Electro-Optic Modulators

Thorlabs’ free-space electro-optic (EO) amplitude and phase lithium
niobate modulators combine crystal growth and electro-optic materials.
Our standard modulators use undoped lithium niobate. For higher-power
operation, we offer MgO-doped lithium niobate. The standard EO
modulators are broadband DC-coupled, and a high Q resonant model
option is available.

Our standard DC-coupled broadband EO modulators consist of an EO
crystal packaged in a housing optimized for maximum RF performance.
The RF drive signal is connected directly to the EO crystal via the SMA
RF input. An external RF driver supplies the drive voltage for the desired
modulation. The crystal may be modulated from DC up to the frequency
limits of the external RF driver.

For flexibility, Thorlabs also offers a second modulator option. Resonant
frequency modulators simplify the driver requirements for many
applications where the modulator is operated at a single frequency. A high
Q resonant tank circuit located inside the modulator boosts the low-level
RF input voltage from a standard function generator to the high voltage
needed to get full depth of modulation. Call our tech support team for
details on the specific resonant frequencies available.
EO Amplitude Modulators

The electro-optic amplitude modulator (EO-AM) is a Pockels cell type modulator consisting of two matched lithium niobate crystals (see figure 2 on the Graph Tab) packaged in a compact housing with an RF input connector. Applying an electric field to the crystal induces a change in the indices of refraction (both ordinary and extraordinary) giving rise to an electric field dependent birefringence which leads to a change in the polarization state of the optical beam. The EO crystal acts as a variable waveplate with retardance linearly dependent on the applied electric field. By placing a linear polarizer at the exit, the beam intensity through the polarizer varies sinusoidally with linear change in applied voltage.

EO-Phase Modulator Specifications
Specification Description
Modulator Crystal Lithium Niobate (LiNbO3)
Wavelength Range
C1 600nm to 900nm
C2 900nm to 1250nm
C3 1250nm to 1650nm
C4 400nm to 600nm
Clear Aperture Ø2mm
Input Connector SMA Female
Half Wave Voltage, V
240V@1064nm
Max Optical Power Density 2W/mm2 @ 532nm, 4W/mm2 @ 1064nm
Capacitance 14pF (typical)

Features
High Performance in a Compact Package
Broadband DC Coupled
2 mm Diameter Clear Aperture
SMA RF Modulation Input Connector
DC to 100 MHz
Custom OEM Versions Available
Standard DC-Coupled Broadband Modulators
Our broadband EO modulators consist of an EO crystal packaged in a housing optimized for maximum RF performance. The RF drive signal is connected directly to the EO crystal via the SMA RF input. An external RF driver supplies the drive voltage for the desired modulation. The crystal may be modulated from DC up to the frequency limits of the external RF driver. Please see the Specs tab for amplifier requirements.

High Q Resonant Option
For flexibility Thorlabs also offers a second modulator option. Resonant mode modulators developed by Nova Phase simplify the driver requirements for many applications where the modulator is operated at a single frequency. A high Q resonant tank circuit located inside the modulator boosts the low level RF input voltage from a standard function generator to the high voltage needed to get full depth of modulation.