The Mueller matrix polar decomposition method decomposes a Mueller matrix into a diattenuator,a retarder,and a depolarizer.Among these elements,the retarder,which plays a key role in medical and material characterizat...The Mueller matrix polar decomposition method decomposes a Mueller matrix into a diattenuator,a retarder,and a depolarizer.Among these elements,the retarder,which plays a key role in medical and material characterization,is usually modelled as a circular retarder followed by a linear retarder.However,this model may not accurately reflect the actual structure of the retarder in certain cases as many practical retarders do not have a layered structure or consist of multiple(unknown)layers.Misinterpretation,therefore,may occur when the actual structure differs from the model.Here,we circumvent this limitation by proposing to use an elliptical retarder parameter set that includes the axis orientation angleφ,the degree of ellipticityχ,and the elliptical retardanceρ.By working with this set of parameters,an overall characterization of any retarder is provided,encompassing its full optical response without making any assumptions about the structure of the material.In this study,experiments were carried out on liquid crystalline samples to validate the feasibility of our approach,demonstrating that the elliptical retarder parameter set adopted provides a useful tool for a broader range of applications in optical material analysis.展开更多
Mode-locked microcombs with flat spectral profiles provide the high signal-to-noise ratio and are in high demand for wavelength division multiplexing(WDM)-based applications,particularly in future high-capacity commun...Mode-locked microcombs with flat spectral profiles provide the high signal-to-noise ratio and are in high demand for wavelength division multiplexing(WDM)-based applications,particularly in future high-capacity communication and parallel optical computing.Here,we present two solutions to generate local relatively flat spectral profiles.One microcavity with ultra-flat integrated dispersion is pumped to generate one relatively flat single soliton source spanning over 150 nm.Besides,one extraordinary soliton crystal with single vacancy demonstrates the local relatively flat microcomb lines when the inner soliton spacings are slightly irregular.Our work paves a new way for soliton-based applications owing to the relatively flat spectral characteristics.展开更多
With the development of conformable photonic platforms,particularly those that could be interfaced with the human body or integrated into wearable technology,there is an ever-increasing need for mechanically flexible ...With the development of conformable photonic platforms,particularly those that could be interfaced with the human body or integrated into wearable technology,there is an ever-increasing need for mechanically flexible optical photonic elements in soft materials.Here,we realize mechanically flexible liquid crystal(LC)waveguides using a combination of ultrafast direct laser writing and ultraviolet(UV)photo-polymerization.Results are presented that demonstrate that these laser-written waveguides can be either electrically switchable(by omitting the bulk UV polymerization step)or mechanically flexible.Characteristics of the waveguide are investigated for different fabrication conditions and geometrical configurations,including the dimensions of the waveguide and laser writing power.Our findings reveal that smaller waveguide geometries result in reduced intensity attenuation.Specifically,for a 10-μm-wide laser-written channel in a 14-μm-thick LC layer,a loss factor of-1.8 dB/mm atλ=650 nm was observed.Following the UV polymerization step and subsequent delamination of the glass substrates,we demonstrate a free-standing flexible LC waveguide,which retains waveguide functionality even when bent,making it potentially suitable for on-skin sensors and other photonic devices that could interface with the human body.For the flexible LC waveguides fabricated in this study,the loss in a straight waveguide with a cross-sectional area of 20μm×20μm was recorded to be-0.2 dB/mm.These results highlight the promising potential of electrically responsive and mechanically moldable optical waveguides using laser writing and UV-assisted polymer network formation.展开更多
基金support of St John’s College,the University of Oxford,and the Royal Society(Grant No.URF\R1\241734)(C.H.).
文摘The Mueller matrix polar decomposition method decomposes a Mueller matrix into a diattenuator,a retarder,and a depolarizer.Among these elements,the retarder,which plays a key role in medical and material characterization,is usually modelled as a circular retarder followed by a linear retarder.However,this model may not accurately reflect the actual structure of the retarder in certain cases as many practical retarders do not have a layered structure or consist of multiple(unknown)layers.Misinterpretation,therefore,may occur when the actual structure differs from the model.Here,we circumvent this limitation by proposing to use an elliptical retarder parameter set that includes the axis orientation angleφ,the degree of ellipticityχ,and the elliptical retardanceρ.By working with this set of parameters,an overall characterization of any retarder is provided,encompassing its full optical response without making any assumptions about the structure of the material.In this study,experiments were carried out on liquid crystalline samples to validate the feasibility of our approach,demonstrating that the elliptical retarder parameter set adopted provides a useful tool for a broader range of applications in optical material analysis.
基金funding support from Dream X International Innovation Teamthe support from the startup grant from Nanyang Technological University (022527-00001)。
文摘Mode-locked microcombs with flat spectral profiles provide the high signal-to-noise ratio and are in high demand for wavelength division multiplexing(WDM)-based applications,particularly in future high-capacity communication and parallel optical computing.Here,we present two solutions to generate local relatively flat spectral profiles.One microcavity with ultra-flat integrated dispersion is pumped to generate one relatively flat single soliton source spanning over 150 nm.Besides,one extraordinary soliton crystal with single vacancy demonstrates the local relatively flat microcomb lines when the inner soliton spacings are slightly irregular.Our work paves a new way for soliton-based applications owing to the relatively flat spectral characteristics.
基金funded in whole,or in part,by the UKRI(EP/R004803/01,P.S.S.,EP/R511742/1,S.M.M.,S.J.E.,and M.J.B.)。
文摘With the development of conformable photonic platforms,particularly those that could be interfaced with the human body or integrated into wearable technology,there is an ever-increasing need for mechanically flexible optical photonic elements in soft materials.Here,we realize mechanically flexible liquid crystal(LC)waveguides using a combination of ultrafast direct laser writing and ultraviolet(UV)photo-polymerization.Results are presented that demonstrate that these laser-written waveguides can be either electrically switchable(by omitting the bulk UV polymerization step)or mechanically flexible.Characteristics of the waveguide are investigated for different fabrication conditions and geometrical configurations,including the dimensions of the waveguide and laser writing power.Our findings reveal that smaller waveguide geometries result in reduced intensity attenuation.Specifically,for a 10-μm-wide laser-written channel in a 14-μm-thick LC layer,a loss factor of-1.8 dB/mm atλ=650 nm was observed.Following the UV polymerization step and subsequent delamination of the glass substrates,we demonstrate a free-standing flexible LC waveguide,which retains waveguide functionality even when bent,making it potentially suitable for on-skin sensors and other photonic devices that could interface with the human body.For the flexible LC waveguides fabricated in this study,the loss in a straight waveguide with a cross-sectional area of 20μm×20μm was recorded to be-0.2 dB/mm.These results highlight the promising potential of electrically responsive and mechanically moldable optical waveguides using laser writing and UV-assisted polymer network formation.
