 waveguides are all fabricated using complex fabrication processes,and all of those reported that high Q microring resonators(MRRs)are fabricated in laboratories.We propose and demonstrate an ultralow-loss Si3N4 racetrack MRR by shaping the mode using a uniform multimode structure to reduce its overlap with the waveguide.The MRR is fabricated by the standard multi project wafer(MPW)foundry process.It consists of two multimode straight waveguides(MSWs)connected by two multimode waveguide bends(MWBs).In particular,the MWBs are based on modified Euler bends,and an MSW directional coupler is used to avoid higher-order mode excitation.In this way,although a multimode waveguide is used in the MRR,only the fundamental mode is excited and transmitted with ultralow loss.Meanwhile,thanks to the 180 deg Euler bend,a compact chip footprint of 2.226 mm perimeter with an effective radius as small as 195μm and a waveguide width of 3μm is achieved.Results show that based on the widely used MPW process,a propagation loss of only 3.3 dB∕m and a mean intrinsic Q of around 10.8 million are achieved for the first time.展开更多
Non-Hermitian systems with their spectral degeneracies known as exceptional points(EPs)have been explored for lasing,controlling light transport,and enhancing a sensor’s response.A ring resonator can be brought to an...Non-Hermitian systems with their spectral degeneracies known as exceptional points(EPs)have been explored for lasing,controlling light transport,and enhancing a sensor’s response.A ring resonator can be brought to an EP by controlling the coupling between its frequency degenerate clockwise and counterclockwise traveling modes.This has been typically achieved by introducing two or more nanotips into the resonator’s mode volume.While this method provides a route to study EP physics,the basic understanding of how the nanotips’shape and size symmetry impact the system’s non-Hermicity is missing,along with additional loss from both in-plane and out-of-plane scattering.The limited resonance stability poses a challenge for leveraging EP effects for switches or modulators,which requires stable cavity resonance and fixed laser-cavity detuning.Here we use lithographically defined asymmetric and symmetric Mie scatterers,which enable subwavelength control of wave transmission and reflections without deflecting to additional radiation channels.We show that those pre-defined Mie scatterers can bring the system to an EP without post tuning,as well as enable chiral light transport within the resonator.Counterintuitively,the Mie scatterer results in enhanced quality factor measured on the transmission port,through coherently suppressing the backscattering from the waveguide surface roughness.The proposed device platform enables pre-defined chiral light propagation and backscattering-free resonances,needed for various applications such as frequency combs,solitons,sensing,and other nonlinear optical processes such as photon blockade,and regenerative oscillators.展开更多
Microring-based optical switches are promising for wavelength-selective switching with the merits of compact size and low power consumption.However,the large insertion loss,the high fabrication,and the temperature sen...Microring-based optical switches are promising for wavelength-selective switching with the merits of compact size and low power consumption.However,the large insertion loss,the high fabrication,and the temperature sensitivity hinder the scalability of silicon microring optical switch fabrics.In this paper,we utilize a three-dimensional(3D)microring-based optical switch element(SE)on a multi-layer Si_(3)N_(4)-on-SOI platform to realize highperformance large-scale optical switch fabrics.The 3D microring-based SE consists of a Si∕Si_(3)N_(4) waveguide overpass crossing in the bottom and the top layers,and Si_(3)N_(4) dual-coupled microring resonators(MRRs)in the middle layer.The switch is calibration-free and has low insertion loss.With the 3D microring-based SEs,we implement an 8×8 crossbar optical switch fabric.As the resonance wavelengths of all SEs are well aligned,only one SE needs to be turned on in each routing path,which greatly reduces the complexity of the switch control.The optical transmission spectra show a box-like shape,with a passband width of~69 GHz and an average on-state loss of~0.37 dB.The chip has a record-low on-chip insertion loss of 0.52-2.66 dB.We also implement a non-duplicate polarization-diversity optical switch by using the bidirectional transmission characteristics of the crossbar architecture,which is highly favorable for practical applications.100 Gb/s dual-polarization quadrature-phase-shift-keying(DP-QPSK)signal is transmitted through the switch without significant degradation.To the best of our knowledge,this is the first time that 3D MRRs have been used to build highly scalable polarization-diversity optical switch fabrics.展开更多
