1 / 6

Snell’s Law

. n 1. n 2. . n 1. . Light rays bend when traversing boundaries between media with different refractive index:. in. out. Snell’s Law. See http://micro.magnet.fsu.edu/primer/java/scienceopticsu/refraction/index.html. Optical fiber. n > n’ always. size. Cladding. ~ 100 μ m. n’.

virote
Download Presentation

Snell’s Law

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. n1 n2  n1  Light rays bend when traversing boundaries between media with different refractive index: in out Snell’s Law See http://micro.magnet.fsu.edu/primer/java/scienceopticsu/refraction/index.html

  2. Optical fiber n > n’ always size Cladding ~ 100 μm n’ 1 – 10 μm Core n n’ n’ n’ n’ n n Cross-section n’ n’ Optical fibers are cylindrical waveguides, providing light confinement by total internal reflection along all directions which are perpendicular to the propagation direction. These are essentially bendable “light pipes”.

  3. Optical loss in fiber-quality fused silica. (circa 1995) Fibers are made of ultrapure SiO2 glass (silica). Different dopants are added both to the core and cladding, such that the refractive index of the core is slightly larger than that of the cladding. Communications window Optical loss in fiber-quality fused silica. (circa 2001) To optimize fibers for telecommunications applications it was necessary to purify them to a very high degree and remove all traces of water. This eliminated the high absorption losses in the “communications window”.

  4. Fiber-Optic Communications Systems Laser Light pulses travel in fiber (short or long) Output electric pulses Input electric pulses ~10Gb/sec Example of fiber-optical communication link. Electrical current pulses representing digital data drive a semiconductor laser. The emitted light pulses pass through a fiber and are detected by a photo-detector at the far end.

  5. Communications window Amplifying optical signals How far can an optical signal (light) travel in fiber before absorption causes significant losses and signal deterioration? Fibers can typically transmit information over a distance of 80km, after which signals require amplification and/or regeneration. Fibers also have a very large bandwidth – the communications window where absorption losses in the fiber are small is broad. This allows transmitting many wavelengths (frequencies) simultaneously.

  6. Connecting fibers – optical communications systems Different frequency for each channel MUX = Multiplexing DEMUX = Demultiplexing SCL = semiconductor laser Mod = modulator Det = detector

More Related