Oct 8 2013
Optical rectification or electro-optic rectification is a non-linear optical process that generates a quasi-DC polarization in a non-linear medium by passing an intense beam of light. This phenomenon is the reverse of the electro-optic effect (the electro-optic effect is the term used to describe the changes in the optical properties of the material due to the presence of an electric field).
This phenomenon was first observed in the year 1962 in potassium dideuterium phosphate crystals when light from a ruby laser was transmitted through them.
Practical Requirements
Various non-linear materials can undergo optical rectification, such as semiconductors, inorganic, and organic electro-optic crystals.
The required light source is a pulsed laser source, more specifically, a femtosecond pulsed laser. The light from the laser is linearly polarized and made to pass through two electrodes with the non-linear optical material filling the gap between electrodes.
The result is the generation of a DC current or a radio frequency, due to polarization of the non-linear material.
Physical Principle
Optical rectification refers to the generation of a DC or a low-frequency polarization that occurs when an intense light beam transmits through a crystal. As per the linear electro-optic effect, the polarization of a crystal is changed by the application of an electric field.
In case of optical rectification, the reverse happens; a change in polarization of a non-linear optical material generates a DC current. Optical rectification can occur only in non-linear or non-centrosymmetric materials.
Applications
Some of the typical applications of optical rectification phenomenon are described below:
- Generation of radiation in the order of terahertz
- Terahertz time-domain spectroscopy.
Sources and Further Reading