As a resonator-based optical hardware in analog optical computing, a microring synapse can be straightforwardly configured to simulate the connection weights between neurons, but it faces challenges in precision and s...As a resonator-based optical hardware in analog optical computing, a microring synapse can be straightforwardly configured to simulate the connection weights between neurons, but it faces challenges in precision and stability due to cross talk and environmental perturbations. Here, we propose and demonstrate a self-calibration scheme with dual-wavelength synchronization to monitor and calibrate the synaptic weights without interrupting the computation tasks. We design and fabricate an integrated 4 × 4 microring synapse and deploy our self-calibration scheme to validate its effectiveness. The precision and robustness are evaluated in the experiments with favorable performance, achieving 2-bit precision improvement and excellent robustness to environmental temperature fluctuations(the weights can be corrected within 1 s after temperature changes 0.5°C). Moreover, we demonstrate matrix inversion tasks based on Newton iterations beyond 7-bit precision using this microring synapse. Our scheme provides an accurate and real-time weight calibration independently parallel from computations and opens up new perspectives for precision boost solutions to large-scale analog optical computing.展开更多
A compact on-chip reconfigurable multichannel amplitude equalizer based on cascaded elliptical microrings is proposed and demonstrated experimentally.With the optimized structure of the elliptical microring with adiab...A compact on-chip reconfigurable multichannel amplitude equalizer based on cascaded elliptical microrings is proposed and demonstrated experimentally.With the optimized structure of the elliptical microring with adiabatically varied radii/widths,the average excess loss for each channel in the initialized state is measured to be less than 0.5 d B,while the attenuation dynamic range can be over 20 d B.Flexible tunability through the overlapping of the resonance peaks of adjacent wavelength-channels enables even higher attenuation dynamic ranges up to50 d B.Leveraging the thermo-optic effect and fine wavelength-tuning linearity,precise tuning of the resonance peak can be implemented,enabling dynamic power equalization of each wavelength-channel in wavelengthdivision-multiplexing(WDM)systems and optical frequency combs.The proposed architecture exhibits excellent scalability,which can facilitate the development of long-haul optical transport networks and high-capacity neuromorphic computing systems,while improving the overall performance of optical signals in WDM-related systems.展开更多
We propose an integrated W-band transmitter enabled by an integrated dual-mode distributed feedback(DFB)laser and cascaded silicon photonic microring modulators for next-generation wireless communication.10 Gb/s error...We propose an integrated W-band transmitter enabled by an integrated dual-mode distributed feedback(DFB)laser and cascaded silicon photonic microring modulators for next-generation wireless communication.10 Gb/s error-free intensity modulation and direct detection W-band transmission are achieved in experiments by using the dual-mode DFB laser and two free-running lasers.Moreover,we conduct an experiment of dual-carrier modulation based on cascaded microring modulators,achieving 3 dB signal-to-noise ratio improvement and better signaling integrity for wireless communication.The proposed photonic integrated W-band transmitter will be a viable solution for a high-speed and low-power wireless communication system.展开更多
The use of microdng resonators to assist in the evanescent field coupling between dissimilar waveguides is proposed and analyzed. Theoretical analysis based on the coupled mode theory and numerical example show that c...The use of microdng resonators to assist in the evanescent field coupling between dissimilar waveguides is proposed and analyzed. Theoretical analysis based on the coupled mode theory and numerical example show that complete cross power transfers can be obtained near the microring resonances. Applications of the device include power dividers, low-power thermo-optic or electro-optic switches, and modulators.展开更多
