Optical modulators using semiconductor nano-structures: Difference between revisions

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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:opticalAcousto-optic mod3Modulator.jpgpng]]

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

Acoustic [[solitons]] strongly influence the electron states in a semiconductor nanostructure. The amplitude of [[soliton]] pulses is so high that the electron states in a [[quantum well]] make temporal excursions in energy up to 10 meV. The subpicosecond duration of the [[solitons]] is less than the coherence time of the optical transition between the electron states and a frequency modulation of emitted light during the coherence time (chirping effect) is observed. This system is for an ultrafast control of electron states in semiconductor nanostructures.

=== Magneto-optic modulator of nano-structures ===