Compared with well-developed free space polarization converters, polarization conversion between TE and TM modes in the waveguide is generally considered to be caused by shape birefringence, like curvature, morphology...Compared with well-developed free space polarization converters, polarization conversion between TE and TM modes in the waveguide is generally considered to be caused by shape birefringence, like curvature, morphology of waveguide cross section and scattering. Here, we study the polarization conversion mechanism in 1-THz-FSR X-cut lithium niobate microrings with multiple-resonance condition, that is the conversion can be implemented by birefringence of waveguides,which will also introduce an avoided-mode crossing. In the experiment, we find that this mode crossing results in severe suppression of one sideband in local nondegenerate four-wave mixing and disrupts the cascaded four-wave mixing on this side. Simultaneously, we propose one two-dimensional method to simulate the eigenmodes(TE and TM) in X-cut microrings, and the mode crossing point. This work will provide one approach to the design of polarization converters and simulation for monolithic photonics integrated circuits, and may be helpful to the studies of missed temporal dissipative soliton formation in X-cut lithium niobate rings.展开更多
As a natural analog of resveratrol,piceatannol(Pic)exhibits good antioxidant and anti-inflammatory activities in different disease models.However,the role of Pic in type 1 diabetes mousemodel has not been reported yet...As a natural analog of resveratrol,piceatannol(Pic)exhibits good antioxidant and anti-inflammatory activities in different disease models.However,the role of Pic in type 1 diabetes mousemodel has not been reported yet.In this study,we investigated the in vivo effect of Pic in streptozotocin(STZ)-induced type 1 diabetic mice.Mice were injected with STZ to establish the type 1 diabetesmellitus(T1DM)model.After stable hyperglycemia was achieved,mice were then orally treated with Pic(40 mg/kg b.w.,i.g.)for 30 days.The results indicated that Pic supplementation efficiently alleviated the typical symptoms associated with T1DM,including body weight loss,polydipsia,hyperglycemia,and hypoinsulinemia.Pic treatment also improved the glucose tolerance of STZ-induced diabetic mice.In addition,Pic supplementation markedly decreased the expression of pro-inflammatory molecules TNF-αand IL-6,the expression of endoplasmic reticulum(ER)stress markers GRP78 and CHOP,and the level of oxidative stress in T1DM mice.Moreover,Pic administration also partly reversed the metabolic profiles of STZ-treated mice as detected by 1H Nuclear Magnetic Resonance(NMR)-based metabolomics.Our study suggested that the therapeutic potential of Pic in type 1 diabetes and the anti-diabetic effects of Pic may be associated with its activities to suppress oxidative stress,inflammation,and ER stress.展开更多
According to the fundamental Huygens superposition principle,light beams traveling in a linear medium will pass though one another without mutual disturbance.Indeed,the field of photonics is based on the premise that ...According to the fundamental Huygens superposition principle,light beams traveling in a linear medium will pass though one another without mutual disturbance.Indeed,the field of photonics is based on the premise that controlling light signals with light requires intense laser fields to facilitate beam interactions in nonlinear media,where the superposition principle can be broken.Here we challenge this wisdom and demonstrate that two coherent beams of light of arbitrarily low intensity can interact on a metamaterial layer of nanoscale thickness in such a way that one beam modulates the intensity of the other.We show that the interference of beams can eliminate the plasmonic Joule losses of light energy in the metamaterial or,in contrast,can lead to almost total absorption of light.Applications of this phenomenon may lie in ultrafast all-optical pulse-recovery devices,coherence filters and terahertz-bandwidth light-by-light modulators.展开更多
We introduce a dielectric photonic metamaterial presenting a giant nonlinear optical response driven by resonant optomechanical forces.Being inherently free of Joule losses,it exhibits optical bistability at intensity...We introduce a dielectric photonic metamaterial presenting a giant nonlinear optical response driven by resonant optomechanical forces.Being inherently free of Joule losses,it exhibits optical bistability at intensity levels of less than 0.2 mW mm22 and,furthermore,manifests nonlinear asymmetric transmission with a forward:backward optical extinction ratio of more than 30 dB.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12274462 and 11674396)the Department of Science and Technology of Hunan Province of China (Grant Nos. 2017RS3039 and 2018JJ1033)the Hunan Provincial Innovation Foundation for Postgraduate of China (Grant No. QL20210006)。
文摘Compared with well-developed free space polarization converters, polarization conversion between TE and TM modes in the waveguide is generally considered to be caused by shape birefringence, like curvature, morphology of waveguide cross section and scattering. Here, we study the polarization conversion mechanism in 1-THz-FSR X-cut lithium niobate microrings with multiple-resonance condition, that is the conversion can be implemented by birefringence of waveguides,which will also introduce an avoided-mode crossing. In the experiment, we find that this mode crossing results in severe suppression of one sideband in local nondegenerate four-wave mixing and disrupts the cascaded four-wave mixing on this side. Simultaneously, we propose one two-dimensional method to simulate the eigenmodes(TE and TM) in X-cut microrings, and the mode crossing point. This work will provide one approach to the design of polarization converters and simulation for monolithic photonics integrated circuits, and may be helpful to the studies of missed temporal dissipative soliton formation in X-cut lithium niobate rings.
