Lasers: coherent sources of light
Glass fibers with low optical attenuation
Human-made vs. Natural Sources of Electromagnetic Radiation (coherent vs. incoherent light sources)The classical picture of light emission: Radiating lines of force from an oscillating charge (Review Lecture 6)
The quantum mechanical picture of light emission: Absorption and Emission of Radiation by an Atom (applet)
Coherent radiation: a continuous source (sharp spectral lines)
Incoherent radiation: a discontinuous or interrupted source (broad spectral lines)
Lasers: sources of fairly coherent radiationGiven the "quantum nature" of atomic emission, how do we get a fairly continuous source?Answer: We induce a cooporative emission process. The Laser: Demonstration (applet)The WWSR Laser Tutorial gives a very nice picture of how the whole thing works.The key idea is that "population inversion" leads to "stimulated emission of radiation."Other interesting, but more advanced demonstrations of laser operation from Physics Education Research Group at Kansas State University (KSU).The Laser Adventure by Rami Arieli
On-Line Interactive Programs
Ruby Laser (No longer available online)
Helium Neon Laser (No longer available online)
Diode Laser (No longer available online)
Why does a hollow pipe light guide work? Problem - beam divergence (the smaller the beam the faster it diverges) and loss at reflecting walls (diagram). See schematic of a famous BTL version of an operational light pipe (circa 1960).
Light rays at an interface: (diagram)Reflection - Law of Specular ReflectionMore on total internal reflection:
Refraction - Law of Snell
Total internal reflectionA wonderful Total Internal Reflection (TIR) applet.Fiber characteristics:
Two figures from the Schott tutorial The Properties of Light Applied to Fibre Optics: (figure 1 and figure 2)Types of optical fibres and their manufacture: from Schott tutorial (figure)Attenuation:
Geometry of typical single-mode and multimode optical fibers - after Paul E. Green. Jr. (figure)
Standard AT&T 144-fiber cable. Typical cable used for intercity transmission. - after S.E. Miller & I.P. Kaminow. (figure)
Radial index profiles of typical single-mode and multimode optical fibers. - after Suzanne R. Nagel. (figure)Data on AttenuationDispersion: (velocity dependence on frequency/wavelength)
Data on Dispersion
Review modulation schemes: FDMA (WDMA) and TDMA
Two figures from Web ProForum tutorials on DWDM: (figure 1 and figure 2)
Two switching ideas: (figure 1 and figure 2)
Hybrid Fiber/Coaxial Cable (HFCC)
Schematic Multiloop Network (OC-193)
Alexander Graham Bell in 1880 reported the transmission of speech over 200 meter by modulating sunlight with a reflecting diaphragm ("photophone")
To avoid the degradation of optical signals in the atmosphere, Kao and Hockman in England (and simultaneously Wirt in France) in 1966 suggested the use of dielectric wave guides or optical fibers.
Historical reduction of optical loss - after Suzanne R. Nagel.
Increase in bit rate-distance product during the years 1850-2000. The emergence of a new technology is marked by a filled circle - after Govind P. Agrawal.
Progress in lightwave communication technology over the period 1974-1992. Different curves show the increase in the bit rate-distance product for five generations of fiber-optic communication systems - after Govind P. Agrawal.
A Short History of Fiber Optics by Jim Hayes
A Fiber-Optic Chronology by Jeff Hecht
A Brief History of Optics
A general Glass History: from Iowa State University
Fiber Optics Basics: by Terry Macy at Ohio University
Fiber Optics Basics: a tutorial which emphasizes cable configurations - from LASCOMM
Fibre Optic Technologies: from Mercury Communications Ltd
Two Web ProForum tutorials on DWDMDense wavelength division multiplexing (DWDM) tutorial
Dense wavelength division multiplexing (DWDM) testing tutorials