A modified alternating direction implicit algorithm is proposed to solve the full-vectorial finite-difference beam propagation method formulation based on H fields. The cross-coupling terms are neglected in the first ...A modified alternating direction implicit algorithm is proposed to solve the full-vectorial finite-difference beam propagation method formulation based on H fields. The cross-coupling terms are neglected in the first sub-step, but evaluated and doubly used in the second sub-step. The order of two sub-steps is reversed for each transverse magnetic field component so that the cross-coupling terms are always expressed in implicit form, thus the calculation is very efficient and stable. Moreover, an improved six-point finite-difference scheme with high accuracy independent of specific structures of waveguide is also constructed to approximate the cross-coupling terms along the transverse directions. The imaginary-distance procedure is used to assess the validity and utility of the present method. The field patterns and the normalized propagation constants of the fundamental mode for a buried rectangular waveguide and a rib waveguide are presented. Solutions are in excellent agreement with the benchmark results from the modal transverse resonance method.展开更多
We numerically investigate the regulation of beam direction by a single layer of high electrical permittivity nanorods with two kinds of cross-arranged radii. It is found that an oblique incident optical beam transmit...We numerically investigate the regulation of beam direction by a single layer of high electrical permittivity nanorods with two kinds of cross-arranged radii. It is found that an oblique incident optical beam transmits more than 95% with a wide range wavelength of 80 nm near 1550 nm in a negative direction. In particular the efficiency can be up to 100% around the wavelength of 1550nm at a wide-range angle. The results are very promising for designing subwavelength optical elements to realize beam steering in optical integrated circuits.展开更多
The photorefractive properties of lithium niobate crystals depend strongly on the kind of doping admixture. Study of LiNbO3 crystals with various doping admixtures using photorefractive light scattering allows insight...The photorefractive properties of lithium niobate crystals depend strongly on the kind of doping admixture. Study of LiNbO3 crystals with various doping admixtures using photorefractive light scattering allows insight into the processes taking place in the crystals. This paper presents new experimental results of non-selective and selective photorefractive light scattering investigations into rhodium-doped lithium niobate crystals and proposes a model to explain the experimental data.展开更多
A low loss photonic crystal （PhC） waveguide having rectangular air holes in Si core is proposed having an average group index of 55 in the bandwidth of 1.2 THz. The possible propagation losses due to inefficient cou...A low loss photonic crystal （PhC） waveguide having rectangular air holes in Si core is proposed having an average group index of 55 in the bandwidth of 1.2 THz. The possible propagation losses due to inefficient coupling arc also investigated for proposed structure. It is found that high transmission is obtained for a broad bandwidth from the output of the finally designed heterogeneous waveguide consisting of a slow liquid crystal infiltrated PhC waveguide surrounded by fast PhC waveguides on both sides.展开更多
A finite difference scheme based on the polynomial interpolation is constructed to solve the quasi-vector equations for optical waveguides with step-index profiles. The discontinuities of the normal components of the ...A finite difference scheme based on the polynomial interpolation is constructed to solve the quasi-vector equations for optical waveguides with step-index profiles. The discontinuities of the normal components of the electric field across abrupt dielectric interfaces are taken into account. The numerical results include the polarization effects, but the memory requirement is the same as in solving the scalar wave equation. Moreover, the proposed finite difference scheme can be applied to both uniform and non-uniform mesh grids. The modal propagation constants and field distributions for a buried rectangular waveguide and a rib waveguide are presented. Solutions are compared favorably with those obtained by the numerical approaches published earlier.展开更多
An all-optical header extraction scheme based on the reflective semiconductor optical amplifier (RSOA) is presented, which can be used to process variable-length and bit-rate transparent packets. Through selecting the...An all-optical header extraction scheme based on the reflective semiconductor optical amplifier (RSOA) is presented, which can be used to process variable-length and bit-rate transparent packets. Through selecting the appropriate carrierlifetime of the RSOA, the payload pulses obtain smaller gains than header pulses and are considered to be compressed. By using the reflective structure, the header pulses can acquire larger gains than the payload twice, and the contrast radio (CR) is improved. The simulation results show that the CRs can reach 22.8 dB and 18 dB for the packets with header pulses at the rates of 2.5 Gb/s and 10 Gb/s, respectively, and these values can be optimized through properly selecting the structure parameters, such as the small-signal gain and saturation energy.展开更多
The modulation instability （MI） induced by cross-phase modulation （XPM） in dispersion-decreasing fiber （DDF）, whose dispersion decreases along the direction of propagation, is solved and analyzed by the pertur- ...The modulation instability （MI） induced by cross-phase modulation （XPM） in dispersion-decreasing fiber （DDF）, whose dispersion decreases along the direction of propagation, is solved and analyzed by the pertur- bation method for the extended nonlinear SchrSdinger equation, considering the higher-order dispersion. The change of the gain spectra with incident power and dispersion decaying factor are also given respec- tively. Due to the fourth-order dispersion, XPM occurs at two gain spectral regions in both the normal and the anomalous dispersion regimes of DDF. The two gain spectral regions in the anomalous dispersion regime are larger than those in the normal dispersion ond region in the anomalous dispersion regime is near regime. Moreover, the gain spectrum of the sec- zero compared with that in the normal dispersion regime, indicating that XPM can be easily produced in the anomalous dispersion regime. The spectral width increases with the increase of the incident optical power and the dispersion decaying factor.展开更多
Transmission of 40Gbit/s NRZ signal was successfully demonstrated over 219km of installed SMF in KT's Daejeon area network. After transmission, the measured power penalty was 0.5dB for all the tributary channels.
