Electro-optic Effect
Author: the photonics expert Dr. Rüdiger Paschotta (RP)
Definition: the phenomenon that the refractive index of a material can be modified with an electric field
Alternative term: Pockels effect
Categories:
DOI: 10.61835/14x Cite the article: BibTex plain textHTML Link to this page LinkedIn
The electro-optic effect (or electrooptic effect) is the modification of the optical phase delay (often described with its refractive index) of a medium, caused by an electric field. Some authors more generally consider electro-optic effects such that any optical properties may be affected by an electric field – for example, it may also be a change in absorption characteristics, such as through the Franz–Keldysh effect as used in electroabsorption modulators. In this article, only phase effects.
Only non-centrosymmetric materials (mostly nonlinear crystal materials) exhibit the linear electro-optic effect, also called the Pockels effect, where the refractive index change is proportional to the electric field strength (see the article on Pockels effect for more details).
Only materials exhibiting the Pockels effect are called electro-optic materials. Some examples of such materials are lithium niobate (LiNbO3), lithium tantalate (LiTaO3), potassium titanyl phosphate (KTP) and β-barium borate (BBO).
All centrosymmetric media exhibit only the Kerr electro-optic effect, also called Kerr effect, where the refractive index change is proportional to the square of the electric field strength, and is typically much weaker than for the linear effect within the range of electric field strength which the material can tolerate. However, there are special cases where a giant quadratic electro-optic effect is observed [1].
Most devices in electro-optics are based on the linear electro-optic effect. It is exploited in Pockels cells, which can be part of electro-optic modulators, and for electro-optic sampling.
More to Learn
Encyclopedia articles:
Bibliography
[1] | M. M. Jahanbakhshian et al., “Giant electro-optic coefficient in a graphene oxide film”, Opt. Lett. 47 (11), 2798 (2022); https://doi.org/10.1364/OL.451503 |
(Suggest additional literature!)
Suppliers
The RP Photonics Buyer's Guide contains 47 suppliers for electro-optic modulators. Among them:
Exail

Exail (formerly iXblue) offers the most comprehensive range of commercial electro-optic LiNbO3 modulators:
- the MXER-LN series of intensity modulators for the C and O bands
- the MPZ-LN phase modulators for the C and O bands
- the near-infrared phase modulators NIR-MPX for the region around 1064 nm
- the NIR-MX Mach–Zehnder modulator for the 1-μm spectral region
- the xx-MPX-LN-0.1 series for wavelengths between 780 nm and 2000 nm and low modulation frequencies
- the MZ-LN family for 1310 nm to 1550 nm with a modulation bandwidth up to 70 GHz
- the space-qualified FM-MX and FM-MPX series
- the PSW-LN and PSC-LN polarization switches and scramblers
In addition, we offer suitable bias controllers, analog and digital drivers. We also have pulse drivers for generating and shaping pulses.
See our comprehensive brochure on modulators.
EKSMA OPTICS

EKSMA Optics produces KTP, KD*P and BBO Pockels cells for applications like Q-switching of lasers, pulse picking, laser cavity dumping and coupling laser pulses into and from regenerative amplifiers. Our Pockels cells can be supplied with mounting stages, drivers, power supplies and electronics for pulse picking.
Laserton

Laserton offers electro-optic Q switches based on KTP Pockels cells with a thermally compensated double crystal design. Our improved hydrothermal-grown KTP crystals overcome the common electrochromism damage problem of flux-grown KTP.
Thorlabs

With the introduction of the OM6N series of high-speed optical modulators, Thorlabs has designed and manufactured a new all-reflective technology based on deformable mirrors for modulating laser power in the 700 – 1350 nm range. This Pockels cell or AOM alternative introduces nearly zero dispersion to ultrafast laser pulses. This solution extends Thorlabs’ existing collection of adaptive optics and EO modulators.
GWU-Lasertechnik

GWU's portfolio of electro-optical devices can meet even demanding requirements. The BBO or KD*P Pockels cells offer a high extinction ratio, fast switching capability and a high damage threshold. They can be configured in flexible design, either free-space or fiber-coupled. We also offer driver electronics.
Raicol Crystals

Raicol Crystals offers electro-optic modulators based on RTP (with a temperature compensating design) or BBO.
Besides, we can supply super-polished LBO crystals which can be used as the center piece of an electro-optic modulator. With its high resistance to laser-induced damage, LBO is very suitable for high-power applications, and its transparency range is large (160 nm – 2600 nm). We offer highly homogeneous crystals with up to 100 × 100 mm2 and very low bulk absorption.
Shalom EO

Hangzhou Shalom EO offers Pockels cells and based on DKDP, BBO, LiNbO3 and MgO:LiNbO3 crystals. Shalom EO’s Pockels cells, available in stock and custom versions, deliver the competitive edges of excellent optical transmission at your wavelengths of interest, low half-wave voltage, high damage threshold, and low insertion loss for ideal applications like pulse picking and laser cavity dumping. Various standard and custom extinction ratios are available.
In addition, Shalom EO also provides off-the-shelf and custom electro-optic crystals for EO modulation. The crystals feature rich dimension/orientation options, and large apertures, while also boasting high-precision polishing and different kinds of coatings, Cr–Au electrodes can be deposited. Various substrate materials are available: DKDP, BBO, LiNbO3, MgO:LiNbO3, TeO2, and HGTR-KTP crystals. EO modulation crystals could be offered in the forms of crystal boules, crystal blanks, and crystals with AR coatings and electrodes.
ALPHALAS

Electro-optic crystals like LiNbO3, LiTaO3, DKDP, BBO, KTP and RTP crystals in conjunction with HF drivers are available for phase or amplitude modulation. ALPHALAS has a large stock of Pockels cells and phase modulators for most of the standard laser wavelengths.
Share this with your network:
Follow our specific LinkedIn pages for more insights and updates: