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). Two types of devices are currently common, frequency doublers often based on lithium niobate (LN), lithium tantalate (LT), potassium titanyl phosphate (KTP) or lithium triborate (LBO), and frequency triplers typically made of potassium dihydrogen phosphate or commonly known as KDP. Both are widely used in optical experiments that use lasers as a light source.

There are two processes that are commonly used to achieve the conversion, second harmonic generation (SHG, also called frequency doubling), or sum frequency generation which sums two non-similar frequencies. Direct third harmonic generation (THG, also called frequency tripling) also exists, but known examples of these devices are very low efficiency and are generally not used in practice. "Real world" triplers use a two-stage process, combining two photons using SHG, then adding a third using summing.

Optical frequency multipliers are very common in high-power lasers, notably those used for inertial confinement fusion (ICF) experiments. ICF attempts to use a laser to heat and compress a target containing fusion fuel, and it was found in experiments with the Shiva laser that the infrared frequencies generated by the laser lost most of its energy in the hot electrons being generated early in the heating process. In order to avoid this problem much shorter wavelengths needed to be used, and experiments on the OMEGA laser and NOVETTE laser validated the use of frequency tripling KDP crystals to convert the laser light into the ultraviolet, a process that has been used on almost every laser-driven ICF experiment since then.

Open source encyclopedia content modification information:

This page was last modified on 14 March 2010 at 21:18.

Authorship and Review

Open source encyclopedia content provided here is not reviewed directly by PediaView.com. Content is authored by an open community of volunteers and is not produced by or in any way affiliated with PediaView.com.

Usage Guidelines

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Third harmonic generation", which is available in its original form here:

http://en.wikipedia.org/w/index.php?title=Third_harmonic_generation

All Wikipedia text is available under the terms of the GNU Free Documentation License. Wikipedia® itself is a registered trademark of the Wikimedia Foundation, Inc.