Method for preparing core film of planar optical waveguide device

Abstract

The invention provides a method for preparing a core film of a planar optical waveguide device. The method comprises the steps that the core film is formed by silane, nitrous oxide and germane gas in a deposition mode; under a certain temperature, annealing treatment is carried out on the core film. When the gas flow of the silane is smaller than 175 sccm, the gas flow of the nitrous oxide is smaller than 3000 sccm, and the gas flow of the germane gas ranges from 12 sccm to 30 sccm, and the difference between the relative index of refraction of the prepared core film and the relative index of refraction of a coating film ranges from 0.75% to 1.5%. According to the method, the proportion of germane gas in the mixed gas is increased by reducing the gas flow of the silane and the gas flow of the nitrous oxide, the limiting effect caused by a mass flow controller on the flow of the germane gas is avoided, and thus the germanium-doped silicon dioxide core film with a high refractive index and low stress is obtained without increasing the number of mass flow controllers.

Description

technical field [0001] The invention relates to the technical field of optical fiber communication, in particular to a method for preparing a core film of a planar optical waveguide device. Background technique [0002] The planar optical waveguide type thermo-optic tunable optical attenuator based on silicon substrate, because of its advantages of simple fabrication, good stability, small size, high yield, low cost and easy integration, will surely become the first choice for optical fiber communication systems. important components. [0003] Planar optical waveguide type thermo-optic tunable optical attenuator, such as figure 1 As shown, it generally consists of a substrate 1 , a lower cladding layer 2 , a core layer 3 and an upper cladding layer 4 . In order to make the refractive index of the formed core layer higher than that of the cladding layer, in the process of preparing the core layer film, germanium atoms are introduced into the pure silicon dioxide structure t...

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Problems solved by technology

However, since the mass flow controller (Mass Flow Controller, mass flow controller) in the PECVD equipment will limit the gas flow rate of germane within a certain range, it is impossible to continue to improve the flow rate of germane by continuously increasing the flow rate of germane. The refractive index of the core film

At present, most of the methods of adding a mass flow controller to the equipment are used to increase the gas flow rate of germane. However, adding a mass flow controller needs to increase the gas path branch of the equipment, and the increase of the gas path branch will inevitably lead to The increase of hardware cost and the emergence of problems such as the increase of suspected gas leakage points

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