A modified alternating direction implicit approach is proposed to discretize the three-dimensional full-vectorial beam propagation method （3D-FV-BPM） formulation along the longitudinal direction. The cross-coupling ...A modified alternating direction implicit approach is proposed to discretize the three-dimensional full-vectorial beam propagation method （3D-FV-BPM） formulation along the longitudinal direction. The cross-coupling terms （CCTs） are neglected at the first substep, and then double used at the second substep. The order of two substeps is reversed for each transverse electric field component so that the CCTs are always expressed in an implicit form, thus the calculation is efficient and stable. Based on the multinomial interpolation, a universal finite difference scheme with a high accuracy is developed to approximate the 3D-FV-BPM formulation along the transverse directions, in which the discontinuities of the normal components of the electric field across the abrupt dielectric interfaces are taken into account and can be applied to both uniform and non-uniform grids. The corresponding imaginary-distance procedure is first applied to a buried rectangular and a GaAs-based deeply-etched rib waveguide. The field patterns and the normalized propagation constants of the fundamental and the first order modes are presented and the hybrid nature of the full-vectorial guided-modes is demonstrated, which shows the validity and utility of the present approach. Then the modal characteristics of the deeply- and shallow-etched rib waveguides based on the InGaAsp/InGaAsP strained multiple quantum wells in InP substrate are investigated in detail. The results are necessary for modeling and the design of the planar lightwave circuits or photonic integrated circuits based on these waveguides.展开更多
We have developed a subminiature gain flattening filter with the 90% volume reduced package compared with conventional ones. The excellent thermal stabilities for the transmission characteristics of 0.0002dB/℃and 0.6...We have developed a subminiature gain flattening filter with the 90% volume reduced package compared with conventional ones. The excellent thermal stabilities for the transmission characteristics of 0.0002dB/℃and 0.67pm/℃, and the high power durability up to 1 W were confirmed.展开更多
文摘A modified alternating direction implicit algorithm is proposed to solve the full-vectorial finite-difference beam propagation method formulation based on H fields. The cross-coupling terms are neglected in the first sub-step, but evaluated and doubly used in the second sub-step. The order of two sub-steps is reversed for each transverse magnetic field component so that the cross-coupling terms are always expressed in implicit form, thus the calculation is very efficient and stable. Moreover, an improved six-point finite-difference scheme with high accuracy independent of specific structures of waveguide is also constructed to approximate the cross-coupling terms along the transverse directions. The imaginary-distance procedure is used to assess the validity and utility of the present method. The field patterns and the normalized propagation constants of the fundamental mode for a buried rectangular waveguide and a rib waveguide are presented. Solutions are in excellent agreement with the benchmark results from the modal transverse resonance method.
基金Supported by the National Natural Science Foundation of China under Grant No 11374041, the National Basic Research Program of China under Grant No 2010CB923202, and the Fund of State Key Laboratory of Information Photonics and Optical Communications of Beijing University of Posts and Telecommunications.
文摘We numerically investigate the regulation of beam direction by a single layer of high electrical permittivity nanorods with two kinds of cross-arranged radii. It is found that an oblique incident optical beam transmits more than 95% with a wide range wavelength of 80 nm near 1550 nm in a negative direction. In particular the efficiency can be up to 100% around the wavelength of 1550nm at a wide-range angle. The results are very promising for designing subwavelength optical elements to realize beam steering in optical integrated circuits.
文摘The photorefractive properties of lithium niobate crystals depend strongly on the kind of doping admixture. Study of LiNbO3 crystals with various doping admixtures using photorefractive light scattering allows insight into the processes taking place in the crystals. This paper presents new experimental results of non-selective and selective photorefractive light scattering investigations into rhodium-doped lithium niobate crystals and proposes a model to explain the experimental data.
基金supported by the TIFAC Centre of Relevance and Excellence in Fiber Optics and Optical Communication at the Delhi College of Engineering,Delhi" through the "Mission REACH" Program of Technology Vision-2020 of the Government of India
文摘A low loss photonic crystal （PhC） waveguide having rectangular air holes in Si core is proposed having an average group index of 55 in the bandwidth of 1.2 THz. The possible propagation losses due to inefficient coupling arc also investigated for proposed structure. It is found that high transmission is obtained for a broad bandwidth from the output of the finally designed heterogeneous waveguide consisting of a slow liquid crystal infiltrated PhC waveguide surrounded by fast PhC waveguides on both sides.
文摘A finite difference scheme based on the polynomial interpolation is constructed to solve the quasi-vector equations for optical waveguides with step-index profiles. The discontinuities of the normal components of the electric field across abrupt dielectric interfaces are taken into account. The numerical results include the polarization effects, but the memory requirement is the same as in solving the scalar wave equation. Moreover, the proposed finite difference scheme can be applied to both uniform and non-uniform mesh grids. The modal propagation constants and field distributions for a buried rectangular waveguide and a rib waveguide are presented. Solutions are compared favorably with those obtained by the numerical approaches published earlier.
基金supported by the National Natural Science Foundation of China (No.60972025)
文摘An all-optical header extraction scheme based on the reflective semiconductor optical amplifier (RSOA) is presented, which can be used to process variable-length and bit-rate transparent packets. Through selecting the appropriate carrierlifetime of the RSOA, the payload pulses obtain smaller gains than header pulses and are considered to be compressed. By using the reflective structure, the header pulses can acquire larger gains than the payload twice, and the contrast radio (CR) is improved. The simulation results show that the CRs can reach 22.8 dB and 18 dB for the packets with header pulses at the rates of 2.5 Gb/s and 10 Gb/s, respectively, and these values can be optimized through properly selecting the structure parameters, such as the small-signal gain and saturation energy.
基金supported by the National Natural Science Foundations of China under Grant Nos.60972025 and 61271206
文摘The modulation instability （MI） induced by cross-phase modulation （XPM） in dispersion-decreasing fiber （DDF）, whose dispersion decreases along the direction of propagation, is solved and analyzed by the pertur- bation method for the extended nonlinear SchrSdinger equation, considering the higher-order dispersion. The change of the gain spectra with incident power and dispersion decaying factor are also given respec- tively. Due to the fourth-order dispersion, XPM occurs at two gain spectral regions in both the normal and the anomalous dispersion regimes of DDF. The two gain spectral regions in the anomalous dispersion regime are larger than those in the normal dispersion ond region in the anomalous dispersion regime is near regime. Moreover, the gain spectrum of the sec- zero compared with that in the normal dispersion regime, indicating that XPM can be easily produced in the anomalous dispersion regime. The spectral width increases with the increase of the incident optical power and the dispersion decaying factor.
文摘Transmission of 40Gbit/s NRZ signal was successfully demonstrated over 219km of installed SMF in KT's Daejeon area network. After transmission, the measured power penalty was 0.5dB for all the tributary channels.
文摘A modified alternating direction implicit approach is proposed to discretize the three-dimensional full-vectorial beam propagation method （3D-FV-BPM） formulation along the longitudinal direction. The cross-coupling terms （CCTs） are neglected at the first substep, and then double used at the second substep. The order of two substeps is reversed for each transverse electric field component so that the CCTs are always expressed in an implicit form, thus the calculation is efficient and stable. Based on the multinomial interpolation, a universal finite difference scheme with a high accuracy is developed to approximate the 3D-FV-BPM formulation along the transverse directions, in which the discontinuities of the normal components of the electric field across the abrupt dielectric interfaces are taken into account and can be applied to both uniform and non-uniform grids. The corresponding imaginary-distance procedure is first applied to a buried rectangular and a GaAs-based deeply-etched rib waveguide. The field patterns and the normalized propagation constants of the fundamental and the first order modes are presented and the hybrid nature of the full-vectorial guided-modes is demonstrated, which shows the validity and utility of the present approach. Then the modal characteristics of the deeply- and shallow-etched rib waveguides based on the InGaAsp/InGaAsP strained multiple quantum wells in InP substrate are investigated in detail. The results are necessary for modeling and the design of the planar lightwave circuits or photonic integrated circuits based on these waveguides.
文摘We have developed a subminiature gain flattening filter with the 90% volume reduced package compared with conventional ones. The excellent thermal stabilities for the transmission characteristics of 0.0002dB/℃and 0.67pm/℃, and the high power durability up to 1 W were confirmed.
