Fiber Optic Blog

what are differences of bare fiber,loose tube and tight buffer tube

Bare fiber

From the fiber production process, which the composition of the fiber from the inside out: the core, cladding, a coating, and secondary coating. Optical signals in optical fibers are using light of the principle of total reflection. The glass fiber is the main channel of transmission of optical signals, the cladding is used to reflect the optical signal, and the coating is to protect the fragile core. Bare fiber means it has not been coated fiber.

Loose tube

The loose tube is outside layer of protection for fiber. Because of fiber’s very fragile, easily broken, which the production will be one or more optical fibers placed inside the loose tube, and then fill in the ointment. Then, coupled with strengthening the core which used to increase the fiber optic cable strength and the outer sheath, such as aluminum foil and polyethylene jacket, became a fiber optic cable.

Tight buffer tube

With tight buffered single mode or multimode optical fiber secondary coating structure is called tight buffered optical fiber. The second set directly on the bare optical fiber is made of a coated optical fiber plastic, such as PVC, PVDF, LSZH, etc. It is the basic components for the manufacture of a variety of indoor cable, which can also be used alone. The tight buffer fiber can be used directly in pigtail for the connection of various types of optical active or passive components, instruments and terminal equipment connections.

Advantages of Using Patch cord

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Patch cord is an electrical or optical cable, which is used to connect one electronic or optical device to another for signal routing. Patch cords are the most niversal form of Ethernet cable available today. Patch cords are also used to route signals to mixing boards, processors, conditioners, drum machines and other instruments and components.

The features that separate one type of electrical patch cord from another are thickness, safeguarding, length and connectors. Patch cords are most commonly found in computer network rooms. They are used to connect patch panels to network devices. This provides connection to the computers which are blocked in the remote network jacks. The patch cord provide a choice to select between single and multiple modes. With a multi-mode fiber patch in deployment, one need not to worry about the speed, bandwidth and transfer direction of data. With a fundamentally high speed and high accuracy system in place, fiber optic patch cords supply you a low attenuation connection between the fiber network cables or from the cable to the device. These cables are able to carry more than one signal over its length at the same time, in a way that no two signals conflict with each other.

This helps significantly in improving the bandwidth and data transfer rate of the cables. The material used to make these cables is glass and plastic. They are never made of metal. These materials are neither ferromagnetic and nor paramagnetic. While patch and crossover cables may look the same, they are used for two distinctive situations. A crossover cable is reqiured when connecting networks or computers together directly. However, if you are connecting computers to a switch, hub or router a patch cord is what you’ll need.

How Fiber-Optic Internet Works

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You’ve probably heard of fiber-optic Internet. You might even know that it delivers incredibly fast Internet to more than 10 million homes using a fiber-to-the-home connection (FTTH). But do you know what makes fiber Internet different?

The secret? Fiber-optic technology. Fiber-optic Internet uses different equipment and technology than other providers, making it faster and more reliable.

So – how does fiber-optic Internet work?

Optical cables

Traditional cable Internet services use underground networks of copper coaxial cables to transmit data to subscriber homes.

But fiber-optic Internet uses optical cables. . These cables are made up of thousands of optical fibers containing three parts:

The core: The center of the cable; the part that light travels through.

The cladding: Reflective optical material that surrounds the core.

The buffer coating: A plastic barrier that protects the optical cable.

Comparison of Different Types of Optical Amplifiers

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Optical amplifier is an important technology for optical communication networks. Without the need to first convert it to an electrical signal, the optical amplifiers are now used instead of repeaters. As we know, there are several types of optical amplifiers. Among them, the main amplifier technologies are Doped fiber amplifier (eg. EDFA), Semiconductor optical amplifier (SOA) and Fiber Raman amplifier. Today, we are going to study and compare different types of optical amplifiers in this paper.

Before the comparison of the different types of optical amplifiers, let’s take a closer look at fiber optic amplifier. In general, a repeater includes a receiver and transmitter combined in one package. The receiver converts the incoming optical energy into electrical energy. The electrical output of the receiver drives the electrical input of the transmitter. The optical output of the transmitter represents an amplified version of the optical input signal plus noise. Repeaters do not work for fiber-optic networks, where many transmitters send signals to many receivers at different bit rates and in different formats. However, unlike a repeater, an optical amplifier amplify optical signal directly without electric and electric optical transformation. In addition, an ideal optical amplifier could support multi-channel operation over as wide as possible a wavelength band, provide flat gain over a large dynamic gain range, have a high saturated output power, low noise, and effective transient suppression. Several benefits of optical amplifiers as the following:

Support any bit rate and signal format

Support the entire region of wavelengths

Increase the capacity of fiber-optic links by using WDM

Provide the capability of all-optical networks, not just point-to-point links

OK, after a brief introduction of the optical amplifiers, we formally begin today’s main topic. As we talk above, there are three main types of today’s amplifier technology. Each of them has their own working principle, features and applications. We will describe them one by one in the following paragraphs.