We demonstrate a hybrid laser with a low intrinsic linewidth of 34.2 Hz and a high fiber-coupled output power of 11.7 dBm,by coupling a Si_(3)N_(4)-based subwavelength hole defect assisted microring reflector(SHDA-MRR...We demonstrate a hybrid laser with a low intrinsic linewidth of 34.2 Hz and a high fiber-coupled output power of 11.7 dBm,by coupling a Si_(3)N_(4)-based subwavelength hole defect assisted microring reflector(SHDA-MRR)to a commercially available distributed feedback semiconductor laser.The proposed SHDA-MRR structure features an accurately controlled reflection response,with the manipulated modal coupling between two degenerate counterpropagating modes induced by a subwavelength hole defect embedded in the microring waveguide.With further joint optimization of cavity parameters,this Si_(3)N_(4) SHDA-MRR structure is expected to reduce the laser intrinsic linewidth to a sub-hertz level.This work explores a low-cost and robust linewidth reduction scheme for the applications of high-speed coherent optical communications systems and high-resolution optical metrology.展开更多
The dynamic characteristics are investigated for a microring laser with an external radius of 12μm subject to external optical injection.Single-mode operation with a side mode suppression ratio of 33.4 dB is realized...The dynamic characteristics are investigated for a microring laser with an external radius of 12μm subject to external optical injection.Single-mode operation with a side mode suppression ratio of 33.4 dB is realized at a biasing current of 25 mA and a temperature of 290 K,and the corresponding small-signal modulation response is obtained with a resonance peak frequency of 7.5 GHz.Under the optical injection from a tunable laser,the improvements of the small-signal modulation response induced by four-wave mixing are observed for the microring laser,which shows an additional resonance peak around the frequency of the beat frequency between the lasing mode and the injecting light.Furthermore,optical generation of a microwave signal is realized by the light beating between the lasing mode and the injecting light measured by a high-speed photodetector and a spectrum analyzer.展开更多
基金supported by the National Natural Science Foundation of China(61535012,61925505)the National Key R&D Program of China(2018YFB2201900)。
文摘A modulator is an essential building block in the integrated photonics,connecting the electrical with optical signals.The microring modulator gains much attention because of the small footprint,low drive voltage and high extinction ratio.An ultra-low V_(pp)and high-modulation-depth indium phosphide-based racetrack microring modulator is demonstrated in this paper.The proposed device mainly comprises one racetrack microring,incorporating a semiconductor amplifier,and coupling with a bus waveguide through a multimode interference coupler.Traveling wave electrodes are employed to supply bidirectional bias ports,terminating with a 50-Ω impedance.The on/off extinction ratio of the microring reaches 43.3 dB due to the delicately tuning of the gain.An 11 mV V_(pp),a maximum 42.5 dB modulation depth and a 6.6 GHz bandwidth are realized,respectively.This proposed microring modulator could enrich the functionalities and designability of the fundamental integrated devices.
基金Project supported by the National Basic Research Program of China(Grant No.2010CB327601)
文摘We propose a novel high-performance digital optical sensor based on the Mach-Zehnder interferential effect and the dual-microring resonators with the waveguide-coupled feedback. The simulation results show that the sensitivity of the sensor can be orders of magnitude higher than that of aconventional sensor, and high quality factor is not critical in it. Moreover, by optimizing the length of the feedback waveguide to be equal to the perimeter of the ring, the measurement range of the proposed sensor is twice as much as that of the conventional sensor in the weak coupling case.
基金Project supported by the National Basic Research Program of China (Grant Nos.2006CB302803 and 2011CB301701)the National Natural Science Foundation of China (Grant No.60877036)+1 种基金State Key Laboratory of Advanced Optical Communication Systems and Networks of China (Grant No.2008SH02)the Knowledge Innovation Program of Institute of Semiconductors,Chinese Academy of Sciences (Grant No.ISCAS2008T10)
文摘This paper investigated the design and the characterization of a photonic delay line based on passive cascaded silicon-on-insulator （SOI） microrings. We considered the compromise of group delay, bandwidth and insertion loss. A 3-stage double channel side-coupled integrated spaced sequence of resonator （SCISSOR） device was optimized by shifting the resonance of each microring and fabricated with electron beam lithography and dry etching. The group delay was measured to be 17 ps for non-return-to-zero signals at different bit rates and the bandwidth of 78 GHz was achieved. The experiment result agreed well with our simulation.
