We propose a design and optimization for directional coupling in terahertz hybrid-cladding hollow waveguide. It is composed of two square hollow waveguides which touch each other and are surrounded by a metallic layer...We propose a design and optimization for directional coupling in terahertz hybrid-cladding hollow waveguide. It is composed of two square hollow waveguides which touch each other and are surrounded by a metallic layer. By employing the finite element method, the coupling performance and loss property are numerically investigated. Numerical results indi- cate that this directional coupler with hybrid-cladding can realize ultra-narrow-band coupling; it provides a low confinement loss performance： the confinement loss can reach as low as 6.27 × 10-5 cm- 1. Moreover, the further analyses of configura- tion and performance show that confinement loss and frequency range shift for the low-confinement-loss frequency regime can be realized and optimized by appropriately tuning the thickness values of the metallic and dielectric layer. In addition, through the further analysis of coupling performance, the possibilities of realizing ultra-narrow-band couplings in different frequency ranges are demonstrated. It is a powerful candidate for high precision optical fiber sensing, and communication in terahertz splitting fields.展开更多
This paper reports that an output window for optically pumped terahertz （THz） laser has been fabricated by depositing a capacitive nickel-mesh on a thick high-resistivity silicon substrate （approximating to 5 mm th...This paper reports that an output window for optically pumped terahertz （THz） laser has been fabricated by depositing a capacitive nickel-mesh on a thick high-resistivity silicon substrate （approximating to 5 mm thick）. Unlike the conventional process of depositing a gold film approximating to 100 nm on negative photoresist using electron-beam evaporation, a nickel film approximating to 1.5 μm thick is directly deposited on the clean surface of dielectric substrate using magnetron sputtering and then a positive photoresist is spun onto the nickel metal surface at 6000 r for 60 s. A transmittance spectrum of the output window in a certain frequency range （say, from zero to 1 THz） has been obtained by using THz time domain spectroscopy. Moreover a transmittance spectrum simulated numerically has also been estimated with respect to the output window using the transmission-line model （TLM） containing attenuation component from dielectric substrate. The simulation results show that the TLM can explain well the experimental curve in a certain frequency range from zero to 1 THz. Thus it is demonstrated that the improved optical component can be efficiently used as both output coupler and output window for optically pumped THz lasers.展开更多
设计了一种结构紧凑、工作频带较宽、耦合平稳、高方向性的"十字形"多孔耦合的太赫兹波导定向耦合器。基于多孔耦合原理,利用HFSS软件对太赫兹波导定向耦合器进行了模型仿真和结构优化。仿真结果表明:在325~475 GHz带宽范围内...设计了一种结构紧凑、工作频带较宽、耦合平稳、高方向性的"十字形"多孔耦合的太赫兹波导定向耦合器。基于多孔耦合原理,利用HFSS软件对太赫兹波导定向耦合器进行了模型仿真和结构优化。仿真结果表明:在325~475 GHz带宽范围内,该多孔耦合太赫兹波导定向耦合器耦合度达到7.5±0.8 d B,隔离度达到30 d B,即方向性优于20 d B,各端口回波损耗小于-20 d B。通过对该波导定向耦合器进行高温高压模拟仿真,确定了使用负性光刻胶SU-8作为结构材料的可行性,提出应用MEMS工艺在硅衬底上进行加工,将牺牲层工艺应用到波导腔结构的制作中。利用光刻在直通波导和耦合波导公共宽壁上形成的"十字形"等间距排列耦合孔结构,可以实现较宽的带宽和良好的耦合平坦度。该方法提高了耦合孔尺寸和位置的精度,减小了反射损耗,为太赫兹波导结构的加工提供了新思路。展开更多
设计了一种宽频带、高方向性、耦合平稳的方孔耦合型太赫兹波导定向耦合器。基于多孔耦合原理,用13组小孔来实现宽频带,耦合孔正方形等差减小等间距排列来实现高方向性和较好耦合平坦性。通过HFSS软件对该耦合器进行模型仿真及优化,结...设计了一种宽频带、高方向性、耦合平稳的方孔耦合型太赫兹波导定向耦合器。基于多孔耦合原理,用13组小孔来实现宽频带,耦合孔正方形等差减小等间距排列来实现高方向性和较好耦合平坦性。通过HFSS软件对该耦合器进行模型仿真及优化,结果表明,在0.3~0.5 THz频段内,各端口回波损耗均小于-26 d B,耦合度为(7.8±0.6)d B,属于强耦合且耦合度平坦性良好,隔离度达到30 d B以上,即方向性较好且优于20 d B,平均插入损耗为0.7 d B,相对带宽达到45%。对基于MEMS技术的该耦合器的工艺制作流程进行了阐述,可利用该方法进行加工。展开更多
基金Project supported by the Specific Scientific and Technological Cooperation between China and Russia(Grant No.2010DFR80140)the National Natural Science Foundation of China(Grant No.51309059)
文摘We propose a design and optimization for directional coupling in terahertz hybrid-cladding hollow waveguide. It is composed of two square hollow waveguides which touch each other and are surrounded by a metallic layer. By employing the finite element method, the coupling performance and loss property are numerically investigated. Numerical results indi- cate that this directional coupler with hybrid-cladding can realize ultra-narrow-band coupling; it provides a low confinement loss performance： the confinement loss can reach as low as 6.27 × 10-5 cm- 1. Moreover, the further analyses of configura- tion and performance show that confinement loss and frequency range shift for the low-confinement-loss frequency regime can be realized and optimized by appropriately tuning the thickness values of the metallic and dielectric layer. In addition, through the further analysis of coupling performance, the possibilities of realizing ultra-narrow-band couplings in different frequency ranges are demonstrated. It is a powerful candidate for high precision optical fiber sensing, and communication in terahertz splitting fields.