基金the National Natural Science Foundation of China under Grant 21677076 and 31970897 to DWOutstanding Youth Foundation of Jiangsu Province(BK20190093)to DWQing Lan Project of Jiangsu Province to DW,the Fundamental Research Funds for the Central Universities No.30919011102 to DW,the Innovative and Entrepreneurial Talent Cultivation(Shuangchuang)Program of Jiangsu Province to DW.
文摘As a natural analog of resveratrol,piceatannol(Pic)exhibits good antioxidant and anti-inflammatory activities in different disease models.However,the role of Pic in type 1 diabetes mousemodel has not been reported yet.In this study,we investigated the in vivo effect of Pic in streptozotocin(STZ)-induced type 1 diabetic mice.Mice were injected with STZ to establish the type 1 diabetesmellitus(T1DM)model.After stable hyperglycemia was achieved,mice were then orally treated with Pic(40 mg/kg b.w.,i.g.)for 30 days.The results indicated that Pic supplementation efficiently alleviated the typical symptoms associated with T1DM,including body weight loss,polydipsia,hyperglycemia,and hypoinsulinemia.Pic treatment also improved the glucose tolerance of STZ-induced diabetic mice.In addition,Pic supplementation markedly decreased the expression of pro-inflammatory molecules TNF-αand IL-6,the expression of endoplasmic reticulum(ER)stress markers GRP78 and CHOP,and the level of oxidative stress in T1DM mice.Moreover,Pic administration also partly reversed the metabolic profiles of STZ-treated mice as detected by 1H Nuclear Magnetic Resonance(NMR)-based metabolomics.Our study suggested that the therapeutic potential of Pic in type 1 diabetes and the anti-diabetic effects of Pic may be associated with its activities to suppress oxidative stress,inflammation,and ER stress.
基金The authors thank Jun-Yu Ou and Mengxin Ren for assistance with nanofabrication and optical experiments respectively.This work was supported by the Engineering and Physical Sciences Research Council(grant EP/G060363/1),The Royal Society and the China Scholarship Council.
文摘According to the fundamental Huygens superposition principle,light beams traveling in a linear medium will pass though one another without mutual disturbance.Indeed,the field of photonics is based on the premise that controlling light signals with light requires intense laser fields to facilitate beam interactions in nonlinear media,where the superposition principle can be broken.Here we challenge this wisdom and demonstrate that two coherent beams of light of arbitrarily low intensity can interact on a metamaterial layer of nanoscale thickness in such a way that one beam modulates the intensity of the other.We show that the interference of beams can eliminate the plasmonic Joule losses of light energy in the metamaterial or,in contrast,can lead to almost total absorption of light.Applications of this phenomenon may lie in ultrafast all-optical pulse-recovery devices,coherence filters and terahertz-bandwidth light-by-light modulators.
基金This work was supported by the Engineering and Physical Sciences Research Council(grant EP/G060363/1)[All authors]the Royal Society and the Ministry of Education,Singapore(grant MOE2011-T3-1-005)[NIZ]the China Scholarship Council[JZ].
文摘We introduce a dielectric photonic metamaterial presenting a giant nonlinear optical response driven by resonant optomechanical forces.Being inherently free of Joule losses,it exhibits optical bistability at intensity levels of less than 0.2 mW mm22 and,furthermore,manifests nonlinear asymmetric transmission with a forward:backward optical extinction ratio of more than 30 dB.
