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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 ...
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 ...
Load Modulation is a method of conveying a signal from one device to another by means of modulating the load that the transmitting device imposes on a radio signal provided by the receiving device. This is used, for example, to allow ISO/IEC 14443 and ISO/IEC 15693 NFC cards to reply to the reading device without the need for the NFC card to ...
The output of the photodetector is amplified and filtered and fed back to the electric port of the modulator. This configuration supports self-sustained oscillations, at a frequency determined by the fiber delay length, the bias setting of the modulator, and the band pass characteristics of the filter. It also provides for both electric and ...
A modified constellation diagram of 16-APSK. Typically 16-APSK will have 15 degree phase offset on the outer ring, which is not depicted here. Symbols can be easily distinguished from each other and, moreover, varying of the space between rings is a way to counteract transmission distortions. [4]
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In telecommunications, an eye pattern, also known as an eye diagram, is an oscilloscope display in which a digital signal from a receiver is repetitively sampled and applied to the vertical input (y-axis), while the data rate is used to trigger the horizontal sweep (x-axis). It is so called because, for several types of coding, the pattern ...