Fiber Optic Attenuator

A study of a bending-type fiber-optic attenuator has been carried out. It is shown that the use of G.655 - optical fiber provides the largest dynamic range of the attenuator. The spectral dependence of the bending losses was measured in a wide range of wavelengths: from 1270 to 1610 nm.

To Optimize Fiber Lay Length in OPGW Cables Used in Power Transmission Networks

In this paper, the optimal fiber length in optical ground wire (OPGW) cable during production process is determined. The results show that in OPGW cable, if the fiber stranding length is less than the maximum lay length, the ultimate tensile stress (UTS) percentage decreases, but if it is higher, it would increase the bending losses and uses more fiber length, which is economically not viable. The calculation results show that by determining the maximum fiber lay length, the UTS percentage of OPGW cable can be controlled for a desired value.

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.

Design and Simulation of Ultra low loss Spiral Delay line for Integrated Optical Coherence Tomography

We report a design of 55 cm long spiral delay line at 850 nm wavelength. Propagation characteristics were simulated and analysed with fully vectorial Eigen Mode Expansion (EME) method. Bending losses were calculated and analysed for the optimization of minimum bending radius for reported structure. We have also simulated and analysed excess loss for a broadband of 200 nm at 850 nm operating wavelength. An excess loss of less than 0.2 dB is reported for the structure over the entire bandwidth range. The structure was further simulated for individual Transverse Electric (TE) and Transverse Magnetic (TM) modes and the analysis showed better results for TM mode. Reported structure is easy to fabricate, ultra-low loss and also broadband over 200 nm with a foot print of only 6×6 sq. mm. So, this design will improvise the reference arm section and will enhance the depth scanning of integrated optics based optical coherence tomography system.

Real-Time Humidity Measurement during Sports Activity using Optical Fibre Sensing

An optical fibre sensor for monitoring relative humidity (RH) changes during exercise is demonstrated. The humidity sensor comprises a tip coating of poly (allylamine hydrochloride) (PAH)/silica nanoparticles (SiO2 NPs) deposited using the layer-by-layer technique. An uncoated fibre is employed to compensate for bending losses that are likely to occur during movement. A linear fit to the response of the sensing system to RH demonstrates a sensitivity of 3.02 mV/% (R2 = 0.96), hysteresis ± 1.17% RH when 11 bilayers of PAH/SiO2 NPs are coated on the tip of the fibre. The performance of two different textiles (100% cotton and 100% polyester) were tested in real-time relative humidity measurement for 10 healthy volunteers. The results demonstrate the moisture wicking properties of polyester in that the relative humidity dropped more rapidly after cessation of exercise compared to cotton. The approach has the potential to be used to monitor sports performance and by clothing developers for characterising different garment designs.