Method and apparatus for adding metals to fused silica

A method of fabricating a bulk aluminum-doped fused silica glass article, the method comprising the steps of:

• providing a silicon-containing gas stream capable of being converted through thermal decomposition with oxidation or flame hydrolysis to silica;
• flowing a second gas stream over a powdered, organometallic aluminum-containing precursor and sublimating the precursor to saturate the gas with the organometallic aluminum-containing precursor and to provide an aluminum dopant-containing gas stream;
• mixing the silicon-containing gas stream and the aluminum dopant-containing gas stream;
• flowing the mixed gas streams into the flame of a combustion burner to form amorphous particles of aluminum doped fused silica;
• depositing the amorphous particles onto a support;
• consolidating the deposit of amorphous particles into a transparent glass body containing between 100 parts per billion and 100 parts per million of aluminum and having an internal transmittance of greater than 99.5%/cm at a wavelength of 193 nm.