Laser processing of sapphire and fabrication of diffractive optical elements

Area of Science:

• Materials Science
• Optical Engineering
• Laser Processing

Background:

• Sapphire is a robust optical material with excellent thermal and chemical properties.
• Its optical transparency spans from 0.15 µm to 5.5 µm, suitable for infrared applications.
• Advanced fabrication techniques are needed to create micro/nanostructures on sapphire for optical devices.

Purpose of the Study:

• To investigate the laser processing of sapphire using a nanosecond pulsed laser.
• To fabricate diffraction gratings and photon sieves for infrared spectrum applications.
• To characterize the fabricated microstructures and their optical performance.

Main Methods:

• Utilized a 355 nm wavelength nanosecond pulsed laser for sapphire ablation.
• Fabricated diffraction gratings and photon sieve structures.
• Analyzed laser removal rates and surface roughness.
• Characterized diffracted beam profiles, optical diffraction efficiency, surface morphology, and depth profiles.

Main Results:

• Demonstrated successful laser fabrication of diffraction gratings and photon sieves on sapphire.
• Quantified laser removal rates and surface roughness as a function of processing parameters.
• Evaluated the optical performance, including diffraction efficiency and beam profiles.
• Detailed surface morphology and depth profiles of the fabricated microstructures.

Conclusions:

• Laser processing is a viable method for fabricating micro/nanostructures on sapphire for infrared applications.
• The study provides critical data on laser-material interactions for sapphire.
• Fabricated gratings and photon sieves show potential for use in infrared optical systems.