why optical fiber has large bandwidh?

[suvendu]

dear sir,
please tell me what r the reason that the optical fiber has large bandwidh?

 

[IanP]

Cutting story short, optical (light) waves as a carrier wave provides an enormous potential bandwidth. Optical carriers are in the region of 10 to the power of 13 Hz to 10 to the power of 16 Hz, and that is for example three to six orders of magnitude higher than microwave frequencies.
But don't be tricked by this high carrier frequency. Check this explenation on real bandwidth in optical fibre: **broken link removed**
Regards,
IanP

 

[comsians]

it is because of the two main reasons

Firstly
it has many optical light paths known as "Europian 1" or called "E1"

Each E1 has a capacity of 2MB for data sending


2ndly because the power losses of data or signal is less than compare to other mediums

 

[Belsugului]

Hi

comsians wrote:

it has many optical light paths known as "Europian 1" or called "E1"

That has nothing to do with the large badwidth.

the same is true for the second one:

the power losses of data or signal is less than compare to other mediums

The first one is a hystorical thing, the first digital transmission was through E1 (T1 ine USA) where 32 time sharing channels (one channel for each voice) was used to be carried on the same medium (coax cable). In order to note through away the old stuff newer staff was made compatible with E1. Thus STM1 can transport 63 E1s.
The 2nd one is an additional advantage, that you do not need to have repeaters at every couple of kms in case of coax cable or 5-10 kms in case of microwave, but only 10-20 km at multimode fiber and 60-80 km in case of single mode fiber.

The answer to your question was given correctly by IanP

Belsugului

 

[rfmw]

Anyone knows the maximal usable (theoretical) bandwidth of a single-mode optical fiber using all the "windows"? Is in not 50 THz?

 

[electron_boy]

optical fibers have a large bandwidth bcoz the light b/w is nealy 10^13 -10^15 hz

 

[power-twq]

because fiber's loss is very low.

best regards

dear sir,
please tell me what r the reason that the optical fiber has large bandwidh?

 

[userdce]

fiber's loss has nothng to do with bandwidth

unless only for particular frequency that loss is there

 

[Lachezar]

In Fiber optics ,the more important thing is "BITRATE PRODUCT" not the bit rate itself,meaning maximum bit rate times distance(BL).
The bandwith (GB/S)depends on many factors such as modal dispersion D,material dispersion (b2 and b3) ,wavelength, what kind of source you have
lazer or Led,gaussian pulse phase chirp ,nonlinear effects so on. To answer the question,you have to go through serios statistic equations and Fourier transforms(unless you have very simple case b3=0,chirp=0,single mode,Gaussian pulse).It is impossible to answer the questions without using heavy math accounting for all those thinks i said before.
"Fiber optics communication systems" by Govind Agrawal chapter3 explains it in detail


LT

 

[El-Hadidy]

hello,

I suppose this occurs due to the fact that light has different characteristics than normal voltage or current.

Thanks

El-Hadidy

 

[sabari]

so many critical angles hence large bandwidth

 

[jjohn]

* Gambling, W. A., "The Rise and Rise of Optical Fibers", IEEE Journal on Selected Topics in Quantum Electronics, Vol. 6, No. 6, pp. 1084-1093, Nov./Dec. 2000
* Gowar, John, Optical Communication Systems, 2 ed., Prentice-Hall, Hempstead UK, 1993 (ISBN 0136387276)
* Hecht, Jeff, City of Light, The Story of Fiber Optics, Oxford University Press, New York, 1999 (ISBN 0195108183)
* Hecht, Jeff, Understanding Fiber Optics, 4th ed., Prentice-Hall, Upper Saddle River, NJ, USA 2002 (ISBN 0130278289)
* Nagel S. R., MacChesney J. B., Walker K. L., "An Overview of the Modified Chemical Vapor Deposition (MCVD) Process and Performance", IEEE Journal of Quantum Mechanics, Vol. QE-18, No. 4, April 1982
* Ramaswami, R., Sivarajan, K. N., Optical Networks: A Practical Perspective, Morgan Kaufmann Publishers, San Francisco, 1998 (ISBN 1558604456)


May be tried..

 

[kkeiser]

It is the properties of fibre (transporting media) provides the better bandwith.

 

[tania_04]

the idea behind using optical fibre was due to the fact that the bandwidth is large due to the high frequency of light waves and ofcourse the very low loss of the line

 

[fatma1000]

i need a good material in optical netwarks please any one has any thig (books, software ....) please send it to me
regards

 

[dkk]

i need a good material in optical netwarks please any one has any thig (books, software ....) please send it to me
regards

-----------------------------------------------------------------------------------------------In addition to last book listed by JJohn above
few more books are available

1. Optical Communication Networks by Biswanath Mukherjee -1997
Publisher - McGraw Hill
(Perhaps another edition is published in 2000 by Kluwer)

2. WDM Optical networks:Concepts Design and Networks By C.RamaMurthy and Mohan Guruswami
PublisherHI - 2002
ISBN-81-203-2129-4

3.Optical WDM networks:Concepts and design Principles by Jun Zheng and Hussein T. Mouftah
Publisher John Wiley and Sons and IEEE Press

You can find out on this board if the link for these books available else partly you can also see on google book search
DKK

Added after 13 minutes:

(A)Is the complete theoretical bandwidth is usable bandwidth in case of optical fiber? If not what are the hurdles?

(B) Supposing the total banbdwidth avaible theoretically is practically usable what will be scenario interms of data rate, no of channels or that signals that we can transmit at a given time?

 

[mizel]

Also, remember there are real world constraints. In the real world frequencies that are close to eachother cannot be used in fiber and we are limited by the rate at which actual electronics can sample the data (we can't sample at the speed of light).

This may not be relevant in the theoretical bandwidth of fiber, but they are interesting points if you ever consider real world applications.

 

[dkk]

i need a good material in optical netwarks please any one has any thig (books, software ....) please send it to me
regards

In addition to the the books listed above, for indepth inside into OPTICAL NETWORKs one can go through following text

1. EMERGING OPTICAL NETWORK TECHNOLOGIES :Architectures, Protocols
and Performance
Edited by
KRISHNA M. SIVALINGAM
University of Maryland, Baltimore County
SURESH SUBRAMANIAM
George Washington University


2. Metropolitan Area WDM Networks: An AWG-Based Approach
Martin Maier
ISBN 1-4020-7574-X, 2003
**broken link removed**

3. Optical Networks: Architecture and Survivability
Hussein T. Mouftah and Pin-Han Ho
ISBN 1-4020-7196-5, 2002
**broken link removed**

4. WDM Mesh Networks: Management and Survivability
Hui Zang
ISBN 1-4020-7355-0, 2002
**broken link removed**
DKK

 

[hshalaby]

bandwidth is rouphly 1/10 of the carrier frequency.
Since the optical carrier frequency is in the range of 10^14 Hz, its bandwidth is high.

 

[subharpe]

It is beacuse of purely the properties of Silicon di Oxide or glass. If you find the attenuation constant α, the attenuation per unit length vs. wavelength of light plots for Sio2, you will find there are two local minima around at 1.3 and 1.55 µm and the 3db points about these two minima which add up to nearly 120THz in frequency. This gives the enormous bandwidth for optical fiber.

Also the actual attenuation is a function of the length of the fiber. Like normal amplifiers where gain bandwidth product is a figure of merit for the amplifier, for optical fibers the legth bandwidth product is a figure of merit.