A solution to this problem was explored in the form of efficient frequency multipliers, optical devices that combine several photons into one of higher energy, and thus frequency.
12.
For example, if the phase locked loop were to implement a frequency multiplier, the oscillator signal could be divided in frequency before it is compared to the reference signal.
13.
This is typically addressed through the use of an optical frequency multiplier, which can double or triple the frequency of the light, into the green or ultraviolet, respectively.
14.
In this field varactor diodes are used as a voltage variable capacitor in frequency multipliers, parametric amplifiers and variable junction when reverse biased which is the source of the capacitor effect.
15.
The mixer circuit can be used not only to shift the frequency of an input signal as in a receiver, but also as a product detector, modulator, phase detector or frequency multiplier.
16.
In electronics, a "'frequency multiplier "'is an electronic circuit that generates an output nonlinear circuit that distorts the input signal and consequently generates harmonics of the input signal.
17.
It can be more economical to develop a lower frequency signal with lower power and less expensive devices, and then use a frequency multiplier chain to generate an output frequency in the microwave or millimeter wave range.
18.
ICF research turned to using an " optical frequency multiplier " to convert the incoming IR light into the ultraviolet at about 351 nm, a technique that was well known at the time but was not efficient enough to be worthwhile.
19.
An "'optical frequency multiplier "'is a nonlinear optical device in which photons interacting with a nonlinear material are effectively " combined " to form new photons with greater energy, and thus higher frequency ( and shorter wavelength ).
20.
At each step of the chain, a frequency multiplier would be used to produce a harmonic of the frequency of that step, which would be compared by heterodyne detection with the next step ( the output of a microwave source, far infrared laser, infrared laser, or visible laser ).
