Multi-functional optical fiber sensor system based on a dense wavelength division multiplexer

We propose a novel and efficient multi-functional optical fiber sensor system based on a dense wavelength division multiplexer(DWDM).This system consists of an optical fiber temperature sensor, an optical fiber strain sensor, and a 48-channel DWDM.This system can monitor temperature and strain changes at the same time.The ranges of these two sensors are from-20℃ to 100℃ and from-1000 με to 2000 με, respectively.The sensitivities of the temperature sensor and strain sensor are 0.03572 nm/℃ and 0.03808 nm/N, respectively.With the aid of a broadband source and spectrometer,different kinds and ranges of parameters in the environment can be monitored by using suitable sensors.

Low-power electro-optic phase modulator based on multilayer graphene/silicon nitride waveguide

Electro-optic modulator is a key component for on-chip optical signal processing.An electro-optic phase modulator based on multilayer graphene embedded in silicon nitride waveguide is demonstrated to fulfill low-power operation.Finite element method is adopted to investigate the interaction enhancement between the graphene flake and the optical mode.The impact of multilayer graphene on the performance of phase modulator is studied comprehensively.Simulation results show that the modulation efficiency improves with the increment of graphene layer number,as well as the modulation length.The 3-dB bandwidth of around 48 GHz is independent of graphene layer number and length.Compared to modulator with two-or four-layer graphene,the six-layer graphene/silicon nitride waveguide modulator can realizeπphase shift at a low-power consumption of 14 fJ/bit when the modulation length is 240μm.

Flexible Strain Sensor Based on 3D Electrospun Carbonized Sponge

Flexible strain sensor has attracted much attention because of its potential application in human motion detection.In this work,the prepared strain sensor was obtained by encapsulating electrospun carbonized sponge(CS)with room temperature vulcanized silicone rubber(RTVS).In this paper,the formation mechanism of conductive sponge was studied.Based on the combination of carbonized sponge and RTVS,the strain sensing mechanism and piezoresistive properties are discussed.After research and testing,the CS/RTVS flexible strain sensor has excellent fast response speed and stability,and the maximum strain coefficient of the sensor is 136.27.In this study,the self-developed CS/RTVS sensor was used to monitor the movements of the wrist joint,arm elbow joint and fingers in real time.Research experiments show that CS/RTVS flexible strain sensor has good application prospects in the field of human motion monitoring.

10-GHz broadband optical frequency comb generation at 1550/1310 nm

The generation of high-repetition rate(frep≥10 GHz)ultra-broadband optical frequency combs(OFCs)at 1550 nm and 1310 nm is investigated by seeding two types of highly nonlinear fibers(HNLFs)with 10 GHz picosecond pulses at the pump wavelength of 1550 nm.When pumped near the zero dispersion wavelength(ZDW)in the normal dispersion region of a HNLF,10 GHz flat-topped OFC with 43 nm bandwidth within 5 dB power variation is generated by self-phase modulation(SPM)-based OFC spectral broadening at 26.5 dBm pump power,and 291 fs pulse trains with 10 GHz repetition rate are obtained at 18 dBm pump power without complicated pulse shaping methods.Furthermore,when pumped in the abnormal dispersion region of a HNLF,OFCs with dispersive waves around 1310 nm are studied using a common HNLF and fluorotellurite fibers,which maintain the good coherence of the pump light at 1550 nm.At the same time,sufficient tunability of the generated dispersive waves is achieved when tuning the pump power or ZDW.

Impact of demand growth on the capacity of long-duration energy storage under deep decarbonization

The weather-dependent uncertainty of wind and solar power generation presents a challenge to the balancing of power generation and demand in highly renewable electricity systems.Battery energy storage can provide flexibility to firm up the variability of renewables and to respond to the increased load demand under decarbonization scenarios.This paper explores how the battery energy storage capacity requirement for compressed-air energy storage(CAES)will grow as the load demand increases.Here we used an idealized lowest-cost optimization model to study the response of highly renewable electricity systems to the increasing load demand of California under deep decarbonization.Results show that providing bulk CAES to the zero-emission power system offers substantial benefits,but it cannot fully compensate for the 100%variability of highly renewable power systems.The capacity requirement of CAES increases by≤33.3%with a 1.5 times increase in the load demand and by≤50%with a two-times increase in the load demand.In this analysis,a zero-emission electricity system operating at current costs becomes more cost-effective when there is firm power generation.The least competitive nuclear option plays this role and reduces system costs by 16.4%,curtails the annual main node by 36.8%,and decreases the CAES capacity requirements by≤80.7%in the case of a double-load demand.While CAES has potential in addressing renewable variability,its widespread deployment is constrained by geographical,societal,and economic factors.Therefore,if California is aiming for an energy system that is reliant on wind and solar power,then an additional dispatchable power source other than CAES or similar load flexibility is necessary.To fully harness the benefits of bulk CAES,the development and implementation of cost-effective approaches are crucial in significantly reducing system costs.