基金National Natural Science Foundation of China(No.61461024)Foundation of a Hundred Youth Talent Training Program of Lanzhou Jiaotong University(No.1520220232)。
文摘To improve the output characteristics of all-fiber Mach-Zehnder interferometer(MZI)-interleaver,a dual microring-assisted MZI interleaver is designed.According to its structure,the output expression of the device is derived from the signal flow diagram.After simulation analysis,the optimal structural parameters during the transmission process are obtained.In addition,the coupling coefficient and transmission loss of the coupler are analyzed.The results show that the improved interleaver output line wave is closer to the square wave,and its 25 dB cutoff band bandwidth and 0.5 dB passband bandwidth are significantly improved,with the values of 41.2 GHz and 18.9 GHz,respectively.The device has a certain resistantability to deviation,and the transmission loss has less influence on the extinction characteristics of the filter.
基金the National Key Research and Development Program of China(Grant Nos.2019YFA0308700and 2017YFA0303700)the National Natural Science Foundation of China(Grant Nos.11627810 and 11690031)the Open Funds from the State Key Laboratory of High Performance Computing of China(HPCL,National University of Defense Technology).
文摘We designed a reconfigurable dual-interferometer coupled silicon nitride microring resonator.By tuning the integrated heater on interferometer's arms,the"critical coupling"bandwidth of resonant mode is continuously adjustable whose quality factor varies from 7.9×10^(4) to 1.9×10^(5) with the extinction ratio keeping higher than 25 dB.Also a variety of coupling spanning from"under-coupling"to"over-coupling"were achieved,showing the ability to tune the quality factor from 6.0×10^(3) to 2.3×10^(5).Our design can provide an adjustable filtering method on silicon nitride photonic chip and contribute to optimize the nonlinear process for quantum photonics and all-optical signal processing.
基金supported by the State Key Development Program for Basic Research of China (Grant Nos 2006CB302803 and2007CB613405)the National High Technology Research and Development Program of China (Grant No 2006AA03Z424)the National Natural Science Foundation of China (Grant No 60577044)
文摘A high-performance microring resonator in a silicon-on-insulator rib waveguide is realized by using the electron beam lithography followed by inductively coupled plasma etching. The design and the experimental realization of this device are presented in detail. In addition to improving relevant processes to minimize propagation loss, the coupling efficiency between the ring and the bus is carefully chosen to approach a critical coupling for high performance operating. We have measured a quality factor of 21,200 and an extinction ratio of 12.SdB at a resonant wavelength of 1549.32nm. Meanwhile, a low propagation loss of 0.89dB/mm in a curved waveguide with a bending radius of 40μm is demonstrated as well.
基金Project supported by the National Basic Research Program of China(Grant Nos.2011CBA00608,2011CBA00303,2011CB301803, and 2010CB327405)the National Natural Science Foundation of China(Grant Nos.61036011 and 61036010)the Project of Science and Technology from the Communication Information Security Control Laboratory
文摘On the silicon-on-insulator platform, an ultra compact temperature-insensitive modulator based on a cascaded microring assistant Mach-Zehnder interferometer is proposed and demonstrated with numerical simulation. According to the calculated results, the tolerated variation of ambient temperature can be as high as 134 ℃ while the footprint of such a silicon modulator is only 340 μm2.
基金Project supported by the National Basic Research Program of China (Grant Nos. 2011CB301701, 2012CB933502, and2012CB933504)the National Natural Science Foundation of China (Grant Nos. 60877036 and 61107048)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KGCX2-EW-102)
文摘We propose a novel resonator containing an elliptical microring based on a silicon-on-insulator platform. Simu- lations using the three-dimensional finite-difference time-domain method show that the novel elliptical microring can efficiently enhance the mode coupling between straight bus waveguides and resonator waveguides or between adjacent resonators while preserving relatively high intrinsic quality factors with large free spectral range. The proposed resonator would be an alternative choice for future high-density integrated photonic circuits.
基金supported by the National Basic Research Program of China(Grant Nos.2019YFA0308700 and 2017YFA0303700)the National Natural Science Foundation of China(Grant Nos.61632021 and 11690031)the Open Funds from the State Key Laboratory of High Performance Computing of China(HPCL,National University of Defense Technology)。
文摘High-dimensional entanglement provides valuable resources for quantum technologies,including quantum communication,quantum optical coherence tomography,and quantum computing.Obtaining a high brightness and dimensional entanglement source has significant value.Here we utilize a tunable asymmetric Mach–Zehnder interferometer coupled silicon microring resonator with 100 GHz free spectral range to achieve this goal.With the strategy of the tunable coupler,the dynamical and extensive tuning range of quality factors of the microring can be obtained,and then the biphoton pair generation rate can be optimized.By selecting and characterizing 28 pairs from a more than 30-pair modes biphoton frequency comb,we obtain a Schmidt number of at least 23.4 and on-chip pair generation rate of 19.9 MHz/m W;under a low on-chip pump power,which corresponds to 547 dimensions Hilbert space in frequency freedom.These results will prompt the wide applications of quantum frequency comb and boost the further large density and scalable on-chip quantum information processing.
