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For example, 23 dBm correspond to 10 2.3 × 1 mW = 200 mW.
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of the saturated output power of a fiber amplifier. This is often used to specify absolute power levels, e.g. dBm = dB relative to a reference power of 1 mW.The 60-dB difference reflects the bandwidth reduction by a factor of 10 6. For example, if one obtains −25 dBc in a 1-MHz bandwidth, this converts into −85 dBc in 1 Hz, i.e., −85 dBc/Hz. Often, such specifications are calculated from measurements based on a larger bandwidth.(Of course, this does not mean that there would be twice as many dBc in a 2-Hz bandwidth, as decibels are a logarithmic measure therefore an interpretation as “dBc per hertz” would not be appropriate!).dBc/Hz: This is used for noise and means dBc in a 1-Hz bandwidth.For example, −30 dBc means that the sideband is 30 dB below the carrier, i.e., it has a 1000 times lower power. to specify the power of a sideband in a modulated signal relative to the carrier. Some frequently used related specifications are: Therefore, 3 dB more optical input power leads to 6 dB more signal power. When the optical input power is doubled while the modulation remains unchanged, the signal power (modulation power) will be increased by a factor of 4. in cases with intensity (power) modulation the signal power is then again related to the square of the signal amplitude and can thus have units of W 2 (watts squared). However, one may also take the signal to be an optical power, e.g. If the signal is an electrical voltage or current, the signal power corresponds to an electrical power delivered to a given impedance (e.g. Geräusche bis zu 15 Dezibel sind vom menschlichen Ohr kaum wahrnehmbar. Dabei verhält es sich zunächst so: Je mehr Dezibel etwas aufweisen kann, desto lauter wird es auch von uns empfunden. The modulation power is proportional to the square of the signal amplitude. Dezibel (dB) ist ein Ausdruck, mit dem weltweit die Lautstärke eines Geräusches angegeben werden kann.with modulation of the optical phase, the optical power is not directly relevant for the signal.
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In the case of direct detection with a photodetector, this is translated into an electrical photocurrent or voltage.