Coupling efficiency between the localized surface plasmons(LSPs) of metal nanoparticles(NPs) and incident light dominates the sensitivities of plasmon-based sensing spectroscopies and imaging techniques, e.g., surface...Coupling efficiency between the localized surface plasmons(LSPs) of metal nanoparticles(NPs) and incident light dominates the sensitivities of plasmon-based sensing spectroscopies and imaging techniques, e.g., surfaceenhanced Raman scattering(SERS) spectroscopy. Many endogenous features of metal NPs(e.g., size, shape,aggregation form, etc.) that have strong impacts on their LSPs have been discussed in detail in previous studies.Here, the polarization-tuned electromagnetic(EM) field that facilitates the LSP coupling is fully discussed.Numerical analyses on waveguide-based evanescent fields(WEFs) coupled with the LSPs of dispersed silver nanospheres and silver nano-hemispheres are presented and the applicability of the WEF-LSPs to plasmon-enhanced spectroscopy is discussed. Compared with LSPs under direct light excitation that only provide 3–4 times enhancement of the incidence field, the WEF-LSPs can amplify the electric field intensity about 30–90 times(equaling the enhancement factor of 10~6–10~8 in SERS intensity), which is comparable to the EM amplification of the SERS"hot spot" effect. Importantly, the strongest region of EM enhancement around silver nanospheres can be modulated from the gap region to the side surface simply by switching the incident polarization from TM to TE, which widely extends its sensing applications in surface analysis of monolayer of molecule and macromolecule detections. This technique provides us a unique way to achieve remarkable signal gains in many plasmon-enhanced spectroscopic systems in which LSPs are involved.展开更多
In this review,we introduce some chip-based waveguide biosensing and imaging techniques,which significantly reduce the complexity of the entire system.These techniques use a well-confined evanescent field to interact ...In this review,we introduce some chip-based waveguide biosensing and imaging techniques,which significantly reduce the complexity of the entire system.These techniques use a well-confined evanescent field to interact with the surrounding materials and achieve high sensitivity sensing and high signal-to-noise ratio(SNR)super-resolution imaging.The fabrication process of these chips is simple and compatible with conventional semiconductor fabrication methods,allowing high-yield production.Combined with recently developed chip-based light sources,these techniques offer the possibility of biosensing and super-resolution imaging based on integrated circuits.展开更多
This paper presents progress on the characterization of guided-wave light modulators for use in a low-cost holographic video monitor based on the MIT scanned-aperture architecture. A custom-built characterization appa...This paper presents progress on the characterization of guided-wave light modulators for use in a low-cost holographic video monitor based on the MIT scanned-aperture architecture. A custom-built characterization apparatus was used to study device bandwidth, RGB operation, and linearity in an effort to identify optimal parameters for high bandwidth, GPU-driven, full-color holographic display.展开更多
We propose a novel silicon optical phase shifter structure based on heterogeneous strip-loaded waveguides on a photonic silicon on insulator(SOI) platform. The features of an etchless SOI layer and loaded strip would ...We propose a novel silicon optical phase shifter structure based on heterogeneous strip-loaded waveguides on a photonic silicon on insulator(SOI) platform. The features of an etchless SOI layer and loaded strip would enhance the performance and uniformity of silicon optical modulators on a large-scale wafer. We implemented the phase shifter by loading an amorphous silicon strip onto an SOI layer with a vertical PN diode structure. Compared to the conventional lateral PN phase shifter based on half-etched rib waveguides, this phase shifter shows a >1.5 times enhancement of modulation efficiency and provides >20 GHz high-speed operation.展开更多