基金Project supported by the National Basic Research Program of China (Grant Nos. 2019YFA0308700 and 2017YFA0303700)the Open Funds from the State Key Laboratory of High Performance Computing of China (HPCL, National University of Defense Technology)。
文摘We experimentally engineer a high-spectral-purity single-photon source using a single-interferometer-coupled silicon microring. By the reconfiguration of the interferometer, different coupling conditions can be obtained, corresponding to different quality factors for the pump and signal/idler. The ratio between the quality factor of the pump and signal/idler ranges from 0.29 to 2.57. By constructing the signal–idler joint spectral intensity, we intuitively demonstrate the spectral correlation of the signal and idler. As the ratio between the quality factor of the pump and signal/idler increases, the spectral correlation of the signal and idler decreases, i.e., the spectral purity of the signal/idler photons increases. Furthermore,time-integrated second-order correlation of the signal photons is measured, giving a value up to 94.95 ± 3.46%. Such high-spectral-purity photons will improve the visibility of quantum interference and facilitate the development of on-chip quantum information processing.
基金supported by the National Key Research and Development Program of China(No.2018YFB2200500)the Yunnan Provincial Foundation Program(No.202201AT070202)the National Natural Science Foundation of China(No.62065010)。
文摘The silicon-based arrayed waveguide grating(AWG)is widely used due to its compact footprint and its compatibility with the mature CMOS process.However,except for AWGs with ridged waveguides of a few micrometers of cross section,any small process error will cause a large phase deviation in other AWGs,resulting in an increasing cross talk.In this paper,an ultralow cross talk AWG via a tunable microring resonator(MRR)filter is demonstrated on the SOI platform.The measured insertion loss and minimum adjacent cross talk of the designed AWG are approximately 3.2 and-45.1 d B,respectively.Compared with conventional AWG,its cross talk is greatly reduced.
基金supported by the National Natural Science Foundation of China(Grant No.61975249)the National Key Research and Development Program of China(Grant No.2018YFA0704403)the Program for HUST Academic Frontier Youth Team(Grant No.2018QYTD08).
文摘Silicon nitride(Si3N4)waveguides with high confinement and low loss have been widely used in integrated nonlinear photonics.Indeed,state-of-the-art ultralow-loss Si3N4 waveguides are all fabricated using complex fabrication processes,and all of those reported that high Q microring resonators(MRRs)are fabricated in laboratories.We propose and demonstrate an ultralow-loss Si3N4 racetrack MRR by shaping the mode using a uniform multimode structure to reduce its overlap with the waveguide.The MRR is fabricated by the standard multi project wafer(MPW)foundry process.It consists of two multimode straight waveguides(MSWs)connected by two multimode waveguide bends(MWBs).In particular,the MWBs are based on modified Euler bends,and an MSW directional coupler is used to avoid higher-order mode excitation.In this way,although a multimode waveguide is used in the MRR,only the fundamental mode is excited and transmitted with ultralow loss.Meanwhile,thanks to the 180 deg Euler bend,a compact chip footprint of 2.226 mm perimeter with an effective radius as small as 195μm and a waveguide width of 3μm is achieved.Results show that based on the widely used MPW process,a propagation loss of only 3.3 dB∕m and a mean intrinsic Q of around 10.8 million are achieved for the first time.
基金supported by Defense Advanced Research Projects Agency(N660012114034)Air Force Office of Scientific Research(AFOSR)Multi-University Research Initiative(FA9550-21-1-0202)+1 种基金AFOSR(FA9550-18-1-0235)partially supported by AFOSR(FA9550-18-1-0300).
