Optical modulators using semiconductor nano-structures: Difference between revisions

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{{orphan|date=September 2010}}

An [[optical modulator]] is an optical device which is used to modulate a beam of light with a perturbation device. It is a kind of transmitter to convert information to optical binary signal through [[optical fiber]] ([[optical waveguide]]) or transmission medium of optical frequency in fiber optic communication. There are several methods to manipulate this device depending on the parameter of a light beam like [[amplitude modulator]] (majority), [[phase modulator]], polarization modulator etc.

The easiest way to obtain modulation is modulation of intensity of a light by the current driving the light source ([[laser diode]]). This sort of modulation is called direct modulation, as opposed to the external modulation performed by a light modulator. For this reason, light modulators are called external light modulators.

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In an AOM a laser beam is caused to interact with a high frequency ultrasonic sound wave inside an optically polished block of crystal or glass (the interaction medium). By carefully orientating the laser with respect to the sound waves the beam can be made to reflect off the acoustic wave-fronts ([[Bragg diffraction]]). Therefore, when the sound field is present the beam is deflected and when it is absent the beam passes through undeviated. By switching the sound field on and off very rapidly the deflected beam appears and disappears in response (digital modulation). By varying the amplitude of the acoustic waves the intensity of the deflected beam can similarly be modulated (analogue modulation).

[[File:Acousto-optic Modulator-en.pngsvg]]

Acoustic [[solitons]] in semiconductor nanostructures<ref>Journal of Physics: Conference Series 92 (PHONONS 2007)</ref>

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* from THORLABS

40 &nbsp;Gbit/s Phase Modulator

The 40 &nbsp;Gbit/s Phase Modulator is a high performance, low drive voltage External Optical Modulator designed for customers developing next generation 40G transmission systems. The increased bandwidth allows for chirp control in high-speed data communications.

Applications ; Chirp Control for High-Speed Communications (SONET OC-768 Interfaces, SDH STM-256 Interfaces), Coherent communications, C & L Band Operation, Optical Sensing, All-optical frequency shifting.

* from Mach-40

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=== Acousto-optic modulator of nano-structures ===

Applications ; acousto-optic modulators include laser printing, video disk recording, laser projection systems.

* from ELECTRO-OPTICAL PRODUCTS CORPORATION