A CO2 sensor for capnography, based on a hollow waveguide(HWG) and tunable diode laser absorption spectroscopy(TDLAS), is presented; the sensor uses direct absorption spectroscopy and requires neither frequent calibra...A CO2 sensor for capnography, based on a hollow waveguide(HWG) and tunable diode laser absorption spectroscopy(TDLAS), is presented; the sensor uses direct absorption spectroscopy and requires neither frequent calibration nor optical filters, giving it a significant advantage over existing techniques. Because of the HWG, the CO2 measurement achieved a concentration resolution of 60 ppm at a measurement rate of 25 Hz, as characterized by Allan variance. The length of the HWG was selected to efficiently suppress the optical fringes. This setup is perfectly suited for the detection of CO2 by capnography, and shows promise for the potential detection of other breath gases.展开更多
渐变鳍线阵在空间功率合成放大器中具有重要的应用价值。该文简化渐变鳍线阵的模型,将渐变鳍线阵设计等效为TE模式波阻抗的渐变阻抗变换,采用谱域导纳法计算渐变鳍线阵的传播常数,依据小反射理论,提出一种新型基于Hecken形式的紧凑、宽...渐变鳍线阵在空间功率合成放大器中具有重要的应用价值。该文简化渐变鳍线阵的模型,将渐变鳍线阵设计等效为TE模式波阻抗的渐变阻抗变换,采用谱域导纳法计算渐变鳍线阵的传播常数,依据小反射理论,提出一种新型基于Hecken形式的紧凑、宽带渐变鳍线阵。利用高频仿真软件HFSS进行优化仿真设计,通过引入槽线微带过渡电路,实际加工了X波段2×2鳍线阵,背靠背测试结果表明：在X波段（8~12 GHz）内,反射系数小于-12d B,插入损耗小于1 d B,实测结果与理论计算吻合。该文系统地给出渐变鳍线阵设计优化的理论计算和仿真方法,对基于波导内空间功率合成模块设计具有指导意义,具有良好的工程应用前景。展开更多
A mode transformer based on the quasi-vertical taper is designed to enable high coupling efficiency for interboardlevel optical interconnects involving single-mode polymer waveguides and standard single-mode fibers. A...A mode transformer based on the quasi-vertical taper is designed to enable high coupling efficiency for interboardlevel optical interconnects involving single-mode polymer waveguides and standard single-mode fibers. A triangular region fabricated above the waveguide is adopted to adiabatically transform the mode from the fiber into the polymer waveguide. The effects of the geometrical parameters of the taper, including width, height, tip width,etc., on the coupling efficiency are numerically investigated. Based on this, a quasi-vertical taper for the polymer rib waveguide system is designed, fabricated, and characterized. Coupling losses of 1.79 0.30 and 2.23 0.31 dB per coupler for the quasi-TM and quasi-TE mode, respectively, are measured across the optical communication C and L bands(1535 to 1610 nm). Low-cost packaging, leading to widespread utilization of polymeric photonicdevices, is envisioned for optical interconnect applications.展开更多
基金National Natural Science Foundation of China(NSFC)(21373096,21573087,21573092,91441105)National Instrumentation Program(NIP)of the Ministry of Science and Technology of the People’s Republic of China(MOST)(2011YQ03012408)Science and Technology Development Program Funded Projects of Jilin Province
文摘Coupling efficiency between the localized surface plasmons(LSPs) of metal nanoparticles(NPs) and incident light dominates the sensitivities of plasmon-based sensing spectroscopies and imaging techniques, e.g., surfaceenhanced Raman scattering(SERS) spectroscopy. Many endogenous features of metal NPs(e.g., size, shape,aggregation form, etc.) that have strong impacts on their LSPs have been discussed in detail in previous studies.Here, the polarization-tuned electromagnetic(EM) field that facilitates the LSP coupling is fully discussed.Numerical analyses on waveguide-based evanescent fields(WEFs) coupled with the LSPs of dispersed silver nanospheres and silver nano-hemispheres are presented and the applicability of the WEF-LSPs to plasmon-enhanced spectroscopy is discussed. Compared with LSPs under direct light excitation that only provide 3–4 times enhancement of the incidence field, the WEF-LSPs can amplify the electric field intensity about 30–90 times(equaling the enhancement factor of 10~6–10~8 in SERS intensity), which is comparable to the EM amplification of the SERS"hot spot" effect. Importantly, the strongest region of EM enhancement around silver nanospheres can be modulated from the gap region to the side surface simply by switching the incident polarization from TM to TE, which widely extends its sensing applications in surface analysis of monolayer of molecule and macromolecule detections. This technique provides us a unique way to achieve remarkable signal gains in many plasmon-enhanced spectroscopic systems in which LSPs are involved.
