Frequency Comb Generation
Modelocked lasers produce a series of optical pulses separated in time by the round-trip time of the laser cavity. The spectrum of such a pulse train approximates a series of Dirac delta functions separated by the repetition rate (the inverse of the round trip time) of the laser. This series of sharp spectral lines is called a frequency comb or a frequency Dirac comb.
A purely electronic device, which generates a series of pulses, also generates a frequency comb. These are produced for electronic sampling oscilloscopes, but also used for frequency comparison of microwaves, because they reach up to 1 THz. Since they include 0 Hz they do not need the tricks which make up the rest of this article.
Read more about this topic: Frequency Comb
Famous quotes containing the words frequency, comb and/or generation:
“The frequency of personal questions grows in direct proportion to your increasing girth. . . . No one would ask a man such a personally invasive question as “Is your wife having natural childbirth or is she planning to be knocked out?” But someone might ask that of you. No matter how much you wish for privacy, your pregnancy is a public event to which everyone feels invited.”
—Jean Marzollo (20th century)
“So summer comes in the end to these few stains
And the rust and rot of the door through which she went.
The house is empty. But here is where she sat
To comb her dewy hair, a touchless light,
Perplexed by its darker iridescences.”
—Wallace Stevens (1879–1955)
“The very nursery tales of this generation were the nursery tales of primeval races. They migrate from east to west, and again from west to east; now expanded into the “tale divine” of bards, now shrunk into a popular rhyme.”
—Henry David Thoreau (1817–1862)