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An electro-optic modulator (EOM) is an optical device in which a signal-controlled element exhibiting an electro-optic effect is used to modulate a beam of light. The modulation may be imposed on the phase , frequency , amplitude , or polarization of the beam.
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. According to manipulation of the properties of material modulators are divided into two groups, absorptive modulators ( absorption coefficient ) and ...
An optical modulator is a device which is used to modulate a beam of light. The beam may be carried over free space, or propagated through an optical waveguide ( optical fibre ). Depending on the parameter of a light beam which is manipulated, modulators may be categorized into amplitude modulators, phase modulators, polarization modulators, etc.
An electro-absorption modulator (EAM) is a semiconductor device which can be used for modulating the intensity of a laser beam via an electric voltage. Its principle of operation is based on the Franz–Keldysh effect, i.e., a change in the absorption spectrum caused by an applied electric field, which changes the bandgap energy (thus the photon energy of an absorption edge) but usually does ...
The electro-optic Pockels effect in nonlinear crystals (e.g. KDP, BSO, K*DP) can be used for electric field sensing via polarisation state modulation techniques. In this scenario, an unknown electric field results in polarisation rotation of a laser beam propagating through the electro-optic crystal; through inclusion of polarisers to modulate ...
Tunable lasers are sometimes used in combination with coherent modulation to allow a module to support various forms of network-based optical switching such as needed in certain cases by an optical mesh networks or a Reconfigurable optical add-drop multiplexer (ROADM). In these, the transmit laser can be tuned to a different optical frequency ...
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An acousto-optic modulator (AOM), also called a Bragg cell or an acousto-optic deflector (AOD), uses the acousto-optic effect to diffract and shift the frequency of light using sound waves (usually at radio-frequency). They are used in lasers for Q-switching, telecommunications for signal modulation, and in spectroscopy for frequency