Extreme narrow photonic passbands generated from defective two-segment-connected triangular waveguide networks

In this paper, we investigate the optical transmission properties of perfect and defective two-segment-connected tri- angular waveguide networks （2SCTWNs） and find that after introducing defects in networks, many groups of transparent extreme narrow photonic passbands （ENPPs） will be created in the middle of the transmission spectra, the number for each group and the group number of ENPPs can he adjusted by the matching ratios of waveguide length （MRWLs）, the number of defects, and the number of unit cells of 2SCTWNs. The influences of MRWL, number of defects, and number of unit cells on the number, width, and position of these ENPPs are researched and a series of quantitative rules and prop- erties are obtained. It may be useful for the designing of high-sensitive optical switches, wavelength division multiplexers, extreme-narrowband filters, and other correlative waveguide network devices.

Characteristics of photonic bands generated by quadrangular multiconnected networks

In this paper, by means of the network equation and generalized dimensionless Floquet-Bloch theorem, we study the influences of the number of connected waveguide segments （NCWS） between adjacent nodes and the matching ratio of waveguide length （MRWL） on the photonic bands generated by quadrangular multiconnected networks （QMNs）, and obtain a series of formulae. It is found that multicombining networks （MCNs） and repetitive combining networks （RCNs） are equivalent to each other and they can all be simplified into the simplest fundamental combining systems. It would be useful for adjusting the number, widths, and positions of photonic bands, and would possess potential applications for the designing of all-optical devices and photonic network devices.

Photonic band structures of quadrangular multiconnected networks

By means of the network equation and generalized dimensionless Floquet-Bloch theorem, this paper investigates the properties of the band number and width for quadrangular multiconnected networks （QMNs） with a different number of connected waveguide segments （NCWSs） and various matching ratio of waveguide length （MRWL）. It is found that all photonic bands are wide bands when the MRWL is integer. If the integer attribute of MRWL is broken, narrow bands will be created from the wide band near the centre of band structure. For two-segment-connected networks and three-segment-connected networks, it obtains a series of formulae of the band number and width. On the other hand, it proposes a so-called concept of two-segment-connected quantum subsystem and uses it to discuss the complexity of the band structures of QMNs. Based on these formulae, one can dominate the number, width and position of photonic bands within designed frequencies by adjusting the NCWS and MRWL. There would be potential applications for designing optical switches, optical narrow-band filters, dense wavelength-division-multiplexing devices and other correlative waveguide network devices.

产生于双金字塔光波导网络的巨大光子带隙和强光子衰减

设计了一种由一维光波导构成的一维双金字塔光波导网络,利用网络方程、无量纲布洛赫定理、以及广义本征函数方法研究了这种光波导网络的光子带隙和光子衰减性质。研究发现:这种包含高密度三角形基元回路的有趣光波导网络能够产生巨大的完全光子带隙和超强的光子衰减。当网络中任意两个相邻结点都由波导长度配比为2∶1的两条一维波导线连接时,网络产生的光子带隙的中心带隙率可达到154%;仅仅包含8个原胞的这种2∶1双连通光波导网络,其光子带隙的平均衰减深度可超过10-21(这相当于-210 d B)。这种有趣的光波导网络可用于设计和开发宽带隙和强局域的光子器件。