Preparation Of GeO₂Hollow Waveguide And Property Investigations

The features and applications of hollow optical waveguide are introduced in thisthesis. The GeO₂ceramic film was grown on the inner wall of a silica glass tubeusing an acid-induced liquid phase deposition （acid-induced LPD） method. Theinterreaction between GeO₂and OH-can produce soluble germanate ions. Thesolubility of GeO₂in an alkaline aqueous solution can be increased. By designedlyadding acid into the aqueous germanate ion solution, GeO₂solid phases cangradually precipitate out of the solution. GeO₂ceramic films may be graduallyformed inside a silica glass tube filled with aqueous acidic germanate ion solution. Acompact GeO₂reflective film is produced by sintering the ceramic film at atemperature around the melting point of GeO₂（1115℃）. The phase structures,morphologies, thicknesses and optical transmission properties of the GeO₂hollowsamples were studied. Optimal preparation conditions are obtained based on fullinvesitiguations of the fabrication parameters （concentration and pH of the precursorsolution, deposition times, heat treatment temperature and time, etc）, crystal phasestructures, morphologies, thicknesses and optical transmission properties of theGeO₂hollow samples.The results show that the GeO₂hollow waveguides fabricated using theGeO₂-ammonia precursor solution exhibit transmission loss values within0.19-2.44dB/m. The transmission loss decreases as the concentration of the aqueousgermanate ion solution increases from5%to7%. The loss of the sample depositedfrom the8-9%GeO₂solution is higher than that of the sample deposited from the7%solution. The sample deposited from the9%solution has a lower loss than thesample deposited from the8%solution. The loss firstly decreases and then goes upwith the increase of the deposition time, deposition cycle and pH. The transmissionloss does not change greatly as the pH of the precursor solution varies from1to3.When nitric acid, sulfuric acid and phosphate acid were used to acidize the precursorsolution, the waveguide sample deposited from the nitric acid induced solution hasmaximum transmission loss while the sample deposited from the phosphate acid induced solution shows the minmum loss. The transmission loss decays as thesintering temperature increases from1110℃to1130℃, and the sample sintering at1140℃or1150℃exhibits a higher loss. The transmission loss decreases and thenincreases with prolongation of the sintering time. The loss of the sample naturallycooled to room temperature is lower than the sample taken out of the oven at a hightemperature. The GeO₂hollow waveguides deposited from the GeO₂-NaOHprecursor solutions have losses from0.18dB/m to2.70dB/m. The transmission lossreduces as concentration of the precursor solution increases from9%to11%. Theloss firstly increases and then decreases with increasing deposition time. The lossgoes up as pH and deposition cycle increase. The effects of sintering temperature,cooling operations as well as acid sort on the loss are the same to what have beenobserved in the investigation of samples deposited from the aqueous ammonia-GeO₂solutions. The transmission loss firstly goes down and then increases as the sinteringtime goes up.