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Source: Wikipedia
Pockels Cells: Understanding the Basics
A Pockels cell is an electro-optic device that utilizes an electro-optic crystal to modulate the phase delay of a light beam by applying an electric voltage. This modulation allows for voltage-controlled waveplate functionality, making Pockels cells essential components in electro-optic modulators, optical switches, and sensors for electric voltages.
Geometries and Materials
Pockels cells can have two main geometries based on the direction of the electric field: longitudinal and transverse. Common materials used in Pockels cells include potassium di-deuterium phosphate (KD*P = DKDP), potassium titanyl phosphate (KTP), and lithium niobate (LiNbO3).
Half-wave Voltage
The half-wave voltage is a crucial parameter for Pockels cells, representing the voltage needed to induce a phase change equivalent to half an optical wavelength. This property varies based on the crystal material, electrode separation, and electric field application length.
Modulation Bandwidth and Electric Current Requirements
Pockels cells offer high modulation bandwidth potential, limited by the speed of electric field modifications. They require minimal electric current due to the crystal’s dielectric nature, but rapid voltage changes may demand substantial currents. The modulation bandwidth can be affected by the cell’s electrical capacitance.
Details to Consider in Practical Applications
In real-world applications, factors like crystal size for high-power lasers, residual absorption, end reflectivities, temperature dependence, optical nonlinearities, and piezoelectric ringing effects need to be considered. These factors can impact the performance and efficiency of Pockels cells in various applications.
Overall, Pockels cells play a significant role in photonics technology, enabling precise control and modulation of light beams in a wide range of applications across industries.
Source: G&H photonics
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