transmit the information
the basic limitation on direct modulation rate of laser diodes depend on the spontaneous emission stimulated emission carrier life time. and these limitation can be taken care by semiconductor band gap and the carrier concentration.
It is used to delay the modulation
because english is the international communicaton language
Rhett Truesdale George has written: 'An experimental study of frequency modulation of the laser by the Zeeman effect' -- subject(s): Radio frequency modulation, Magnetooptics, Lasers
Frequency modulation have some advantages over amplitude modulation, FM is not sensitive to the amplitude noise, and have high efficient use of transmitted power
It uses GFSK (Gaussian Frequency Shift Keying) modulation technique.
i am goiing to frhiill
When modulated with a radio frequency signal, they will indeed carry information. As in fibre-optic cables. The modulation may be of the several commonly used types, amplitude, frequency, phase ... modulation.
You can bend the beam of a laser with sound using a technique called acousto-optic modulation. This involves passing the laser beam through a medium that is being vibrated at the frequency of the sound wave. The sound wave changes the refractive index of the medium, causing the laser beam to bend.
Modulation is only required if the data is being sent over a radio wave, or a laser beam. And even in the case of a laser, if you are content with on/off data streams, then there is no underlying signal to be modulated. Essentially all of the data whizzing round in your computer is doing so without the benefit(?) of a carrier - the wires are sufficient.
Some examples of applications of phase modulators are: * A phase modulator within a laser resonator of a single-frequency laser can be used for wavelength tuning, or for active mode locking (FM mode locking) of a laser. * A phase modulation of a beam with moderate modulation strength is often used in laser frequency stabilization schemes, e.g. with the Pound-Drever-Hall method. * Various kinds of interferometers and setups for spectroscopic measurements require phase modulators, often with a periodic drive signal. * Some metrology applications require frequency combs, generated by sending a single-frequency beam into a phase modulator. In that case, the phase modulation often needs to be strong in order to obtain a large number of optical sidebands. * In data transmitters of optical fiber communication systems, phase modulators can be used for encoding the transmitted information. An example is the method of phase shift keying. Source: http://www.rp-photonics.com/phase_modulators.html
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