Advanced control of an acousto-optic filter performance through arbitrary RF signals

Area of Science:

• Photonics and Optical Engineering
• Acousto-Optics
• Signal Processing

Background:

• Acousto-optic tunable filters (AOTFs) are crucial optical devices.
• Controlling AOTF transmission functions, particularly selectivity and side-lobe levels, is essential for advanced applications.
• Arbitrary waveform generators offer precise control over applied signals.

Purpose of the Study:

• To investigate the impact of tailored radio frequency (RF) signals on acousto-optic tunable filter (AOTF) performance.
• To explore the relationship between acoustic pulse characteristics and filter transmission functions.
• To validate simulation models with experimental measurements.

Main Methods:

• Utilizing an arbitrary waveform generator to create specific RF signals.
• Applying these signals to a quasicollinear acousto-optic tunable filter.
• Analyzing filter transmission functions by controlling acoustic pulse duration and shape.
• Employing fast Fourier transform (FFT) based simulations for comparison.

Main Results:

• Demonstrated ability to modify AOTF selectivity and side-lobe levels by controlling RF pulse parameters.
• Measurement results showed strong agreement with FFT-based simulation models.
• Identified the Hamming window as an effective method for suppressing side lobes.

Conclusions:

• Precise control of RF signals enables fine-tuning of AOTF performance.
• FFT-based modeling accurately predicts AOTF behavior.
• The Hamming window is a practical solution for reducing unwanted side lobes in AOTF transmission, even at high acoustic powers.