By stretching the rod waveguide with different velocities in opposite directions,the tapered waveguide can be fabricated.In condition of taking no account of volume expansion caused by heating and under the assumption...By stretching the rod waveguide with different velocities in opposite directions,the tapered waveguide can be fabricated.In condition of taking no account of volume expansion caused by heating and under the assumptions of volume conservation,the rod waveguide can be stretched freely in the heated region without being stretched outside of the heated region. A model,which shows the relation of the transition shape and the two factors,that is the ratio of two velocity and the heated region length,is presented for the shape of the taper transition through mathematic deduction.Based on this model,a desired tapered waveguide can be fabricated.The tapered waveguide are widely used for fabricating tapered fiber couplers and sensors.In addition,the conclusion can be used for fabricating fused fiber coupler.展开更多
In earlier approach, the 2-D acoustical field profiles on the substrate region are often calculated with BPM. In this paper, we present a new approach based on the finite element -artificial transmitting boundary meth...In earlier approach, the 2-D acoustical field profiles on the substrate region are often calculated with BPM. In this paper, we present a new approach based on the finite element -artificial transmitting boundary method and calculate acoustical field on the substrate region.展开更多
A novel structure of spot size converter is designed to allow low loss and large alignment tolerance between single mode rib waveguide devices and fiber arrays theoretically.The spot size converter consists of a ta...A novel structure of spot size converter is designed to allow low loss and large alignment tolerance between single mode rib waveguide devices and fiber arrays theoretically.The spot size converter consists of a tapered rib core region and a double cladding region.Through optimizing parameters,an expanded mode field can be tightly confined in the inner cladding and thus radiation loss be reduced largely at the tapered region.The influence of refractive index and thickness of the inner cladding on coupling loss is analyzed in particular.A novel,easy method of fabricating tapered rib spot size converter based on silicon on insulator material is proposed.展开更多
An ultracompact 3 dB coupler is designed and fabricated in silicon on insulator,based on 1×2 line tapered multimode interference (MMI) coupler.Comparing with the conventional straight MMI coupler,the device is...An ultracompact 3 dB coupler is designed and fabricated in silicon on insulator,based on 1×2 line tapered multimode interference (MMI) coupler.Comparing with the conventional straight MMI coupler,the device is ～40% shorter in length.The device exhibits uniformity of 1 3dB and excess loss of 2 5dB.展开更多
Calculations of the TE10 tapered waveguide, which will be used in the 4.6 GHz lower hybrid current drive （LHCD） launcher on the EAST, are presented. The calculations are performed in two ways, namely by directly sol...Calculations of the TE10 tapered waveguide, which will be used in the 4.6 GHz lower hybrid current drive （LHCD） launcher on the EAST, are presented. The calculations are performed in two ways, namely by directly solving the classical coupling wave equations, and by using the simulation code of the high frequency structure simulator （HFSS）. According to the calculations, the voltage standing wave ratio （VSWR） of the designed tapered waveguide can be less than 1.01 within a bandwidth of ±100 MHz.展开更多
A novel S-bend with tapered curved waveguides is proposed. The normalized transmitted power is greater than the conventional bend with weakly guided waveguides. Small size and low loss can be reached by the proposed S...A novel S-bend with tapered curved waveguides is proposed. The normalized transmitted power is greater than the conventional bend with weakly guided waveguides. Small size and low loss can be reached by the proposed S-bend.展开更多
To compensate for the loss of cartier density along the active region of quantum-dot semiconductor optical amplifiers （QD-SOAs）, tapered structure of the waveguide is introduced. In this paper, a method for theoreti...To compensate for the loss of cartier density along the active region of quantum-dot semiconductor optical amplifiers （QD-SOAs）, tapered structure of the waveguide is introduced. In this paper, a method for theoretically modeling of such devices is proposed, and according to that model different shapes of tapered waveguides are studied. This study is pivoted around the optical gain and cross-gain modulation （XGM） of the QD- SOA under investigation to show how altering the shape of the waveguide affects the main characteristics of the device. For doing so, the rate equation model has been employed and solved through finite difference method and MATLAB ODE. Through this, as long as monotonically increasing profiles for the width of the waveguide are used, the shape of the waveguide has a negligible effect on the gain which mainly depends on the width ratio of the waveguide output to its input. However, this carrier compensation has adverse effect on the XGM, where its efficiency rely on how the pump signal can effectively reduce carder density and upset the gain.展开更多
The Compact Pulsed Hadron Source （CPHS） project is a university-based proton accelerator platform （13 MeV,16 kW,50 mA peak current,0.5 ms pulse width at 50 Hz） for multi-disciplinary neutron and proton application...The Compact Pulsed Hadron Source （CPHS） project is a university-based proton accelerator platform （13 MeV,16 kW,50 mA peak current,0.5 ms pulse width at 50 Hz） for multi-disciplinary neutron and proton applications.The CPHS linac consists of a 3 MeV radio-frequency quadrupole （RFQ） linac and a 13 MeV drift tube linac （DTL）.Both the RFQ and DTL share a 325 MHz,2.1 MW klystron source.A single iris-type radio-frequency （RF） coupler is used to feed 537 kW of RF power to the RFQ cavity.Three-dimensional electromagnetic models of the ridge-loaded tapered waveguide （RLWG） and the coupler-cavity system are presented,and the design process and results of the RLWG and iris plate are described in detail.展开更多
文摘By stretching the rod waveguide with different velocities in opposite directions,the tapered waveguide can be fabricated.In condition of taking no account of volume expansion caused by heating and under the assumptions of volume conservation,the rod waveguide can be stretched freely in the heated region without being stretched outside of the heated region. A model,which shows the relation of the transition shape and the two factors,that is the ratio of two velocity and the heated region length,is presented for the shape of the taper transition through mathematic deduction.Based on this model,a desired tapered waveguide can be fabricated.The tapered waveguide are widely used for fabricating tapered fiber couplers and sensors.In addition,the conclusion can be used for fabricating fused fiber coupler.