基金Project supported by the Creative Foundation of Wuhan National Laboratory for Optoelectronics (Grant No. Z080007)partly by the National Basic Research Program of China (973 Program)(Grant No. 61328)
文摘This paper reports that an output window for optically pumped terahertz （THz） laser has been fabricated by depositing a capacitive nickel-mesh on a thick high-resistivity silicon substrate （approximating to 5 mm thick）. Unlike the conventional process of depositing a gold film approximating to 100 nm on negative photoresist using electron-beam evaporation, a nickel film approximating to 1.5 μm thick is directly deposited on the clean surface of dielectric substrate using magnetron sputtering and then a positive photoresist is spun onto the nickel metal surface at 6000 r for 60 s. A transmittance spectrum of the output window in a certain frequency range （say, from zero to 1 THz） has been obtained by using THz time domain spectroscopy. Moreover a transmittance spectrum simulated numerically has also been estimated with respect to the output window using the transmission-line model （TLM） containing attenuation component from dielectric substrate. The simulation results show that the TLM can explain well the experimental curve in a certain frequency range from zero to 1 THz. Thus it is demonstrated that the improved optical component can be efficiently used as both output coupler and output window for optically pumped THz lasers.
文摘设计了一种结构紧凑、工作频带较宽、耦合平稳、高方向性的"十字形"多孔耦合的太赫兹波导定向耦合器。基于多孔耦合原理,利用HFSS软件对太赫兹波导定向耦合器进行了模型仿真和结构优化。仿真结果表明:在325~475 GHz带宽范围内,该多孔耦合太赫兹波导定向耦合器耦合度达到7.5±0.8 d B,隔离度达到30 d B,即方向性优于20 d B,各端口回波损耗小于-20 d B。通过对该波导定向耦合器进行高温高压模拟仿真,确定了使用负性光刻胶SU-8作为结构材料的可行性,提出应用MEMS工艺在硅衬底上进行加工,将牺牲层工艺应用到波导腔结构的制作中。利用光刻在直通波导和耦合波导公共宽壁上形成的"十字形"等间距排列耦合孔结构,可以实现较宽的带宽和良好的耦合平坦度。该方法提高了耦合孔尺寸和位置的精度,减小了反射损耗,为太赫兹波导结构的加工提供了新思路。
文摘设计了一种宽频带、高方向性、耦合平稳的方孔耦合型太赫兹波导定向耦合器。基于多孔耦合原理,用13组小孔来实现宽频带,耦合孔正方形等差减小等间距排列来实现高方向性和较好耦合平坦性。通过HFSS软件对该耦合器进行模型仿真及优化,结果表明,在0.3~0.5 THz频段内,各端口回波损耗均小于-26 d B,耦合度为(7.8±0.6)d B,属于强耦合且耦合度平坦性良好,隔离度达到30 d B以上,即方向性较好且优于20 d B,平均插入损耗为0.7 d B,相对带宽达到45%。对基于MEMS技术的该耦合器的工艺制作流程进行了阐述,可利用该方法进行加工。
基金Supported by National Instrumentation Program(2012YQ140005)Nature Science Foundation of Beijing(4144069)Science and Technology Project of Beijing Municipal Education Commission(KM201410028004)