Mode-insensitive and mode-selective optical switch based on asymmetric Y-junctions and MMI couplers

Driven by the large volume demands of data in transmission systems,the number of spatial modes supported by mode-division multiplexing(MDM)systems is being increased to take full advantage of the parallelism of the signals in different spatial modes.As a key element for photonic integrated circuits,the multimode waveguide optical switch(MWOS)is playing an important role for data exchange and signal switching.However,the function of the traditional MWOS is simple,which could only implement the mode-insensitive or mode-selective switching function;it is also difficult to scale to accommodate more spatial modes because of the limitation of the device structure.Therefore,it is still challenging to realize a multifunctional and scalable MWOS that could support multiple modes with low power consumption and high flexibility.Here,we propose and experimentally demonstrate a multifunctional MWOS based on asymmetric Y-junctions and multimode interference(MMI)couplers fabricated on a polymer waveguide platform.Both mode-insensitive and mode-selective switching functions can be achieved via selectively heating different electrode heaters.The fabricated device with the total length of∼0.8 cmshows an insertion loss of less than 12.1 dB,and an extinction ratio of larger than 8.4 dB with a power consumption of∼32 mW for both mode-insensitive and mode-selective switching functions,at 1550 nm wavelength.The proposed MWOS can also be scaled to accommodate more spatial modes flexibly and easily,which can serve as an important building block for MDM systems.

新型冠状病毒肺炎疫情对放射科住院医师规范化培训的影响及思考

我国放射科住院医师规范化培训发展迅速,在新型冠状病毒肺炎疫情防控期间,大量教学内容转化为线上教育,面临线上教学条件和资源不足,在线课程互动不足等挑战,为此,我们需要加强线上课程资源建设,增加线上课程的互动交流,优化医学影像学人才的培养体系。

Cross-cascaded AWG-based wavelength selective switching integrated module using polymer optical waveguide circuits

100-GHz cross-cascaded arrayed waveguide gratings （AWGs）-based wavelength selective optical switching optical cross-connects （OXCs） modules with Mach-Zehnder interferometer （MZI） thermo-optic （TO） variable optical attenuator （VOA） arrays and optical true- time-delay （TTD） line arrays is successfully designed and fabricated using polymer photonic lightwave circuit. Highly fluorinated photopolymer and grafting modified organic-inorganic hybrid material were synthesized as the waveguide core and cladding, respectively. The one-chip transmission loss is -6 dB and the crosstalk is less than -30 dB for the transverse-magnetic （TM） mode. The actual maximum modulation depths of different thermo-optic switches are similar, -15.5 dB with 1.9 V bias. The maximum power consumption of a single switch is less than 10 mW. The delay time basic increments are measured from 140 to 20 ps. Proposed novel module is flexible and scalable for the dense wavelength division multiplexing network.

Simultaneous Accelerator Parallelization and Point-to-Point Interconnect Insertion for Bus-Based Embedded SoCs

As performance requirements for bus-based embedded System-on-Chips(So Cs) increase, more and more on-chip application-specific hardware accelerators(e.g., filters, FFTs, JPEG encoders, GSMs, and AES encoders) are being integrated into their designs. These accelerators require system-level tradeoffs among performance, area, and scalability. Accelerator parallelization and Point-to-Point(P2P) interconnect insertion are two effective system-level adjustments. The former helps to boost the computing performance at the cost of area,while the latter provides higher bandwidth at the cost of routability. What’s more, they interact with each other. This paper proposes a design flow to optimize accelerator parallelization and P2 P interconnect insertion simultaneously.To explore the huge optimization space, we develop an effective algorithm, whose goal is to reduce total So C latency under the constraints of So C area and total P2 P wire length. Experimental results show that the performance difference between our proposed algorithm and the optimal results is only 2.33% on average, while the running time of the algorithm is less than 17 s.