Basics on Fiber optics

1. Basics on Fiber optics • Wavelength http://en.wikipedia.org/wiki/Wavelength • Visible – The visible light that we see is just above Infrared. Recall how white light shown through a prism is broken down into the colors of a rainbow. This concept will be used in expanding the bandwidth of a single fiber optic cable. • Different colors have different wavelengths • Infrared: http://en.wikipedia.org/wiki/Infrared

2. Review - Engineering Notation – Numbers ≥1 AbbreviationUnits PrefixMultiplier Power of 10 T Tera- x 1,000,000,000,000 x 1012 G Giga- x 1,000,000,000 x 109 M Mega- x 1,000,000 x 106 K Kilo- x 1,000 x 103 Engineers only use powers of ten that are multiples of 3.

3. Scientific Notation – Numbers ≥1 Multiplier Power of Ten 1,000,000,000 = 1 x 109 100,000,000 = 1 x 108 10,000,000 = 1 x 107 1,000,000 = 1 x 106 100,000 = 1 x 105 10,000 = 1 x 104 1,000 = 1 x 103 100 = 1 x 102 10 = 1 x 101 1 = 1 x 100

4. Engineering Notation – Numbers <1 Abbrev.Units PrefixMultiplier Power of 10 m milli- µ micro- n nano- p pico- = x 10-3 = x 10-6 = x 10-9 = x 10-12 Engineers only use powers of ten that are multiples of 3.

5. Basic frequency breakdown • Radio waves up to 1GHz • Microwaves up to 150 THz • Light up to 1500 THz • X-Ray up to 500,000 THz • Gamma rays above that

6. Wavelengths • A wavelength is the distance between repeating units of a propagating wave of a given Frequency. It is commonly designated by the Greek letter lambda (λ). Examples of wave-like phenomena are light, water, waves in the ocean, and sound waves. • The wavelength is related to the frequency by the formula: wavelength = wave speed / frequency. • Wavelength is therefore inversely proportional to frequency. • Waves with higher frequencies have shorter wavelengths. Lower frequencies have longer wavelengths, assuming the speed of the wave is the same.

7. Wave lengths as it relates to distance

8. Infrared, note where Radar, TV and Radio fall in the spectrum

9. Types of fiber cable • Multimode –850 nm & 1300 (nano-meters) • Single mode 1330 nm 1550 nm • Basic components of a Fiber strand for either a multimode or single mode fiber • Buffer/coating • Cladding • Core • Multimode • Wavelength:s(λ)[850 nm]Frequency: (352.94118)[GHz] • 1300 nm 230.76923 [GHz] • Singlemode • 1310 nm 229.00763 [GHz] • 1550 nm 193.54839 [GHz]

10. Nano meters Abbrev.Units PrefixMultiplier Power of 10 m milli- µ micro- n nano- p pico- = x 10-3 = x 10-6 = x 10-9 = x 10-12 Engineers only use powers of ten that are multiples of 3.

11. Light path within a multimode fiberNote the different paths for light to take. This is where the term multi mode comes from-multiple paths or modes

13. Types of Fiber and there output

14. Note the input of the fiber on the previous slide for multimode fibers • Now look at the output. See how the light pulse (photons) spread at the output. This is call modal dispersion. • The output is no longer squared off but looks like a bell curve. • The photons that travel straight through get to the end the quickest and that is where you see the output level first start coming up on the right side of the bell curve. • The photons that ricochet the most get to the end last and form the left side of the bell curve. • The majority fall in the middle of the curve.

19. Plastic versus glass • POF has been called the "consumer" optical fiber because the fiber and associated optical links, connectors, and installation are all inexpensive. • The traditional plastic fibers are commonly used for low-speed, short-distance (up to 100 meters) applications in digital home appliances, home networks, industrial networks (PROFIBUS, PROFINET), and car networks. • Glass - This fiber has a core made of germania-doped silica. Although the actual cost of glass fibers are lower than plastic fiber, their installed cost is much higher due to the special handling and installation techniques required but, greater distances and higher bandwidth are provided---

20. Qualifier – in labs now • Thanks to a new technique for data transmission, they have actually succeeded in transmitting one gigabit per second over a 100 meter long test route in the laboratory – without errors or flickering on the screen. • Thanks to quadrature amplitude modulation with up to 256 signal states, the so-called bandwidth efficiency measured in bits per second and hertz can be increased significantly,” explained Sebastian Randel, project manager at Siemens Corporate Technology. Thanks to their algorithm, the researchers could finally transmit exactly 1008 megabits per second through a polymer fiber cable.

21. Single mode versus Multimode • Single mode • up to 40Gbs with WDM http://en.wikipedia.org/wiki/Wavelength-division_multiplexing • harder to terminate • Factory recommend terminations • Long haul applications • Mulitmode • up to Gbs speeds • on site termination • Gigabit to 275m to 2km • Modal dispersion limits multimode fiber use to relatively short runs--typically no more than a few hundred meters at gigabit ethernet

22. Video coax to fiber transceivers $735 10/100/1000 Media Converters $69.50 10/ 100 Media Converter

23. UWGB Campus configuration • 62.5 multimode between closets • Some composite cables – both single mode and multimode fibers. Single mode for future expansion • strands vary between 6 and 24 count • Telecom closet to server farm (MDF or equipment room) Fiber feeds the switches • Telecom closet – where the switches are located • Switches to workstations – copper • FTTD? when

24. SONET – at a very high level • Synchronous Optical Network - SONET • State wide system • Singlemode • OC 3 or higher depending on leg • SONET rings, known as "self-healing rings," use two or more transmission paths between network nodes, which are typically digital cross-connects (DCSs) or add/drop multiplexers (ADMs). If there is a break in one line, the other may still be available, providing the second is not in close proximity to the first and also damaged.

25. SONET Ring: All data is transmitted on the working or active path, while the standby path (protection path) lies in waiting. When a failure in the active path occurs, the two network nodes affected immediately switch to the standby line.

26. Multiplexing • WMD (no not that WMD) • Multiplexing of multiple optical carriers by using different wavelengths (colors) of laser light to carry different signals. • WDM wavelengths are positioned in a grid having exactly 100 GHz (about 0.8nm) spacing in optical frequency, with a reference frequency fixed at 193.10 GHz (1552.52nm). • Modern systems can handle up to 160 signals and can thus expand a basic 10 Gbs fiber system to a theoretical total capacity of over 1.6 Tbs over a single fiber pair. • Form of FDM • Reference is made to the varying wavelength of the laser light rather than frequency • A WDM system uses a multiplexer at the transmitter to join the signals together, and a de-multiplexer at the receiver to split them apart.

27. DWDM • DWDM works by combining and transmitting multiple signals simultaneously at different wavelengths on the same fiber. In effect, one fiber is transformed into multiple virtual fibers. • Currently, because of DWDM, single fibers have been able to transmit data at speeds up to 400Gb/s. • Commercial systems capable of carrying 128 signals, DWDM systems use 50 GHz or even 25 GHz channel spacing for up to 160 channel operation • The difference between WDM and dense wavelength division multiplexing (DWDM) is fundamentally one of only degree. DWDM spaces the wavelengths more closely than does WDM, and therefore has a greater overall capacity.

28. Assignment • Develop a fiber related question on termination, speeds, type of fiber, ... • Post question to the discussion section on the wiki page Digital Communications Fall 2009 • Answer questions of two other classmates by Tuesday the following week at midnight – December 1st. • Lab on December 2nd will be terminating Fiber cables!