Equilibrium mode distribution

About: Equilibrium mode distribution is a research topic. Over the lifetime, 928 publications have been published within this topic receiving 14939 citations.

D8. Analysis of optical fiber by using SEIM with VM: Application to optical fiber directional coupler

Abstract: In this paper, we propose an efficient method to find the modal fields and the corresponding propagation constants for a single mode step index optical fiber. The simple effective index method (SEIM-x) and the variational method (VM) are mixed. The Gaussian optical field distribution as a trial function is used. Thereby the circular waveguide converts into two slab waveguides, the first slab has constant refractive index with x-dependent thickness and the second slab has constant thickness with variable core refractive index which is the effective refractive index of the first slab which is as a function of their thickness. The variational parameters of the two slab waveguides are the same to make the field distribution depends upon the radial distance. The application to fiber directional coupler is done by using the coupled mode theory. The numerical results show that our analytical solution presents a good agreement with the published data.

Fiber-optic interferometer and interfering method thereof

Abstract: A fiber-optic interferometer is provided. The interferometer includes a first dual-mode optical fiber for receiving a light input and exciting a first spatial mode and a second spatial mode, a first modal processor connected to the first dual-mode optical fiber for selecting the first spatial mode and the second spatial mode, a second dual-mode optical fiber connected to the first modal processor for propagating the first spatial mode and the second spatial mode and producing a phase shift (Δ φ) between the first spatial mode and the second spatial mode in response to an external perturbation effect, a second modal processor connected to the second dual-mode optical fiber for re-selecting the first spatial mode and the second spatial mode and producing a first light output interference pattern, and an analyzer having a polarization axis and connected to the second modal filter for adjusting the first light output interference pattern to produce a second light output interference pattern, so that the second light output interference pattern obtains an optimal contrast (C) through an adjustment of the polarization axis.

Refractive Index Insensitive Temperature Sensor Based on Cascading Single Mode Fiber with Few Mode Fiber

Abstract: A refractive index insensitive temperature sensor is proposed base on cascading single mode fiber with few mode fiber(FMF). During the sensor preparation, the splicing current is set to 100 mA, and a section of FMF is no core-offset splicing between two single-mode fibers. Therefore, it can motivate the transmission mode preferably and form optical fiber Mach-Zehnder interferometer. The mode phase difference in FMF will be changed according to the outside environment. It will cause interference fringe shift. The parameter to be measured can be achieved by detecting the amount shift of interference spectrum. The FMF can transmit four modes with LP01, LP11, LP21, LP02. The transmission spectrum is also analyzed, which shows that they have two modes of LP01 and LP11 in sensor with the length of 81.5 mm. In the refractive index and temperature sensing experiment, the cascading FMF sensor with the length of 81.5 mm is used. The results show that the transmission spectrum of sensor appears obvious blue shift as temperature is increasing, the temperature sensitivity can be up to -85.9 pm·℃-1 within the range of 27.6~93.8 ℃ with good linearity. The refractive index sensitivity is 3.697 34 nm·RIU-1 within the range of 1.347 1~1.443 9. There is no obvious shift phenomenon in the transmission spectrum with the feature of refractive index insensitive. Therefore, compared with the traditional cladding mode and multimode interferometric fiber-optic sensor, the proposed sensor based on FMF is easier to control and analyze transmission mode has the advantages of simple structure, easy process and high sensitivity. It can avoid cross-sensitivity between temperature and refractive index measurement. Thus, it can be used for temperature detection of power system, biomedicine, aerospace and other fields.

Effect of dispersion on bandwidth of single mode optical fiber

Abstract: Dependence of spectrum of transmitted signal and parameters of single mode optical fiber on its bandwidth is analyzed. Wide spectrum of signal reduces bandwidth in a large degree. Length of fiber also significantly reduces bandwidth of single mode fiber. Streszczenie. Przeprowadzono analize zalezności pasma światlowodu jednomodowego w zalezności od jego parametrow i widma sygnalu. Szerokie widmo sygnalu oraz dlugośc wlokna znacznie redukują pasmo światlowodu (Wplyw dyspersji na pasmo światlowodu jednodomowego).