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Notch filtering using a multiple passband AOTF in the SWIR region
Applied Optics
|November 10, 2016
Summary
This study demonstrates a novel notch filtering technique using a TeO2 acousto-optic tunable filter (AOTF) for selective laser wavelength rejection in the shortwave infrared region, enabling advanced optical filtering capabilities.
Area of Science:
- Optics and Photonics
- Materials Science
Background:
- Acousto-optic tunable filters (AOTFs) are crucial for wavelength selection in optical systems.
- Achieving precise spectral rejection, or notch filtering, remains a challenge in shortwave infrared (SWIR) applications.
Purpose of the Study:
- To implement and characterize a notch filtering operation using a TeO2 AOTF in the SWIR region.
- To investigate the see-through capability and rejection levels achievable by selectively deactivating AOTF passbands.
Main Methods:
- Utilized a TeO2 AOTF with 16 simultaneous overlapping passbands in the SWIR wavelength region.
- Employed radio frequency signal manipulation to deactivate specific passbands, thereby rejecting corresponding laser wavelengths.
- Incorporated telecentric confocal optics to mitigate AOTF-induced aberrations during imaging.
Main Results:
- Demonstrated successful notch filtering by switching off specific RF signals to the AOTF, rejecting unwanted laser wavelengths.
- Quantified rejection levels, limited by sidelobe leakage, through theoretical analysis and experimental measurements.
- Showcased a trade-off between rejection level and see-through capability when deactivating multiple passbands.
Conclusions:
- The TeO2 AOTF effectively performs notch filtering in the SWIR, offering tunable spectral rejection.
- Sidelobe leakage is a key factor influencing rejection efficiency, manageable through system design and operation.
- The developed system provides a versatile platform for advanced optical filtering and imaging in the SWIR spectrum.
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