Acousto-Optic Frequency Shifters
Acousto-optic frequency shifters shift the frequency of input light equal to the RF drive frequency.
Our AO frequency shifters are available as standard with frequency shifts of over 300 MHz as an integrated low-power module where the RF driver has been built into the housing, or as a custom device that can achieve frequency shifts up to 600 MHz.
We fabricate our AO frequency shifters using high-quality tellurium dioxide (TeO₂), grown and polished in-house, for the lowest insertion loss and excellent power handling.
AO frequency shifters: achieving high extinction ratios
For frequency shifting with an AOFS product, the anisotropic interaction of the slow shear mode in TeO2 generates the frequency shift. Therefore, the unshifted input beam is polarized orthogonally to the diffracted, frequency-shifted beam.
A polarizer can then be used externally to the AOFS to achieve a high extinction ratio between the diffracted and un-diffracted beams. This is useful to eliminate light leakage and avoid beat patterns between the two beams. It is important to note that the achievable extinction ratio (ER) is a function of the polarizer used, and not the AOFS.
Integrated drivers and driver design
AO frequency shifters are highly efficient acousto-optic devices, requiring very low drive power to achieve the desired frequency shift. Our acousto-optic frequency shifter designs typically use the slow shear mode, resulting in slow rise time, but requiring minimal power consumption (typically < 100 mW power draw). This allows us to often package the driver with the AOFS for a compact and power-efficient solution.
In applications where power consumption is an issue, we can advise on how to best balance performance and RF drive power. Why not contact us to discuss your requirements?
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