Laser output power stabilization for direct laser writing system by using an acousto-optic modulator

Area of Science:

• Optics and Photonics
• Laser Technology
• Optical Engineering

Background:

• Laser output power instability in direct laser writing systems causes resolution fluctuations.
• Fabrication of diffractive optical elements and computer-generated holograms requires stable laser power.
• Existing laser systems may suffer from power fluctuations affecting precision applications.

Purpose of the Study:

• To stabilize the output power of an Argon-ion (Ar(+)) laser for a direct laser writing system (LWS).
• To investigate the effectiveness of a feedback control system in reducing laser power fluctuations.
• To demonstrate the applicability of the developed stabilization system to other laser types, such as He-Ne lasers.

Main Methods:

• Implemented a feedback loop incorporating an acousto-optic modulator, a photodetector, and a servo controller.
• Utilized an Ar(+) laser as the primary light source for the direct laser writing system.
• Tested the system's performance over extended periods and applied it to a 2 mW internal mirror He-Ne laser.

Main Results:

• Achieved output power stability of +/-0.20% for 12 minutes with the Ar(+) laser.
• Attained a relative intensity noise level of 2.1 x 10(-7) Hz(-12) at 100 Hz.
• Demonstrated improved output power stability of +/-0.12% for 25 minutes with a He-Ne laser.

Conclusions:

• The developed feedback system effectively stabilizes laser output power for direct laser writing applications.
• The power stabilization technique enhances the resolution and quality of fabricated diffractive optical elements and computer-generated holograms.
• The system is adaptable and successful in stabilizing power for different laser types, broadening its potential use.