Realization and optimization of planar refracting microlenses by Ag-Na ion-exchange techniques

Area of Science:

• Optics and Photonics
• Materials Science
• Glass Science

Background:

• Planar microlenses are crucial optical components for miniaturized systems.
• Achieving high numerical apertures (N.A.) in microlenses is challenging due to material limitations.
• Existing models predict a lower N.A. limit for Ag-Na ion exchange in glass.

Purpose of the Study:

• To fabricate planar microlenses with high numerical apertures (N.A.).
• To investigate the field-assisted silver-sodium (Ag-Na) ion exchange process for microlens fabrication.
• To propose and validate a new definition for measuring microlens N.A. based on diffraction-limited performance.

Main Methods:

• Fabrication of planar microlenses using field-assisted Ag-Na ion exchange in glass.
• Measurement of microlens numerical apertures (N.A.).
• Analysis and discussion of different N.A. measurement definitions, including a proposed diffraction-limited performance metric.

Main Results:

• Successfully fabricated planar microlenses with N.A. values as high as 0.2.
• Achieved N.A. values exceeding the ~0.1 limit predicted by simple index difference models.
• Demonstrated diffraction-limited performance across the entire aperture of the fabricated microlenses.

Conclusions:

• Field-assisted Ag-Na ion exchange enables the fabrication of planar microlenses with significantly enhanced N.A.
• The proposed N.A. definition based on diffraction-limited performance provides a more accurate assessment of microlens quality.
• These high-N.A. microlenses hold promise for advanced optical imaging and sensing applications.