What is Optical fibers: Definition and 19 Discussions

An optical fiber (or fibre in British English) is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data transfer rates) than electrical cables. Fibers are used instead of metal wires because signals travel along them with less loss; in addition, fibers are immune to electromagnetic interference, a problem from which metal wires suffer. Fibers are also used for illumination and imaging, and are often wrapped in bundles so they may be used to carry light into, or images out of confined spaces, as in the case of a fiberscope. Specially designed fibers are also used for a variety of other applications, some of them being fiber optic sensors and fiber lasers.Optical fibers typically include a core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by the phenomenon of total internal reflection which causes the fiber to act as a waveguide. Fibers that support many propagation paths or transverse modes are called multi-mode fibers, while those that support a single mode are called single-mode fibers (SMF). Multi-mode fibers generally have a wider core diameter and are used for short-distance communication links and for applications where high power must be transmitted. Single-mode fibers are used for most communication links longer than 1,000 meters (3,300 ft).Being able to join optical fibers with low loss is important in fiber optic communication. This is more complex than joining electrical wire or cable and involves careful cleaving of the fibers, precise alignment of the fiber cores, and the coupling of these aligned cores. For applications that demand a permanent connection a fusion splice is common. In this technique, an electric arc is used to melt the ends of the fibers together. Another common technique is a mechanical splice, where the ends of the fibers are held in contact by mechanical force. Temporary or semi-permanent connections are made by means of specialized optical fiber connectors.The field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics. The term was coined by Indian-American physicist Narinder Singh Kapany, who is widely acknowledged as the father of fiber optics.

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  1. E

    Rearranging the equation for the cutoff condition in optical fibers

    Hello! In Optical fibers, let ##k_1## and ##k_2## be respectively the propagation constants in core and cladding, ##\beta## the propagation costant of a mode along the direction ##z##, ##a## the radius of the fiber. Using the normalized quantities ##u=a \sqrt{k_1^2 − \beta^2}## and ##w=a...
  2. E

    Modeling/Analysis of optical fibers

    Hello PF, I need some guide points to help me formulate a project idea on the topic of optical fibers. Namely, the professor suggested I should look for topics on modeling of optical fibers, analysis of different optical fibers, characteristics etc. and to work in a simulator, or perform a...
  3. E

    TE and TM modes in optical fibers

    In a step-index optical fiber, considering Bessel functions of order ##\nu = 0## and no ##\phi## dependence, it is possible to obtain two separate sets of components, which generate respectively TE and TM modes. In the former case, only ##E_{\phi}##, ##H_r##, ##H_z## are involved; in the latter...
  4. I

    How to calculate attenuation for optical fiber bundle?

    Hi, If I understood it correctly, the coefficient of attenuation for a single optical fiber, is alpha = (10/L)*log(P(0)/P(L)). Assuming if I knew the properties of the optical fiber and the amount of optical fiber in the bundle, then the total attenuation for the bundle is approximately number...
  5. Lord Crc

    Observation of laser pulse propagation in optical fibers

    Just wanted to share this, mainly because I really liked the videos (found in the supplementary section at the end). Moderators, feel free to move it to a more appropriate place. Observation of laser pulse propagation in optical fibers with a SPAD camera Recording processes and events that...
  6. OrangeYogi

    Critical bending radius of optical fibres

    Hello, How do I calculate the critical bending radius of a single mode optical fibre? I'm using a polyimide coated fibre with coating diameter of 155μm. The wavelength is 1550nm. Let me know if you have any questions. Thank you
  7. E

    Cross Phase Modulation in Optical Fibers (Fiber Optics)

    Hello everyone. I have been practicing for my exam in fiber optics, and stumbled upon the following question: We have a transmission system with 3 channels, composed of a single mode fiber and a dispersion compensation fiber. Specifications are given for each. We need to calculate the channel's...
  8. L

    What is Nonlinear Fourier Transform in Optical Fiber Communication?

    Hi I am Ali, Liaquat. i am doing my PhD at University of Melbourne at Department of Electrical and electronics Engineering, my majors is optics and photonics. I am currently working in optical fiber communication.
  9. Daoyang

    Can I control the lighting of thousands of optical fibers?

    Hi everyone! This is my first post. I hope I am posting in the right place -- if not, please let me know. I am also hoping my question will not sound too absurd; I am no physicist, just someone who would like to use complex technology to create an art installation, and I'm having a hard time...
  10. Padrepapp

    Coupling Xe Arc Lamp into Fiber Bundle

    Hey, we are trying to couple the light of a 75 W Xe Arc Lamp (Hamamatsu L2194) into a 800um(0,8mm) diameter fiber bundle (7 fibers). Now we have 2 plano convex lenses (25mm diameter, 30mm EFL, edmund serial #45-364), the first for collimating the second for focusing onto the fiber. We are...
  11. F

    How to calculate mode overlap with I(x,y) rather than E(x,y)

    Hi I have a waveguide that is rectangular and multimode that I but-couple to a standard telecom SMF28 fiber. I have imaged the output of the waveguide and the fiber with a 25X microscope objective onto the chip of an IR-camera. Usually the mode overlap is calculated by cross-correlation of the...
  12. A

    Solving Vector Modal Equation

    I need help solving the vector modal equation for a step index fiber having a constant refractive index in the core and the cladding. (Under the conditions of zero dispersion and absorption.
  13. S

    Optical Fiber Link: 1500Km, 10Gbps NRZ

    Homework Statement [/B] Below is the original question and I just want to check out my answer of part one only. A single mode optical fiber link is required to link two major cities that are 1500 Km apart. The link must be capable of transmitting a minimum (NRZ) data rate of 10Gbps. The...
  14. U

    Single and multimode optical fibers

    Hi everyone, Sorry this is probably a really dull question but I'm intrigued nonetheless. I use a microscope that has multiple visible light lasers for excitation. The incident light is fed to the microscope through optical fibers. There is a single mode and a multimode fiber. I have been...
  15. A

    Experimenting the Speed of Light with Optical Fibers

    I did an experiment on the speed of light with different length of optical fibers. I know that the fiber has a refraction index of 1.49. I would like to know if I need to take in account the total internal reflection of the optical fibers too. Because when I use long fibers like for exemple...
  16. C

    Exploring Light Transmission with Lasers & Optical Fibers

    Why is it that we are able to use a laser beam with optical fiber but not with a white light source?
  17. D

    Understanding Phase Velocity in Optical Fibers

    Hi do u know what phase velocity is>? I have found it a boot for optical fibers vp=1/(srqt(em) m denotes greek m letter
  18. D

    Understanding Single Mode Fiber and Cladding Materials

    Hi i have some questions concerning optical fibers.. I want to know how the single mode fiber works.. I know that the light in sinle mode fiber travels across the middle of the fiber.. I can't understand why if we bend a little the fiber why the light don't hit the walls of the fiber? Thx a lot
  19. R

    Understanding Hydroxyl Diffusion in Optical Fibers: Causes and Effects"

    It seems that a major concern in the fabrication of optical fibers is hydroxyl diffusion into the fibers. I understand that a high hydroxyl concentration can lead to much higher attenuation. I don't know why though. Can someone please explain to me why the hydroxyl concentration affects...