Two-wavelength WDM multiplexers based on combined fiber structures

One of the main directions in the development of optical communication systems is associated with the use of optical fiber (ОF) for data reception and transmission. Therefore, manufacturers began to pay special attention to the creation of new brands of OF, improving their optical and operational characteristics. This makes it possible to improve existing optical fiber components that use OF as an active medium. The most widely used are two-wavelength 1 × 2 WDM multiplexers/demultiplexers designed to separate and combine optical carriers with wavelengths of 1310 and 1550 nm, corresponding to the second and third transparency windows of quartz OF. It should be noted that multiplexers and demultiplexers are the same optical devices, which are spectrally selective splitters. Such devices are distinguished by a sufficiently high level of optical characteristics at a relatively low cost of products. However, an analysis of the multiplexers produced in recent years shows that the characteristics of these devices do not sufficiently correspond to the set of modern requirements imposed by most system developers, in particular on permissible values of external influencing factors, insertion loss and the value of optical isolation of channels. Therefore, the development and research of WDM multiplexers with improved optical characteristics is relevant. One of the possible ways of optimizing such devices using new types of OF with resistance to bending losses, of which WDM multiplexers could be made. In this paper, we consider the possibilities of realizing fused single-mode multiplexers/demultiplexers based on combined fiber structures. The technology and equipment for the manufacture of these devices are presented. The optical characteristics of experimental samples of WDM multiplexers are investigated. The results of testing for the effect of temperature are given.

Reactive Power Compensation and Power Factor Correction by using Static VAR Compensator (SVC)

In this paper, a reactive power compensation system using static VAR compensator is presented. To confine on system stability and reliability, the reactive power compensation is the fundamental way forflexible AC transmission systems (FACTS). The variations of reactive power have an effect on thegenerating units, lines, circuit breakers, transformers, relays, and isolators. It can also cause effective voltage sags and increase losses. In the proposed system, the lead time between voltage pulse and curren pulse is measured and fed to the interrupt pins of the microcontroller where the program takes over to bring the shunt capacitors to the circuit to get the reactive power compensated. Back-to-back SCRs interfaced through optical isolation from the microcontroller are used in parallel for controlling the capacitor.

Nonlocality-Enabled Magnetic Free Optical Isolation in Hyperbolic Metamaterials

Hereby, we present an optical isolator (optical diode) based on a hyperbolic metamaterial (HMM). We demonstrate that a grating-free planar linear non-magnetic HMM structure deposited on a high-index substrate, which, due to presence of strong spatial dispersion (non-locality), reveals asymmetrical transmittance and reflectance characteristics for light of arbitrary polarization within a wide angular and spectral range. The presented device may be efficiently utilized to completely block backward and enforce unidirectional propagation in free space and integrated systems without the use of magnetooptical or non-linear effects.

Demonstration of an integrated nanophotonic chip-scale alkali vapor magnetometer using inverse design

Recently, there has been growing interest in the miniaturization and integration of atomic-based quantum technologies. In addition to the obvious advantages brought by such integration in facilitating mass production, reducing the footprint, and reducing the cost, the flexibility offered by on-chip integration enables the development of new concepts and capabilities. In particular, recent advanced techniques based on computer-assisted optimization algorithms enable the development of newly engineered photonic structures with unconventional functionalities. Taking this concept further, we hereby demonstrate the design, fabrication, and experimental characterization of an integrated nanophotonic-atomic chip magnetometer based on alkali vapor with a micrometer-scale spatial resolution and a magnetic sensitivity of 700 pT/√Hz. The presented platform paves the way for future applications using integrated photonic–atomic chips, including high-spatial-resolution magnetometry, near-field vectorial imaging, magnetically induced switching, and optical isolation.

Optical Isolation using Compact Time-modulated Cavity Array

It is shown using coupled mode theory and verified using finite-difference time-domain simulations how a time-modulated three-cavity array can be designed to allow transmission from port 1 to port 2 but to prevent transmission from port 2 to port 1 thereby implementing optical isolation. The reciprocity of the system is broken by phase-shifting the modulation signal applied to each cavity by 120 degrees which gives the system a synthetic linear momentum.