High-precision high-stability acousto-optic pulse picking driver with a direct digital synthesis technique.

Area of Science:

• Laser physics
• Optical engineering
• Signal processing

Background:

• Mode-locked lasers produce pulsed outputs critical for many applications.
• Acousto-optic modulators (AOMs) are used for pulse picking but require precise signal synchronization.
• Amplitude fluctuations in AOM output can limit subsequent laser amplification efficiency.

Purpose of the Study:

• To develop a method for maintaining a fixed phase relationship between an AOM's driving signal and a mode-locked seed laser.
• To stabilize the amplitude of the diffracted signal output from the AOM.
• To create a flexible pulse-picking solution for laser amplification.

Main Methods:

• Utilizing a field-programmable gate array (FPGA) and summing amplifiers to synthesize synchronized driving signals.
• Achieving high-timing precision synchronization with an accuracy of 160 ps.
• Implementing a control system for flexible adjustment of driving signal frequency and gating width.

Main Results:

• Significantly reduced the standard deviation of the AOM's diffracted signal output from 0.52% to 0.18%.
• Demonstrated stabilized amplitude of the diffracted signal.
• Validated the effectiveness of the FPGA-based synchronization method.

Conclusions:

• The proposed method effectively stabilizes AOM output amplitude by precisely controlling the driving signal phase.
• This technique enhances convenience and suitability for various mode-locked lasers in subsequent amplification stages.
• The developed pulse-picking solution offers improved performance and flexibility for laser systems.