A comb generator is a

signal generator A signal generator is one of a class of Electronics, electronic devices that generates electrical signals with set properties of amplitude, frequency, and wave shape. These generated signals are used as a stimulus for electronic measurements, typ ...

that produces multiple

harmonic In physics, acoustics, and telecommunications, a harmonic is a sinusoidal wave with a frequency that is a positive integer multiple of the ''fundamental frequency'' of a periodic signal. The fundamental frequency is also called the ''1st har ...

s of its input signal. The appearance of the output at the

spectrum analyzer A spectrum analyzer measures the magnitude of an input signal versus frequency within the full frequency range of the instrument. The primary use is to measure the power of the spectrum of known and unknown signals. The input signal that most co ...

screen, resembling teeth of a

comb A comb is a tool consisting of a shaft that holds a row of teeth for pulling through the hair to clean, untangle, or style it. Combs have been used since prehistoric times, having been discovered in very refined forms from settlements dating ba ...

, gave the device its name. Comb generators find wide range of uses in

microwave Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequency, frequencies between 300&n ...

technology. E.g., synchronous signals in wide frequency bandwidth can be produced by a comb generator. The most common use is in broadband

frequency synthesizer A frequency synthesizer is an electronic circuit that generates a range of frequencies from a single reference frequency. Frequency synthesizers are used in devices such as radio receivers, televisions, mobile telephones, radiotelephones, walkie ...

s, where the high frequency signals act as stable references correlated to the lower energy references; the outputs can be used directly, or to synchronize

phase-locked loop A phase-locked loop or phase lock loop (PLL) is a control system that generates an output signal whose phase is fixed relative to the phase of an input signal. Keeping the input and output phase in lockstep also implies keeping the input and ou ...

oscillator Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...

s. It may be also used to generate a complete set of substitution channels for testing, each of which carries the same baseband audio and video signal. Comb generators are also used in RFI testing of

consumer electronics Consumer electronics, also known as home electronics, are electronic devices intended for everyday household use. Consumer electronics include those used for entertainment, Communication, communications, and recreation. Historically, these prod ...

, where their output is used as a simulated RF emissions, as it is a stable broadband noise source with repeatable output. It is also used during compliance testing to various government requirements for products such as medical devices (FDA), military electronics (

MIL-STD-461 MIL-STD-461 is a United States Military Standard A United States defense standard, often called a military standard, "MIL-STD", "MIL-SPEC", or (informally) "MilSpecs", is used to help achieve standardization objectives by the United States Depa ...

), commercial avionics (Federal Aviation Administration), digital electronics (

Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency of the United States government that regulates communications by radio, television, wire, internet, wi-fi, satellite, and cable across the United States. The FCC maintains j ...

), in the USA. An optical comb generator can be used as generators of

terahertz radiation Terahertz radiation – also known as submillimeter radiation, terahertz waves, tremendously high frequency (THF), T-rays, T-waves, T-light, T-lux or THz – consists of electromagnetic waves within the International Telecommunicat ...

. Internally, it is a resonant electro-optic modulator, with the capability of generating hundreds of

sideband In radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency, that are the result of the modulation process. The sidebands carry the information transmitted by the radio signal. The sidebands c ...

s with total span of at least 3 terahertz (limited by the

optical dispersion Dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency. Sometimes the term chromatic dispersion is used to refer to optics specifically, as opposed to wave propagation in general. A medium having this common ...

of the

lithium niobate Lithium niobate () is a synthetic salt consisting of niobium, lithium Lithium (from , , ) is a chemical element; it has chemical symbol, symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard temperatur ...

crystal) and frequency spacing of 17 GHz. Other construction can be based on erbium-doped

fiber laser A fiber laser (or fibre laser in Commonwealth English) is a laser in which the active gain medium is an optical fiber doped with rare-earth elements such as erbium, ytterbium, neodymium, dysprosium, praseodymium, thulium and holmium. They ar ...

Ti-sapphire laser A titanium-sapphire laser (also known as a Ti:sapphire laser, Ti:Al2O3 laser or Ti:sapph) is a tunable laser which emits red and near-infrared light in the range from 650 to 1100 nanometers. This type of laser is mainly used in scientific research ...

often in combination with

carrier envelope offset control A frequency comb or spectral comb is a spectrum made of discrete and regularly spaced spectral lines. In optics, a frequency comb can be generated by certain laser sources. A number of mechanisms exist for obtaining an optical frequency comb, in ...

References

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External links

Yet another comb generator

Com-Power Corporation

Com-Power Corporation
Laboratory equipment Electronic test equipment Signal processing Terahertz technology

See also

References

External links