文摘Non-Hermitian systems with their spectral degeneracies known as exceptional points(EPs)have been explored for lasing,controlling light transport,and enhancing a sensor’s response.A ring resonator can be brought to an EP by controlling the coupling between its frequency degenerate clockwise and counterclockwise traveling modes.This has been typically achieved by introducing two or more nanotips into the resonator’s mode volume.While this method provides a route to study EP physics,the basic understanding of how the nanotips’shape and size symmetry impact the system’s non-Hermicity is missing,along with additional loss from both in-plane and out-of-plane scattering.The limited resonance stability poses a challenge for leveraging EP effects for switches or modulators,which requires stable cavity resonance and fixed laser-cavity detuning.Here we use lithographically defined asymmetric and symmetric Mie scatterers,which enable subwavelength control of wave transmission and reflections without deflecting to additional radiation channels.We show that those pre-defined Mie scatterers can bring the system to an EP without post tuning,as well as enable chiral light transport within the resonator.Counterintuitively,the Mie scatterer results in enhanced quality factor measured on the transmission port,through coherently suppressing the backscattering from the waveguide surface roughness.The proposed device platform enables pre-defined chiral light propagation and backscattering-free resonances,needed for various applications such as frequency combs,solitons,sensing,and other nonlinear optical processes such as photon blockade,and regenerative oscillators.
基金National Key Research and Development Program of China(2019YFB2203200)National Natural Science Foundation of China(62075128,62090052,62135010)Zhejiang Provincial Major Research and Development Program(2021C01199)。
文摘Microring-based optical switches are promising for wavelength-selective switching with the merits of compact size and low power consumption.However,the large insertion loss,the high fabrication,and the temperature sensitivity hinder the scalability of silicon microring optical switch fabrics.In this paper,we utilize a three-dimensional(3D)microring-based optical switch element(SE)on a multi-layer Si_(3)N_(4)-on-SOI platform to realize highperformance large-scale optical switch fabrics.The 3D microring-based SE consists of a Si∕Si_(3)N_(4) waveguide overpass crossing in the bottom and the top layers,and Si_(3)N_(4) dual-coupled microring resonators(MRRs)in the middle layer.The switch is calibration-free and has low insertion loss.With the 3D microring-based SEs,we implement an 8×8 crossbar optical switch fabric.As the resonance wavelengths of all SEs are well aligned,only one SE needs to be turned on in each routing path,which greatly reduces the complexity of the switch control.The optical transmission spectra show a box-like shape,with a passband width of~69 GHz and an average on-state loss of~0.37 dB.The chip has a record-low on-chip insertion loss of 0.52-2.66 dB.We also implement a non-duplicate polarization-diversity optical switch by using the bidirectional transmission characteristics of the crossbar architecture,which is highly favorable for practical applications.100 Gb/s dual-polarization quadrature-phase-shift-keying(DP-QPSK)signal is transmitted through the switch without significant degradation.To the best of our knowledge,this is the first time that 3D MRRs have been used to build highly scalable polarization-diversity optical switch fabrics.
基金National Key Research and Development Program of China(2021YFB2801900,2021YFB2801903)National Natural Science Foundation of China(62075075,62275088,U21A20511)Innovation Project of Optics Valley Laboratory(OVL2021BG001)
文摘As a resonator-based optical hardware in analog optical computing, a microring synapse can be straightforwardly configured to simulate the connection weights between neurons, but it faces challenges in precision and stability due to cross talk and environmental perturbations. Here, we propose and demonstrate a self-calibration scheme with dual-wavelength synchronization to monitor and calibrate the synaptic weights without interrupting the computation tasks. We design and fabricate an integrated 4 × 4 microring synapse and deploy our self-calibration scheme to validate its effectiveness. The precision and robustness are evaluated in the experiments with favorable performance, achieving 2-bit precision improvement and excellent robustness to environmental temperature fluctuations(the weights can be corrected within 1 s after temperature changes 0.5°C). Moreover, we demonstrate matrix inversion tasks based on Newton iterations beyond 7-bit precision using this microring synapse. Our scheme provides an accurate and real-time weight calibration independently parallel from computations and opens up new perspectives for precision boost solutions to large-scale analog optical computing.