基金the National Natural Science Foundation of China(Nos.61735017,61822510,and 51672245)the Zhejiang Provincial Natural Science Foundation of China(No.R17F050003)+4 种基金the National Key Basic Research Program of China(No.2015CB352003)the Fundamental Research Funds for the Central Universities,Chinathe Program for Zhejiang Leading Team of S&T Innovationthe Cao Guangbiao Advanced Technology Programthe First-Class Universities and Academic Programs。
文摘In this review,we introduce some chip-based waveguide biosensing and imaging techniques,which significantly reduce the complexity of the entire system.These techniques use a well-confined evanescent field to interact with the surrounding materials and achieve high sensitivity sensing and high signal-to-noise ratio(SNR)super-resolution imaging.The fabrication process of these chips is simple and compatible with conventional semiconductor fabrication methods,allowing high-yield production.Combined with recently developed chip-based light sources,these techniques offer the possibility of biosensing and super-resolution imaging based on integrated circuits.
基金supported by the Air Force Research Laboratory contract FA8650-14-C-6571
文摘This paper presents progress on the characterization of guided-wave light modulators for use in a low-cost holographic video monitor based on the MIT scanned-aperture architecture. A custom-built characterization apparatus was used to study device bandwidth, RGB operation, and linearity in an effort to identify optimal parameters for high bandwidth, GPU-driven, full-color holographic display.
文摘We propose a novel silicon optical phase shifter structure based on heterogeneous strip-loaded waveguides on a photonic silicon on insulator(SOI) platform. The features of an etchless SOI layer and loaded strip would enhance the performance and uniformity of silicon optical modulators on a large-scale wafer. We implemented the phase shifter by loading an amorphous silicon strip onto an SOI layer with a vertical PN diode structure. Compared to the conventional lateral PN phase shifter based on half-etched rib waveguides, this phase shifter shows a >1.5 times enhancement of modulation efficiency and provides >20 GHz high-speed operation.
基金supported by the Special-funded Program on National Key Scientific Instruments and Equipment Development of China(No.2012YQ06016501)the Tianjin Natural Science Fund Project(No.11JCYBJC04900)
文摘A CO2 sensor for capnography, based on a hollow waveguide(HWG) and tunable diode laser absorption spectroscopy(TDLAS), is presented; the sensor uses direct absorption spectroscopy and requires neither frequent calibration nor optical filters, giving it a significant advantage over existing techniques. Because of the HWG, the CO2 measurement achieved a concentration resolution of 60 ppm at a measurement rate of 25 Hz, as characterized by Allan variance. The length of the HWG was selected to efficiently suppress the optical fringes. This setup is perfectly suited for the detection of CO2 by capnography, and shows promise for the potential detection of other breath gases.
文摘渐变鳍线阵在空间功率合成放大器中具有重要的应用价值。该文简化渐变鳍线阵的模型,将渐变鳍线阵设计等效为TE模式波阻抗的渐变阻抗变换,采用谱域导纳法计算渐变鳍线阵的传播常数,依据小反射理论,提出一种新型基于Hecken形式的紧凑、宽带渐变鳍线阵。利用高频仿真软件HFSS进行优化仿真设计,通过引入槽线微带过渡电路,实际加工了X波段2×2鳍线阵,背靠背测试结果表明：在X波段（8~12 GHz）内,反射系数小于-12d B,插入损耗小于1 d B,实测结果与理论计算吻合。该文系统地给出渐变鳍线阵设计优化的理论计算和仿真方法,对基于波导内空间功率合成模块设计具有指导意义,具有良好的工程应用前景。
基金supported by Air Force Office of Scientific Research (AFOSR) for supporting this work under the Small Business Technology Transfer Research (STTR) program (grant no. FA9550-14-C-0001)
文摘A mode transformer based on the quasi-vertical taper is designed to enable high coupling efficiency for interboardlevel optical interconnects involving single-mode polymer waveguides and standard single-mode fibers. A triangular region fabricated above the waveguide is adopted to adiabatically transform the mode from the fiber into the polymer waveguide. The effects of the geometrical parameters of the taper, including width, height, tip width,etc., on the coupling efficiency are numerically investigated. Based on this, a quasi-vertical taper for the polymer rib waveguide system is designed, fabricated, and characterized. Coupling losses of 1.79 0.30 and 2.23 0.31 dB per coupler for the quasi-TM and quasi-TE mode, respectively, are measured across the optical communication C and L bands(1535 to 1610 nm). Low-cost packaging, leading to widespread utilization of polymeric photonicdevices, is envisioned for optical interconnect applications.
