What do you imagine when you hear the word “opto-electronics”?
Opto-electronics is a word combining optics and electronics, mainly used in Japan.
American people prefer to use a term “optronics” or “electro-optics”.
This academic field covers broad concepts involving light emitting devices and elements, information displays, image pickup devices, optical storages, optical communications, remote sensing systems and so on.
Laser is an abbreviation of a word string. Spell it out.
Light Amplification by Stimulated Emission of Radiation
“Stimulated emission”antonym of “spontaneous emission”
optical transition stimulated by the effect of electric field of light wave
on the contrary usually emission occur spontaneously without help of electric field
on the contrary usually emission occur spontaneously without help of electric field
How the light is transmitted through optical fiber.
Light is transmitted along the core by total reflection mechanism at the boundary with the cladding layer
Development of Communication
Trend of increase in data carrying capacity
Trend of increase in data carrying capacity
To meet with the growing need for large capacity information exchange, optical fiber communication system has been developed.
Broadband and Narrow band
Recently we hear the word “broadband”. What does the “broadband” mean?
Broadband stands for broad bandwidth in communication path. The band width is defined in the frequency domain, the broader the frequency region for communication the larger is the capacity of information.
The broadness of communication path is expressed in terms of bit transfer rate, the unit being bps=bit per second.
Analog telephone line with metallic cable has a bit rate of 56 kbps, while digital telephone (ISDN=integrated service digital network) line has a rate of 128 kbps. These are called “narrowband” systems.
On the contrary, even metallic line can have higher rate by using ADSL (asymmetric digital subscriber line) which has asymmetric data rate of 1.5Mbps to 50 Mbps for downward steam, and 12kbps to 3 Mbps for upward steam. Higher rate is provided only for close area from station.
FTTH (fiber to the home) supports 100Mbps for both up and down stream.
Optical fiber is becoming the leading actor of information network
FTTH can transfer as large as100Mbit=13MB information per second
It means you take only one minute to download information on one CD sheet（~640MB）
