Fiber Optics Presentation

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					Jonathan Hartzler                         PHY 202/E                             Page 1 of 3
ID # 193855                             (718) 277-6567          

                                       Fiber Optics

        Fiber Optics (or optical fibers) are long, thin, flexible strands of extremely pure

glass, about the diameter of the human hair. These strands are arranged in bundles called

optical cables. These cables are used to transmit information, in the form of light signals,

over long distances. These cables look similar to any electrical cable you might see on

your computer.

How does an optical fiber work?

        Imagine a spotlight shining down a straight hallway. The beam of light travels

down the hallway, since the hall is straight there is no problem. What if there is a bend in

the hall? You could place a mirror at the corner to reflect the light. If the hallway has

multiple bends you would need multiple mirrors to cause the light to bounce back and

forth down the hall. That is exactly what happens with an optical fiber. A light signal is

sent out by a laser or an LED and is carried by the optical fiber to a receiver (see

illustration below).

Illustration Courtesy of

        The core of an optical fiber is the part that transmits the optical signal and the

cladding is a mirror lined wall that causes the signal to “bounce” its way through the

Jonathan Hartzler                        PHY 202/E                               Page 2 of 3
ID # 193855                            (718) 277-6567            

fiber(as in the illustration above)—a principle known as total internal refraction. Due to

signal loss over long distances something is needed to “boost” the signal, these

“boosters” are known as regenerators.

What are the advantages of Fiber Optics?

   Why are fiber-optic systems revolutionizing telecommunications? Compared to

conventional metal wire (copper wire), optical fibers are:

      Less expensive - Several miles of optical cable can be made cheaper than

       equivalent lengths of copper wire. This saves your provider (cable TV, Internet,

       phone) and you money.

      Thinner - Optical fibers can be drawn to smaller diameters than copper wire.

      Higher carrying capacity - Because optical fibers are thinner than copper wires,

       more fibers can be bundled into a given-diameter cable than copper wires. This

       allows more phone lines to go over the same cable or more channels to come

       through the cable into your cable TV box.

      Less signal degradation - The loss of signal in optical fiber is less than in copper


      Light signals - Unlike electrical signals in copper wires, light signals from one fiber

       do not interfere with those of other fibers in the same cable. This means clearer

       phone conversations or TV reception.

      Low power - Because signals in optical fibers degrade less, lower-power

       transmitters can be used instead of the high-voltage electrical transmitters needed

       for copper wires. Again, this saves your provider and you money.

      Non-flammable - Because no electricity is passed through optical fibers, there is no

       fire hazard.

Jonathan Hartzler                         PHY 202/E                              Page 3 of 3
ID # 193855                             (718) 277-6567           

       Flexible - Because fiber optics are so flexible and can transmit and receive light,

        they are used in many flexible digital cameras for the following purposes:

               Medical imaging - in bronchoscopes, endoscopes, laparoscopes

               Mechanical imaging - inspecting mechanical welds in pipes and engines

               Plumbing - to inspect sewer lines

        Because of these advantages, we see fiber optics in many industries, most notably

telecommunications and computer networks. For example, if you telephone Europe from the

United States (or vice versa) and the signal is bounced off a communications satellite, you

often hear an echo on the line. But with transatlantic fiber-optic cables, you have a direct

connection with no echoes.

        In conclusion, fiber optics are thin strands of flexible glass that transmit

information in the form of light signals across long distances. Fiber optics have many

advantages over copper wire and will likely become more and more common in the use

of telecommunications in the future.


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