Doped fiber amplifier (The typical representative: EDFA)

Erbium-doped fiber amplifier (EDFA) is the most widely used fiber-optic amplifiers, mainly made of Erbium-doped fiber (EDF), pump light source, optical couplers, optical isolators, optical filters and other components. Among them, a trace impurity in the form of a trivalent erbium ion is inserted into the optical fiber’s silica core to alter its optical properties and permit signal amplification.

Working Principle

The working principle of the EDFA is to use the pump light sources, which most often has a wavelength around 980 nm and sometimes around 1450 nm, excites the erbium ions (Er3+) into the 4I13/2 state (in the case of 980-nm pumping via 4I11/2), from where they can amplify light in the 1.5-μm wavelength region via stimulated emission back to the ground-state manifold 4I15/2.

Advantages & Disadvantages of EDFA

Advantages

EDFA has high pump power utilization (>50%)

Directly and simultaneously amplify a wide wavelength band (>80nm) in the 1550nm region, with a relatively flat gain

Flatness can be improved by gain-flattening optical filters

Gain in excess of 50 dB

Low noise figure suitable for long haul applications

Disadvantages

Size of EDFA is not small

It can not be integrated with other semiconductor deviecs

Semiconductor optical amplifier (SOA)

Semiconductor optical amplifier is one type of optical amplifier which use a semiconductor to provide the gain medium. They have a similar structure to Fabry–Perot laser diodes but with anti-reflection design elements at the end faces. Unlike other optical amplifiers SOAs are pumped electronically (i.e. directly via an applied current), and a separate pump laser is not required.

Technology Of Fiber Optic Amplifiers

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In fiber optic communication, the visible-light or infrared (IR) beams carried by a fiber are attenuated as they travel through the material. Then there comes to the fiber optic amplifier which is used to compensate for the wakening of information during the transmission.

Amplifiers are inserted at specific places to boost optical signals in a system where the signals are weak. This boost allows the signals to be successfully transmitted through the remaining cable length. In large networks, a long series of optical fiber amplifiers are placed in a sequence along the entire network link.

Common fiber optical amplifiers include Erbium-Doped Fiber Amplifier (or EDFA Optical Amplifier), Raman fiber amplifier, and silicon optical amplifier (SOA). Erbium doped fiber amplifier is the major type of the fiber amplifier used to boost the signal in the WDM fiber optic system, as we know it is WDM that increase the capacity of the fiber communications system and it is the erbium-doped fiber amplifier that makes WDM transmission possible. Fiber amplifiers are developed to support Dense Wavelength Division Multiplexing (DWDM) which is called DWDM EDFA amplifier and to expand to the other wavelength bands supported by fiber optics.

There are several different physical mechanisms that can be used to amplify a light signal, which correspond to the major types of optical amplifiers. In doped fibre amplifiers and bulk lasers, stimulated emission in the amplifier’s gain medium causes amplification of incoming light. In semiconductor optical amplifiers (SOAs), electron-hole recombination occurs. In Raman amplifiers, Raman scattering of incoming light with phonons in the lattice of the gain medium produces photons coherent with the incoming photons. Parametric amplifiers use parametric amplification.

When light is transmitted through matter, part of the light is scattered in random directions. A small part of the scattered light has frequencies removed from the frequency of the incident beam by quantities equal to the vibration frequencies of the material scattering system. Raman fiber optic amplifiers function within this small scattering range. If the initial beam is sufficiently intense and monochromatic, a threshold can be reached beyond which light at the Raman frequencies is amplified, builds up strongly, and generally exhibits the characteristics of stimulated emission. This is called the stimulated or coherent Raman effect.

EFDA fiber optic amplifier functions by adding erbium, rare earth ions, to the fiber core material as a dopant; typically in levels of a few hundred parts per million. The fiber is highly transparent at the erbium lasing wavelength of two to nine microns. When pumped by a laser diode, optical gain is created, and amplification occurs.

