Evgenij LegotskojJune 28, 2015, 9:22 a.m.

FOTL - Tutorial 002.The optical fiber and its types

Depending on the number of the operating frequency propagating waves (modes) of the fibers and is separated into one multimode. The number of modes is dependent on the ratio of the diameter of the fiber core and the wavelength for optical fibers having step-index is calculated as follows.

α – fiber core radius,
λ – wavelength,
Δ – relative refractive index difference.

Since n 1 and n 2 have very similar meanings, the nominal value ∆ for most optical fibers is within

The advantage of single-mode optical fibers is the low dispersion (signal distortion), a large information-carrying capacity and range. Single-mode systems are the most actively developing and still promising direction of development of information transmission technology.

In multimode fibers pulse on the reception is broadened and distorted, which significantly limits the transmitted frequency band and the transmission distance. Multimode fibers are not used to transmit information over long distances. Generally transceivers operating on multimode fiber limited range of up to 500 meters.

For the characteristics of the optical fiber is essential in the refractive index profile in cross section. If the core of the fiber has a constant value over the radius of the refractive index, such optical fibers are called fiber optics with step refractive index profile (there is a step in the refractive index at the interface between the core and shell).

Also to fight with the broadening of pulses (that is especially true for multimode fibers) developed another type of fiber, which is found much more widely used in long-distance communications - is the optical fiber having a gradient refractive index profile. In optical fibers with a graded refractive index from the refractive index of the core center to the edge changes smoothly.

The refractive index is described by the following formula for the gradient optical fibers

r – the current range,
n 1 – the greatest value of the refractive index of the core,
g – coefficient determining the type of refractive index profile

Single-mode optical fibers can be divided into the following categories:

  • conventional or fiber unbiased variance (SF), which are issued for equipment operating at a wavelength of 1.31 microns;
  • dispersion-shifted fiber (DSF), which are available for use at a wavelength of 1.55 microns;
  • fibers with non-zero dispersion-shifted (NZDSF), for transmitting a multiplex signal in the working wave range of 1,53-1,56 mm

It is also distinguished from the aligned optical fiber cladding whose refractive index corresponds to the refractive index of optical fibers and with a stepped profile matched to the refractive index of pure quartz (n = 1,4585), and the depressed cladding material which consists of two zones.

The profiles of optical fibers with refractive indices unbiased variance:
а – aligned with the shell, б – a depressed shell

The single-mode optical fibers for dispersion-shifted complex refractive index profiles determining the core diameter is substantial difficulties, so these fibers introduce the concept of the mode field diameter. fashion subfield refers to the area of the light signal passing through the cross-section of the optical fiber. This field has a minimal optical signal attenuation and optical fiber extends along minimal power losses.

ω 0 – mode field radius
0 – mode field diameter

We recommend hosting TIMEWEB
We recommend hosting TIMEWEB
Stable hosting, on which the social network EVILEG is located. For projects on Django we recommend VDS hosting.
Support the author Donate


Only authorized users can post comments.
Please, Log in or Sign up

Let me recommend you the excellent hosting on which EVILEG is located.

For many years, Timeweb has been proving his stability.

For projects on Django I recommend VDS hosting

View Hosting

C++ - Тест 003. Условия и циклы

  • Result:7points,
  • Rating points-10
  • G1ROG
  • Feb. 27, 2021, 9:30 a.m.

C++ - Тест 003. Условия и циклы

  • Result:28points,
  • Rating points-10

C++ - Тест 003. Условия и циклы

  • Result:0points,
  • Rating points-10
Last comments

Django - Tutorial 001. Deploying a site on Django + PostgreSQL + Gunicorn + Nginx

А почему нельзя? Где можно об этом почитать? Киньте, пожалуйста, в меня ссылкой.

Django - Tutoral 049. Optimizing Django Performance with a Real Project

Огромное спасибо вам за статью! Для меня стали открытием select_related и prefetch_related
  • t1m4
  • Feb. 24, 2021, 2:56 a.m.

Django - Tutorial 052. Redefining a User Model

В данном случае я заходил под superuser но все равно не появлялись эти поля

Django - Tutorial 001. Deploying a site on Django + PostgreSQL + Gunicorn + Nginx

Поднял сервис с помощью systemd, вот по этому мануалу: https://habr.com/ru/post/501414/
  • t1m4
  • Feb. 23, 2021, 7:11 a.m.

Django - Tutorial 052. Redefining a User Model

А как дать ему эти права?
Now discuss on the forum

как добавить списки в список, которые созданы динамически

import numpy as np from pprint import pprint import collections from itertools import chain import pandas as pd from itertools import islice import time from i…

Не отдаётся статика на виртуальной машине

В итоге выставил 775 на все файлы проекта и всё заработало. Но я не уверен, что так правильно.
  • Pisych
  • March 3, 2021, 1:06 a.m.

Вывод данных из связанных таблиц.

Не знаю, правильно ли... Но работает <body>{% for i in CatList %} <ul> <li><h3>{{i.title}}</h3></li>{% for j in ProdList %}<ul>{…

нужна помощь с проектом qt c++

дали задание, на несколько дней. собираюсь делать, но хотел бы получить помощь более опытных людей, чтобы подкорректировать себя и подстраховаться. каким образом это можно сделать? …

QScrollArea dynamically add QCheckBoxes

Всё правильно. Это просто спамер, который отправился в вечный бан.
© EVILEG 2015-2020
Recommend hosting TIMEWEB