Process for the production of light microguides with low optical propagation losses by multicoating deposition

Claim 1

A process for the production of light microguides with low optical propagation losses by multilayer deposition comprising, deposited in this order on a substrate (1), a first layer (2) of index n, a second guide layer (3) of index n+Δn 1 and a third layer (5) covering the two aforementioned layers of index n+Δn 2 , with Δn 2 <Δn 1 or n-Δn 2 , characterized in that the second guide layer (3) is deposited in two successive stages involving a first deposition stage followed by a partial etching of a first intermediate layer (3a) through an appropriate mask, in order that the unmasked part of the first intermediate layer has a thickness, countered from the interface located between the first layer and the first intermediate layer equal to h and compatible with the accuracy of the etching so as not to reach the interface between the first layer (2) and the second layer (3), a second stage of depositing a second intermediate layer (3b) of a material having the same index n+Δn 1 as the first preceding intermediate layer (3a) and surmounting the same by a height h' adequate not to reproduce the etching defects of said preceding intermediate layer (3a), the total thickness h+h' of the etched part of the second layer having to be compatible with the operation of the microguide.