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Extraordinary transmission and reflection in ${PT}$-symmetric two-segment-connected triangular optical waveguide networks with perfect and broken integer waveguide length ratios
摘要： By adjusting the waveguide length ratio, we study the extraordinary characteristics of electromagnetic waves propagating in one-dimensional (1D) parity-time-symmetric (???? -symmetric) two-segment-connected triangular optical waveguide networks with perfect and broken integer waveguide length ratios respectively. It is found that the number and the corresponding frequencies of the extremum spontaneous ???? -symmetric breaking points are dependent on the waveguide length ratio. Near the extremum breaking points, ultrastrong extraordinary transmissions are created and the maximal can arrive at, respectively, 2.4079 × 1014 and 4.3555 × 1013 in both kinds of networks. However, bidirectional invisibility can only be produced by the networks with broken integer waveguide length ratio, whose mechanism is explained in detail from the perspective of photonic band structure. The findings of this work can be useful optical characteristic control in the fabrication of ???? -symmetric optical waveguide networks, which possesses great potential in designing optical amplifiers, optical energy saver devices, and special optical filters.
关键词： optical waveguide network,parity-time symmetry,integer broken ratios
更新于2025-09-19 17:13:59
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Theoretical Design of a Pump-Free Ultrahigh Efficiency All-Optical Switching Based on a Defect Ring Optical Waveguide Network
摘要： A theoretical design of a defect ring optical waveguide network is proposed to construct a pump-free ultrahigh efficiency all-optical switch. This switch creates ultrastrong photonic localization and causes the nonlinear dielectric in the defect waveguide to intensely respond. At its ON state, this material defect without Kerr response helps to produce a pair of sharp pass bands in the transmission spectrum to form the dual channel of the all-optical switch. When it is switched to its OFF state, the strong Kerr response induced refractive index change in the high nonlinear defect waveguide strongly alters the spectrum, leading to a collapse of the dual channels. Network equation and generalized eigenfunction method are used to numerically calculate the optical properties of the switch and obtain a threshold control energy of about 2.90 zJ, which is eight orders of magnitude lower than previously reported. The switching efficiency/transmission ratio exceeds 3×1011, which is six orders of magnitude larger than previously reported. The state transition time is nearly 108 fs, which is approximately two orders of magnitude faster than the previously reported shortest time. Furthermore, the switch size can be much smaller than 2.6 μm and will be suitable for integration.
关键词： ultrafast optics,pump-free,all-optical switching,ultrahigh efficiency,nonlinear optics,waveguide network
更新于2025-09-11 14:15:04