A periodic pipe system composed of steel pipes and rubber hoses with the same inner radius is designed based on the theory of phononic crystals. Using the transfer matrix method, the band structure of the periodic pip...A periodic pipe system composed of steel pipes and rubber hoses with the same inner radius is designed based on the theory of phononic crystals. Using the transfer matrix method, the band structure of the periodic pipe is calculated considering the structural-acoustic coupling. The results show that longitudinal vibration band gaps and acoustic band gaps can coexist in the fluid-filled periodic pipe. The formation of the band gap mechanism is further analyzed. The band gaps are validated by the sound transmission loss and vibration-frequency response functions calculated using the finite element method. The effect of the damp on the band gap is analyzed by calculating the complex band structure. The periodic pipe system can be used not only in the field of vibration reduction but also for noise elimination.展开更多
Passive intermodulation(PIM)in communication systems is an unwanted interference caused by weak nonlinear currentvoltage characteristics of radio frequency(RF)passive components.Characterization of PIM is important fo...Passive intermodulation(PIM)in communication systems is an unwanted interference caused by weak nonlinear currentvoltage characteristics of radio frequency(RF)passive components.Characterization of PIM is important for both the study of PIM mechanisms and the location/suppression of PIM sources.PIM probes,made of open-ended coaxial transmission lines,have almost the same coupling strength to carriers and PIM products,and are usually used for near-field PIM characterization.Namely,it doesn’t have any filtering capability.Therefore,it cannot stop the carrier power from entering into PIM tester’s receiver,which may trigger active intermodulation of the receiver and degrade the PIM tester’s performance.To overcome this drawback,a passive filtering coaxial probe is proposed here.Compared with existing passive coaxial PIM probes,it has stronger coupling strength for PIM products than for carriers.Thus,the probe itself can block part of the carrier power entering into the PIM tester’s receiver.This advantage helps improve PIM tester’s overall performance.Both theoretical analysis and experiments are conducted for demonstration.The proposed probe brings more possibility to PIM characterization.展开更多
Optical micro-resonators have broad applications.They are used,for example,to enhance light–matter interactions in optical sensors or as model systems for investigating fundamental physical mechanisms in cavity quant...Optical micro-resonators have broad applications.They are used,for example,to enhance light–matter interactions in optical sensors or as model systems for investigating fundamental physical mechanisms in cavity quantum electrodynamics.Coupling two or more micro-cavities is particularly interesting as it enlarges the design freedom and the field of application.In this context,achieving tunability of the coupling strength and hence the inter-cavity gap is of utmost importance for adjusting the properties of the coupled micro-resonator system.In this paper,we report on a novel coupling approach that allows highly precise tuning of the coupling gap of polymeric micro-resonators that are fabricated side by side on a common substrate.We structure goblet-shaped whispering-gallery-mode resonators on an elastic silicone-based polymer substrate by direct laser writing.The silicone substrate is mechanically stretched in order to exploit the lateral shrinkage to reduce the coupling gap.Incorporating a laser dye into the micro-resonators transforms the cavities into micro-lasers that can be pumped optically.We have investigated the lasing emission by micro-photoluminescence spectroscopy,focusing on the spatial localization of the modes.Our results demonstrate the formation of photonic molecules consisting of two or even three resonators,for which the coupling strengths and hence the lasing performance can be precisely tuned.Flexibility and tunability are key elements in future photonics,making our approach interesting for various photonic applications.For instance,as our coupling approach can also be extended to larger cavity arrays,it might serve as a platform for tunable coupled-resonator optical waveguide devices.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11372346
文摘A periodic pipe system composed of steel pipes and rubber hoses with the same inner radius is designed based on the theory of phononic crystals. Using the transfer matrix method, the band structure of the periodic pipe is calculated considering the structural-acoustic coupling. The results show that longitudinal vibration band gaps and acoustic band gaps can coexist in the fluid-filled periodic pipe. The formation of the band gap mechanism is further analyzed. The band gaps are validated by the sound transmission loss and vibration-frequency response functions calculated using the finite element method. The effect of the damp on the band gap is analyzed by calculating the complex band structure. The periodic pipe system can be used not only in the field of vibration reduction but also for noise elimination.
文摘Passive intermodulation(PIM)in communication systems is an unwanted interference caused by weak nonlinear currentvoltage characteristics of radio frequency(RF)passive components.Characterization of PIM is important for both the study of PIM mechanisms and the location/suppression of PIM sources.PIM probes,made of open-ended coaxial transmission lines,have almost the same coupling strength to carriers and PIM products,and are usually used for near-field PIM characterization.Namely,it doesn’t have any filtering capability.Therefore,it cannot stop the carrier power from entering into PIM tester’s receiver,which may trigger active intermodulation of the receiver and degrade the PIM tester’s performance.To overcome this drawback,a passive filtering coaxial probe is proposed here.Compared with existing passive coaxial PIM probes,it has stronger coupling strength for PIM products than for carriers.Thus,the probe itself can block part of the carrier power entering into the PIM tester’s receiver.This advantage helps improve PIM tester’s overall performance.Both theoretical analysis and experiments are conducted for demonstration.The proposed probe brings more possibility to PIM characterization.
基金supported by the Karlsruhe School of Optics and Photonics(KSOP)support from the Carl Zeiss foundationsupport by Deutsche Forschungsgemeinschaft and the Open Access Publishing Fund of the Karlsruhe Institute of Technology.
文摘Optical micro-resonators have broad applications.They are used,for example,to enhance light–matter interactions in optical sensors or as model systems for investigating fundamental physical mechanisms in cavity quantum electrodynamics.Coupling two or more micro-cavities is particularly interesting as it enlarges the design freedom and the field of application.In this context,achieving tunability of the coupling strength and hence the inter-cavity gap is of utmost importance for adjusting the properties of the coupled micro-resonator system.In this paper,we report on a novel coupling approach that allows highly precise tuning of the coupling gap of polymeric micro-resonators that are fabricated side by side on a common substrate.We structure goblet-shaped whispering-gallery-mode resonators on an elastic silicone-based polymer substrate by direct laser writing.The silicone substrate is mechanically stretched in order to exploit the lateral shrinkage to reduce the coupling gap.Incorporating a laser dye into the micro-resonators transforms the cavities into micro-lasers that can be pumped optically.We have investigated the lasing emission by micro-photoluminescence spectroscopy,focusing on the spatial localization of the modes.Our results demonstrate the formation of photonic molecules consisting of two or even three resonators,for which the coupling strengths and hence the lasing performance can be precisely tuned.Flexibility and tunability are key elements in future photonics,making our approach interesting for various photonic applications.For instance,as our coupling approach can also be extended to larger cavity arrays,it might serve as a platform for tunable coupled-resonator optical waveguide devices.
