1：Experimental Design and Method Selection:

A one-step base-catalyzed sol-gel process was employed to fabricate nanoporous silica coatings using tetraethoxysilane (TEOS) as the precursor and hexamethylisilazane (HMDS) as the modifier. The method is designed to be inexpensive, etchant-free, and without high temperature calcination treatment.

2：Sample Selection and Data Sources:

Fused silica substrates were used for the deposition of coatings. The coatings' properties were characterized using various techniques including UV–vis-NIR spectroscopy, SEM, TEM, FTIR, AFM, and ellipsometry.

3：List of Experimental Equipment and Materials:

TEOS, HMDS, ethanol, PDMS, and concentrated ammonia water were used. Equipment included a dip-coating device, UV–vis-NIR spectrometer, SEM, TEM, FTIR spectrometer, AFM, and spectroscopic ellipsometer.

4：Experimental Procedures and Operational Workflow:

The sols were prepared by mixing TEOS, HMDS, ethanol, and ammonia water, followed by aging. Coatings were deposited on substrates via dip-coating. The double-layer coating was fabricated by sequentially coating the bottom and top layers.

5：Data Analysis Methods:

The refractive indices and thickness of the films were measured using spectroscopic ellipsometry. Transmittance spectra were recorded, and the coatings' stability and LIDT were tested.