基金This work was supported by the National Natural Science Fund of China (10084001) the Action Plan for Booming Education of Tianjin University.
文摘In earlier approach, the 2-D acoustical field profiles on the substrate region are often calculated with BPM. In this paper, we present a new approach based on the finite element -artificial transmitting boundary method and calculate acoustical field on the substrate region.
文摘A novel structure of spot size converter is designed to allow low loss and large alignment tolerance between single mode rib waveguide devices and fiber arrays theoretically.The spot size converter consists of a tapered rib core region and a double cladding region.Through optimizing parameters,an expanded mode field can be tightly confined in the inner cladding and thus radiation loss be reduced largely at the tapered region.The influence of refractive index and thickness of the inner cladding on coupling loss is analyzed in particular.A novel,easy method of fabricating tapered rib spot size converter based on silicon on insulator material is proposed.
文摘An ultracompact 3 dB coupler is designed and fabricated in silicon on insulator,based on 1×2 line tapered multimode interference (MMI) coupler.Comparing with the conventional straight MMI coupler,the device is ～40% shorter in length.The device exhibits uniformity of 1 3dB and excess loss of 2 5dB.
文摘Calculations of the TE10 tapered waveguide, which will be used in the 4.6 GHz lower hybrid current drive （LHCD） launcher on the EAST, are presented. The calculations are performed in two ways, namely by directly solving the classical coupling wave equations, and by using the simulation code of the high frequency structure simulator （HFSS）. According to the calculations, the voltage standing wave ratio （VSWR） of the designed tapered waveguide can be less than 1.01 within a bandwidth of ±100 MHz.
文摘A novel S-bend with tapered curved waveguides is proposed. The normalized transmitted power is greater than the conventional bend with weakly guided waveguides. Small size and low loss can be reached by the proposed S-bend.
文摘To compensate for the loss of cartier density along the active region of quantum-dot semiconductor optical amplifiers （QD-SOAs）, tapered structure of the waveguide is introduced. In this paper, a method for theoretically modeling of such devices is proposed, and according to that model different shapes of tapered waveguides are studied. This study is pivoted around the optical gain and cross-gain modulation （XGM） of the QD- SOA under investigation to show how altering the shape of the waveguide affects the main characteristics of the device. For doing so, the rate equation model has been employed and solved through finite difference method and MATLAB ODE. Through this, as long as monotonically increasing profiles for the width of the waveguide are used, the shape of the waveguide has a negligible effect on the gain which mainly depends on the width ratio of the waveguide output to its input. However, this carrier compensation has adverse effect on the XGM, where its efficiency rely on how the pump signal can effectively reduce carder density and upset the gain.
文摘The Compact Pulsed Hadron Source （CPHS） project is a university-based proton accelerator platform （13 MeV,16 kW,50 mA peak current,0.5 ms pulse width at 50 Hz） for multi-disciplinary neutron and proton applications.The CPHS linac consists of a 3 MeV radio-frequency quadrupole （RFQ） linac and a 13 MeV drift tube linac （DTL）.Both the RFQ and DTL share a 325 MHz,2.1 MW klystron source.A single iris-type radio-frequency （RF） coupler is used to feed 537 kW of RF power to the RFQ cavity.Three-dimensional electromagnetic models of the ridge-loaded tapered waveguide （RLWG） and the coupler-cavity system are presented,and the design process and results of the RLWG and iris plate are described in detail.
