From Wikipedia, the free encyclopedia. Optical heterodyne detection is a method of extracting information encoded as modulation of the phase, frequency or both of electromagnetic radiation in the wavelength band of visible or infrared light.
What is a heterodyne system?
A heterodyne is a signal frequency that is created by combining or mixing two other frequencies using a signal processing technique called heterodyning, which was invented by Canadian inventor-engineer Reginald Fessenden. Heterodyne frequencies are related to the phenomenon of “beats” in acoustics.
What is optical coherent detection?
Coherent detection allows information to be encoded with two degrees of freedom, which increases the amount of information per channel. From: Optical Fiber Telecommunications VII, 2020.
What is homodyne and heterodyne detection?
In radio technology, the distinction is not the source of the local oscillator, but the frequency used. In heterodyne detection, the local oscillator is frequency-shifted, while in homodyne detection it has the same frequency as the radiation to be detected.
What is purpose of mixing of signals in a heterodyne receiver?
The principle of this technique is to mix the optical received signal with a local optical oscillator in order to provide an electrical signal at an intermediate frequency. This electrical signal then passes through a very narrow electrical filter to reduce the noise power.
Why is it called super heterodyne?
This is the same effect that Fessenden had proposed, but in his system the two frequencies were deliberately chosen so the beat frequency was audible. In this case, all of the frequencies are well beyond the audible range, and thus “supersonic”, giving rise to the name superheterodyne.
What is a heterodyne frequency meter?
[′hed·ə·rə‚dīn ′frē·kwən·sē ‚mēd·ər] (electronics) A frequency meter in which a known frequency, which may be adjustable or fixed, is heterodyned with an unknown frequency to produce a zero beat or an audio-frequency signal whose value is measured by other means.
What is the purpose of super heterodyne?
A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency.
What is super heterodyne method?
The superheterodyne receiver is the most common configuration for radio communication. Its basic principle of operation is the translation of all received channels to an intermediate frequency (IF) band where the weak input signal is amplified before being applied to a detector.
What is the difference between optical heterodyne detection and mixing product?
Optical heterodyne detection involves optical signal and local oscillator waves, whereas the mixing product is an electrical signal. The mixing product is not obtained by mixing the signal and local oscillator wave in a nonlinear crystal, but rather simply by detecting the linearly superimposed waves…
What is the electric power of heterodyne signal?
Its electric power is proportional to the product of the optical powers of signal and local oscillator. With a strong local oscillator, the heterodyne signal resulting from a weak input signal can be much more powerful than for direct detection.
What is heterodyne and homodyne spectroscopy used for?
This can be useful for precision laser spectroscopy, for example. A variant of heterodyne detection is homodyne detection, where the local oscillator frequency equals the signal frequency. For optical homodyne measurements, both waves are virtually always derived from the same laser source.
What is heterodyning in optical Kerr effect spectroscopy?
In optical Kerr effect (OKE) spectroscopy, optical heterodyning of the OKE signal and a small part of the probe signal produces a mixed signal consisting of probe, heterodyne OKE-probe and homodyne OKE signal. The probe and homodyne OKE signals can be filtered out, leaving the heterodyne frequency signal for detection.