Silicon or semiconductor optical amplifier functions in a similar way to a basic laser. The structure is much the same, with two specially designed slabs of semiconductor material on top of each other, with another material in between them forming the “active layer”. An electrical current is set running through the device in order to excite electrons which can then fall back to the non-excited ground state and give out photons. Incoming optical signal stimulates emission of light at its own wavelength.

Fiber optic repeater also can re-amplify an attenuated signal but it can only function on a specific wavelength and is not suitable for WDM systems. That is the reason why fiber optic amplifier plays a much more important role in communication systems.

DWDM System Amplifiers

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DWDM EDFA is key component in DWDM network. It uses an optical supervisory channel power adjustment and extends the power link budget for long distance DWDM communication systems.

There are three main types of optical amplifiers: fiber amplifiers (EDFAS), semiconductor optical amplifiers(SOAs), and Raman amplifiers. Fiber amplifiers use rare earth elements usually erbium, but also oraseodymium, tellurite, neodymium, and others as dopant that are pumped with a laser of either 980 to 1480nm. The most commom used for WDM network are the EDFAs.

Types of EDFAs used for DWDM

1 Erbium-doped fiber amplifiers-EDFA. They are low nosie figure approximately 5dB and wide amplitication bandwidth. The EDFA is pumped at 980nm 0r 1480 nm.

2 Erbium-doped fluoride fiber amplifiers(EDFFA) provide for flatter gain spectrum without any gain flattening that introduces loss. They can absorb more erbium than silica producing flatter

band across the erbium passband, allowing the 1530 nm to 1542 region to be used for DWDM. SNR remains the same, or nearly the same for each channel. Howerver, fluoride EDFAs have higher noise from being pumped at 1480nm. DWDM channels must have flat gain through means of an amplifier to properly function. They have proved durable with wavelength stability better than 0.02nm per year.

In DWDM systems amplifiers are an enabling component. For 32 channel DWDM systems optical amplifiers will need to provide at least 25nm of usable bandwidth. 80Gbt/s with 10 Gbt/s channels need 8 wavelengths; 2.5 Gbt/s channels need 32 wavelengths. These must have high outout power and low noise and high signal to noise ratio(SNR). Network spans now at 360km are expected to extend to 600 km then to 2000 km with use of EDFAs. With optical amplifiers the optical signal does not have to be converted and is amplified optically in passing through the amplifier. Optcial fiber amplifiers generate stronger signals than regenerators and transmission can be for extended distances. This takes the place of the SONET regenerator.

There are three types if optical amplifiers used in DWDM system. These are:

1 Post amplifier are placed immediately after transmitter to increase optical power to the receiver.

2 In-line amplifiers boost the power level after transmission through a length of fiber permitting the signal to pass through another fiber segment. They are used to compensate for signal attenuation in long segments of fiber.

3 Pre-amplifiers boost the power of a signal just prior to the receiver.

FiberStore can provide DWDM EDFA amplifiers in different channel from 40~80 channels. These amplifiers offer high optical gain, low noise figure and high saturation optical power which are fully integrated with various kinds of DWDM system.

The optical circuit is designed especially for digital optical fiber communication system including

(1) lower noise figure;

(2)high output booster and high sensitivity Pre-Amplifier improve the system loss budget;

(3)Broad input power range and output power adjustable make it use easily.

The design of dual Power Mixed and hot swap make it has longer MTBF. Also, the power system can be backup.Employ the intelligent temperature control system,the fan is on when the module temperature over 45℃, meanwhile it will stop as the temperature is under 40℃, which makes sure the thermal stability and fan’s long life-time, meanwhile, the professional air flow design can also ensure the best temperature stability.Intelligent network management system. Perfectly network interface: Ethernet, RS-485 and RS-232 network interface,and the open mib ensure the connectivity with all other network management system.

Applications

Pre-Amplifier Online Amplifier

Booster

DWDM Optical System

Features

1.Low Noise Figure:Typical 4.5dB High Flatness: Typical 1dB

2.Cover Whole C-Band: Carrie 40 or 80 chs

3.Redundancy hot swap power module: 110/220VAC and 48VDC can plug Mix

4.Perfect Network Interface:Ethernet, RS-485 and RS-232 port

5.Support Telnet and SNMP network management

6.Gain can be adjustable by network and manual

7.High Precise AGC and ATC Circuit

8.High saturation output power

9.Flexible Mechanics and Circuit structure (Module, 1U rack and Gain Block)

10.OEM is available Compatible with Telecordia GR-1312-CORE

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