RP Photonics logo
RP Photonics
Encyclopedia
Consulting Software Encyclopedia Buyer's Guide

Short address: rpp-con.com

Dr. Paschotta, the founder of RP Photonics, supports your R & D with his deep expertise. Save time and money with efficient support!

Short address: rpp-soft.com

Powerful simulation software for fiber lasers and amplifiers, resonator design, pulse propagation and multilayer coating design.

Short address: rpp-enc.com

The famous Encyclopedia of Laser Physics and Technology provides a wealth of high-quality scientific and technical information.

Short address: rpp-bg.com

In the RP Photonics Buyer's Guide, you easily find suppliers for photo­nics products. As a supp­lier, you can profit from enhanced entries!

Learn on lasers and photonics every day!
VL logo part of the
Virtual
Library

Sum and Difference Frequency Generation

<<<  |  >>>  |  Feedback

Buyer's Guide

The ideal place to find suppliers for photonics products: high-quality information, simple and fast, respects your privacy!

7 suppliers for equipment for sum and difference frequency generation are listed.

Your are not yet listed? Get your entry!

Ask RP Photonics for advice concerning the design of sum or difference frequency generation stages.

Acronym: SFG, DFG

Definition: nonlinear processes generating beams with the sum or difference of the frequencies of the input beams

German: Summen- und Differenzfrequenzerzeugung

Category: nonlinear optics

How to cite the article; suggest additional literature

Crystal materials lacking inversion symmetry can exhibit a so-called χ(2) nonlinearity. In such nonlinear crystal materials, sum frequency generation (SFG) or difference frequency generation (DFG) can occur, where two pump beams generate another beam with the sum or difference of the optical frequencies of the pump beams. Such a process requires phase matching to be efficient, and usually there is no simultaneous phase matching for sum and difference frequency generation. A sum frequency mixer is sometimes called a FASOR (Frequency Addition Source of Optical Radiation).

A special case is sum frequency generation with an original pump wave and a frequency-doubled part of it, effectively leading to frequency tripling. Such a cascaded process can be much more efficient than direct frequency tripling on the basis of a χ(3) nonlinearity.

Typical Applications

Some typical applications of sum frequency generation are:

Difference frequency mixing with pump waves of similar frequency can lead to a mixing product with a long wavelength. Some examples are:

Such mid-infrared wavelengths are required, e.g., for the spectroscopy of gases.

Difference frequency generation can also be used for generating terahertz waves. For efficient terahertz wave generation, there are special semiconductor-based photomixers, where the terahertz beat note of two similar optical frequencies generates an oscillation of the carrier density in the semiconductor, which is translated into an oscillating current and then into terahertz radiation.

Insight from a Photon Picture

In a sum frequency mixer, both pump waves experience pump depletion when the signal becomes intense. For efficient conversion, the photon fluxes of both input pump waves should be similar. If one input wave has a lower photon flux, and its power is totally depleted somewhere in the crystal, there can be backconversion during subsequent propagation.

In a difference frequency mixer, the lower-frequency wave is amplified rather than depleted. This is because photons of the beam with highest photon energy (shortest wavelength) are effectively split into two lower-frequency photons, thus adding optical power to both lower-frequency waves. The term parametric amplification emphasizes the aspect of amplification, and the difference frequency mixing product is then called the idler wave.

Bibliography

[1]M. Bass et al., “Optical mixing”, Phys. Rev. Lett. 8 (1), 18 (1962)
[2]S. Guha and J. Falk, “The effects of focusing in the three-frequency parametric upconverter”, J. Appl. Phys. 51 (1), 50 (1980)

(Suggest additional literature!)

See also: frequency doubling, frequency tripling, parametric amplification, parametric nonlinearities, phase matching, mid-infrared laser sources

How do you rate this article?

Your general impression: don't know poor satisfactory good excellent
Technical quality: don't know poor satisfactory good excellent
Usefulness: don't know poor satisfactory good excellent
Readability: don't know poor satisfactory good excellent
Comments:

Found any errors? Suggestions for improvements? Do you know a better web page on this topic?

Spam protection: (enter the value of 5 + 8 in this field!)

If you want a response, you may leave your e-mail address in the comments field, or directly send an e-mail.

If you like our website, you may also want to get our newsletters!

arrow
higher-order solitons

Evolution of the spectrum of a third-order soliton pulse.

This diagram has been made with the RP ProPulse software.

– Show all banners –

– Get your own banner! –