Concave silicon micromirrors for stable hemispherical optical microcavities.

Area of Science:

• Optics and Photonics
• Materials Science
• Microfabrication

Background:

• Hemispherical microcavities are crucial for applications requiring high frequency stability.
• Fabrication of silicon concave micromirrors presents challenges in achieving desired depth, roughness, and aspect ratios.
• Previous methods limited achievable cavity depths, impacting performance.

Purpose of the Study:

• To present a detailed study on the fabrication of silicon concave micromirrors for hemispherical microcavities.
• To investigate key fabrication parameters including yield, surface quality, roughness, cavity depth, radius of curvature, and aspect ratio.
• To demonstrate the possibility of achieving larger cavity depths than previously reported.

Main Methods:

• Detailed fabrication process for silicon concave micromirrors.
• Characterization of surface quality, roughness, cavity depth, and radius of curvature.
• Analysis of aspect ratio (cavity depth to radius of curvature).
• Assembly of hemispherical microcavities using fabricated micromirrors.

Main Results:

• Achieved significantly larger cavity depths compared to prior reports.
• Maintained desirable aspect ratios and nanometer-level surface roughness.
• Demonstrated high finesse (F = 1524) and quality factor (Q = 3.78 x 10^5) in assembled microcavities.
• Improved insensitivity to fabrication variations for mode coupling optics.

Conclusions:

• The presented fabrication method enables larger cavity depths for silicon concave micromirrors.
• These micromirrors lead to enhanced frequency stability and robustness in hemispherical microcavities.
• The achieved high finesse and quality factor validate the performance of the fabricated micromirrors.