Application characteristics of electro-optic modulator

The basis of an electro-optic modulator is the electro-optic effect. According to the relationship between the refractive index change of electro-optic crystals and the applied electric field strength, electro-optic effects can be divided into linear electro-optic effects (Pockels effect) and quadratic electro-optic effects (Kerr effect). Because the linear electro-optic effect is more effective than the quadratic electro-optic effect, linear electro-optic modulators are often used in practice to modulate light waves. Linear electro-optic modulators can be divided into longitudinal and transverse types. In a vertical modulator, the electric field is parallel to the direction of light propagation, while in a horizontal modulator, the electric field is perpendicular to the direction of light propagation.

An electro-optic modulator is a modulator made using the electro-optic effect of certain electro-optic crystals, such as lithium niobate crystal (LiNbO3), gallium arsenide crystal (GaAs), and lithium tantalate crystal (LiTa03). The electro-optic effect is that when a voltage is applied to an electro-optic crystal, the refractive index of the crystal changes, resulting in a change in the characteristics of the light waves passing through the crystal, which modulates the phase, amplitude, intensity, and polarization state of the optical signal

Electro optic modulators have excellent characteristics and can be used for optical links between base stations and relay stations in fiber optic cable television (CATV) systems, wireless communication systems, and other fiber optic analog systems.

Electro optic modulators have many applications. Phase modulators can be used in coherent fiber optic communication systems, as comb generators for generating multiple optical frequencies in dense wavelength division multiplexing fiber optic systems, and as electro-optic frequency shifters for laser beams.

Electro optic modulators are not only used in the aforementioned systems to generate high repetition rate, extremely narrow optical pulses or solitons, but also in advanced radar deception systems as photonic broadband microwave phase shifters and frequency shifters, in microwave phased array radar as photonic time delays, in optical wave component analyzers, and for measuring weak microwave electric fields.