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Basic Optical Waveguide Circuit
Published in Yasuo Kokubun, Lightwave Engineering, 2018
As mentioned in Section 5.1.4, light propagation in the optical waveguide can be accurately described by the superposition of eigenmodes of the waveguide. However, in the analysis of light propagation for the tapered waveguide or the branching and merging waveguides of which the structure changes along the propagation direction, there is a limit to the eigenmode expansion method, and approximations such as the local normal mode [2] are necessary. However, even if it can be described analytically, the equation is complicated, so the outlook for such approximations is poor and the advantage of using them is small. Thus, the beam propagation method (BPM) or the propagating beam method [49]–[54], in which the light guided in the optical waveguide is treated as a propagation of a beam wave, was developed. In addition, the finite difference time domain method [55] (FDTD) has also been used recently to analyze optical waveguides and optical devices, in which the sequential changes with time of the electric and the magnetic fields are followed by tracing exactly Maxwell’s equations and taking into consideration the boundary conditions at small intervals in space. However, this section will only describe a summary of BPM due to page volume constraints. Readers who want to learn more details may refer to [49] to [55].
Photonic Integrated Circuits
Published in Robert G. Hunsperger, Photonic Devices and Systems, 2017
New ways of implementing the beam propagation method have been and continue to be actively developed. Some of these improved versions overcome accuracy problems such as the approximation in Eq. (72) valid to second order and implement improved tapering of the computation window. Considerable effort has also been dedicated to developing new ways to handle accurately the broad Fourier spectra associated with step-index structures. Research has also been directed at improving computational efficiency and effectively combining the beam propagation method with other numerical techniques.
Phase discontinuities induced scintillation enhancement: coherent vortex beams propagating through weak oceanic turbulence
Published in Waves in Random and Complex Media, 2021
Hantao Wang, Huajun Zhang, Mingyuan Ren, Jinren Yao, Yu Zhang
In Section 3, the scintillation enhancement is presented in theory. To further verify this interesting phenomenon, in this section, we refer to the phase screen method in Ref. [36] to demonstrate the propagation process of the beam containing two types of phase discontinuities through weak oceanic turbulence. The schematic of the simulation of the beam propagation through oceanic turbulence using the numerical phase screen method is illustrated in Figure 6. The phase screens are arranged into a line with equal separation distances. Each phase screen represents the random phase fluctuation caused by a segment of the continuous medium. The original beam from the light source propagating through a series of phase screens is used to simulate the beam propagation through oceanic turbulence. And the results can be observed at the receiving plane. The parameters of the simulation are set to be the same as that in Figure 3(a) for convenient comparison, and the propagation distance is set to be . For the setup of the simulation, five phase screens with the size of are placed at intervals along the propagation path. Each phase screen has points of analysis. And the split-step beam propagation method is used to simulate the propagation.
Novel polymer waveguide-based surface plasmon resonance (SPR) sensor
Published in Instrumentation Science & Technology, 2020
Yiying Gu, Jiahui Yang, Jiayi Zhao, Yang Zhang, Shuangyue Yang, Jingjing Hu, Mingshan Zhao
The BeamPROP software was used to simulate the mode field distribution in the waveguide and fiber, respectively, based on the beam propagation method. The mode field of the waveguide core layer and the minimum mode field of conical lens fiber, respectively, are shown in Figure 13(a) and 13(b). The maximum coupling efficiency between the tapered fiber and the waveguide was approximately 80%.