1：Experimental Design and Method Selection:

The MCVD process was adapted to deposit a layer of Ge doped silica on planar fused silica substrates. The doped layer was then heat-treated by a CO2 laser for high optical quality and increased damage threshold. Direct laser lithography and deep dry etching were used to shape waveguides.

2：Sample Selection and Data Sources:

Fused silica substrates were used for deposition. The refractive index and Ge concentration were measured using a refractometer and the Sellmeier Equation.

3：List of Experimental Equipment and Materials:

Quartz tube, fused silica substrates, SiCl4 and GeCl4 gases, CO2 laser, direct laser lithography equipment, deep dry etching equipment.

4：Experimental Procedures and Operational Workflow:

Deposition of Ge doped silica layer, CO2 laser heat treatment, waveguide fabrication via direct laser lithography and dry etching, optical characterization.

5：Data Analysis Methods:

Optical loss characterization using a HeNe laser setup, measurement of propagation and coupling losses.