基金National Major Research and Development Program(2021YFB2801700,2021YFB2801702)National Science Fund for Distinguished Young Scholars(61725503)+4 种基金National Natural Science Foundation of China(61961146003,62105283,91950205,92150302)Natural Science Foundation of Zhejiang Province(LD19F050001)Zhejiang Provincial Major Research and Development Program(2021C01199)Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2021R01001)Fundamental Research Funds for the Central Universities(2021QNA5002)。
文摘A compact on-chip reconfigurable multichannel amplitude equalizer based on cascaded elliptical microrings is proposed and demonstrated experimentally.With the optimized structure of the elliptical microring with adiabatically varied radii/widths,the average excess loss for each channel in the initialized state is measured to be less than 0.5 d B,while the attenuation dynamic range can be over 20 d B.Flexible tunability through the overlapping of the resonance peaks of adjacent wavelength-channels enables even higher attenuation dynamic ranges up to50 d B.Leveraging the thermo-optic effect and fine wavelength-tuning linearity,precise tuning of the resonance peak can be implemented,enabling dynamic power equalization of each wavelength-channel in wavelengthdivision-multiplexing(WDM)systems and optical frequency combs.The proposed architecture exhibits excellent scalability,which can facilitate the development of long-haul optical transport networks and high-capacity neuromorphic computing systems,while improving the overall performance of optical signals in WDM-related systems.
基金National Key Research and Development Program of China(2019YFB1802903)National Natural Science Foundation of China(62175146,62235011)。
文摘We propose an integrated W-band transmitter enabled by an integrated dual-mode distributed feedback(DFB)laser and cascaded silicon photonic microring modulators for next-generation wireless communication.10 Gb/s error-free intensity modulation and direct detection W-band transmission are achieved in experiments by using the dual-mode DFB laser and two free-running lasers.Moreover,we conduct an experiment of dual-carrier modulation based on cascaded microring modulators,achieving 3 dB signal-to-noise ratio improvement and better signaling integrity for wireless communication.The proposed photonic integrated W-band transmitter will be a viable solution for a high-speed and low-power wireless communication system.
基金funded by the Tsinghua National Laboratory for Information Science and Technology (TNList)
文摘The use of microdng resonators to assist in the evanescent field coupling between dissimilar waveguides is proposed and analyzed. Theoretical analysis based on the coupled mode theory and numerical example show that complete cross power transfers can be obtained near the microring resonances. Applications of the device include power dividers, low-power thermo-optic or electro-optic switches, and modulators.
基金National Key Research and Development Program of China(2018YFB2201802)National Natural Science Foundation of China(61771285).
文摘We demonstrate a hybrid laser with a low intrinsic linewidth of 34.2 Hz and a high fiber-coupled output power of 11.7 dBm,by coupling a Si_(3)N_(4)-based subwavelength hole defect assisted microring reflector(SHDA-MRR)to a commercially available distributed feedback semiconductor laser.The proposed SHDA-MRR structure features an accurately controlled reflection response,with the manipulated modal coupling between two degenerate counterpropagating modes induced by a subwavelength hole defect embedded in the microring waveguide.With further joint optimization of cavity parameters,this Si_(3)N_(4) SHDA-MRR structure is expected to reduce the laser intrinsic linewidth to a sub-hertz level.This work explores a low-cost and robust linewidth reduction scheme for the applications of high-speed coherent optical communications systems and high-resolution optical metrology.
基金the National Natural Science Foundation of China under Grants 61235004,61021003,and 61106048.
文摘The dynamic characteristics are investigated for a microring laser with an external radius of 12μm subject to external optical injection.Single-mode operation with a side mode suppression ratio of 33.4 dB is realized at a biasing current of 25 mA and a temperature of 290 K,and the corresponding small-signal modulation response is obtained with a resonance peak frequency of 7.5 GHz.Under the optical injection from a tunable laser,the improvements of the small-signal modulation response induced by four-wave mixing are observed for the microring laser,which shows an additional resonance peak around the frequency of the beat frequency between the lasing mode and the injecting light.Furthermore,optical generation of a microwave signal is realized by the light beating between the lasing mode and the injecting light measured by a high-speed photodetector and a spectrum analyzer.
