Fiber Optics Nov 21, 2002. Announcements One lecture left in the semester –Next class, Dec 5 - Wireless System –Suggested problems to prepare for Final.

Fiber Optics

Nov 21, 2002

Announcements• One lecture left in the semester

– Next class, Dec 5 - Wireless System – Suggested problems to prepare for Final Exam

(not Homework)

– Chapter 16: 3, 7, 12, 16, 18, 24, 28

– Chapter 18: 2, 8, 10, 12, 16, 17, 24

• Final Exam: Dec 12

Announcements• Final Exam: Dec 12

– Will cover the complete semester course material• Chapters 16 and 18 in detail• Fundamental concepts discussed thoughout the semester

– Approximately 2 hours to complete– Required formulas will be provided– Bring calculator– If unable to be present for the test then the same rules

apply:• Previous notification is needed due to work and/or travel• Being absent does not give right to make-up test• If you have an acceptable reason for your unplanned absence,

then an Incomplete will be assigned as the grade

Objectives

• Understand basic principles of fiber optic communications.

Fiber Optics Characteristics

• Advantages– Bandwidth– Less Loss– Noise Immunity– Less Weight and Volume– Security– Flexibility– Economics– Reliability

Fiber Optics Characteristics (cont.)

• Disadvantages– Interfacing Costs– Strength– Remote Powering of Devices

FIGURE 18-2 Simplified optical telecommunications system.

Warren HiokiTelecommunications, Fourth Edition

Copyright ©2001 by Prentice-Hall, Inc.Upper Saddle River, New Jersey 07458

All rights reserved.

Theory of Light

• Light has the characteristics of both propagating waves and particles

• The energy of a light particle is called a photon, and it is related to the frequency (Planck’s Law)

• The wavelengths of light are very small

• It is harder to generate and control light than it is for electric signals

Wavelength

• The relationship between the wavelength and frequency for electromagnetic waves is given by: = F/C where:– is the wavelength in meters– F is the frequency in Hertz (cycles/second)– C is the speed of light in a vacuum = 3 x 108

meters/second

FIGURE 18-4 Electromagnetic spectrum showing the approximate boundaries between spectral regions. (Courtesy of RCA.)







FIGURE 18-5 A light ray incident on the surface of water is bent toward the normal.




FIGURE 18-6 (a) A light ray enters a glass plate and is bent toward the normal. Its speed is reduced. As it emerges from the glass plate, it is bent away from the normal and returns to its original speed. (b) A light ray is bent toward the normal as it enters a lens. As it exits the lens, it is bent away from the normal.







FIGURE 18-7 A light ray is incident on the surface of water at an angle of 52° with respect to the normal. The light ray refracts toward the normal as it enters the more dense medium of water.




Look at examples

• Repeat example with different materials with varying index of refraction.

FIGURE 18-8 Light entering a medium whose index of refraction is less than the medium from which it exits will refract away from the normal unless the angle of incidence exceeds the critical angle. When this occurs, as in Example 18.4, total internal reflection occurs.




FIGURE 18-9 Light rays are transmitted into a glass slab surrounded by air. Ray A exceeds the critical angle and experiences total internal reflection. Ray B is less than the critical angle. Total internal reflection does not occur. A portion is reflected back into the glass, and a portion exits the glass into air and refracts away from the normal.




FIGURE 18-10 A light ray is transmitted into the core of an optical fiber strand. The critical angle between the glass core and its cladding is exceeded; therefore, total internal reflection occurs.




FIGURE 18-11 Transmission modes shown for various rays of light.




FIGURE 18-12 Three major classifications of optical fibers and their index profiles: (a) multimode step index; (b) single-mode step index; (c) multimode graded index. (Courtesy of AMP Incorporated.)




FIGURE 18-13 Multimode graded-index fiber. Ray 1 travels much less distance than ray 2; however, ray 2 increases in velocity as it propagates farther away from the core. This is caused by the graded index of the fiber. Ray 2 makes up in distance by its increase in velocity. Pulse spreading is minimized.




FIGURE 18-14 Wavelength-Division Multiplexing (WDM) combines multiple optical signals at different wavelengths and transports them over a single fiber.




FIGURE 18-15 Basic construction of a fiber-optic cable. (Courtesy of Hewlett-Packard Optical Communication Division.)




FIGURE 18-16 Various optical fiber cable configurations: (b) Remfo’s series 10 light-duty construction indoor simplex cable (courtesy of Remfo Fiber Optic Division); (c) Remfo’s series 12 indoor/outdoor multifiber cable (courtesy of Remfo Fiber Optic Division).







FIGURE 18-19 Radiation losses occur in microbends or macrobends: (a) Microbending occurs when there are miniature bends and geometric imperfections along the axis of the fiber; (b) macrobending occurs when a fiber is bent to a radius that is less than the fiber’s minimum bend radius (typically 10 to 20 cm).




FIGURE 18-20 Acceptance cone for measuring NA. (Courtesy of Hewlett-Packard Optical Communication Division.)




FIGURE 18-22 Various tube splices: (a) snug tube splice; (b) loose tube splice; (c) transparent capillary tube.




FIGURE 18-26 Four major extrinsic losses that can occur in a fiber connection. (Courtesy of AMP Incorporated.)




FIGURE 18-27 Radiation patterns for: (a) LED; (b) ILD.




FIGURE 18-28 Comparison of special widths between the fiber-optic LED and ILD.







FIGURE 18-29 Construction of various LEDs: (a) S-PUP (Silox P side up) emitter, 820 nm (surface LED); (b) enhanced emitter design, 820 nm; (c) etched-well emitter, 820 nm; (d) 1300-nm emitter. (Courtesy of Hewlett-Packard Optical Communication Division.)




FIGURE 18-30 Construction of the injection laser diode. (Reprinted with permission from Hewlett-Packard.)




FIGURE 18-31 Typical injection laser diodes.




FIGURE 18-32 Structure of the PIN photodiode. (Reprinted with permission from Hewlett-Packard.)




FIGURE 18-33 Hewlett-Packard’s HFBR-2208 PIN photodiode receiver. (From Hewlett-Packard Optoelectronics Designer’s Catalog, 1988–1989, pp. 8–98.)




Fiber Optics Nov 21, 2002. Announcements One lecture left in the semester –Next class, Dec 5 - Wireless System –Suggested problems to prepare for Final.

Documents

new jersey

upper saddle river

warren hiokitelecommunications

speed of light

light ray incident

light particle

control light

surface of water