Functional optical devices and methods for producing them

Abstract

A functional optical device has cores which are trenches, different portions of the cores being formed from different core materials. The optical device can be formed by forming trenches 5, 7, 9 within a substrate (normally a substrate 1 covered by a cladding layer 3 ), covering at least part of at least one trench 7 with a cover 11 , depositing a first cladding layer 13 of a first cladding material to fill the trenches 5, 9 which are not covered, removing the cover 11, depositing a second cladding layer 15 of a second cladding material to fill the trenches 7 which were previously covered, removing core material outside the trenches 5, 7, 9, and applying a cladding layer to cover the trenches.

1 . An optical device comprising: 
 at least two optical paths of different geometrical lengths;    wherein light passes along the two optical paths and interacts;    wherein each of the optical paths is a trench within a cladding layer, and wherein the optical paths are separated by the cladding layer;    wherein at least one optical path comprises a first region and a second region composed of different core materials and having different refractive indices varying with temperature;    wherein the core materials in the first region and the second region are chosen such that interaction between the light passing along the paths is temperature independent.    
   
   
       2 . An optical device according to  claim 1  which is an interferometer.  
   
   
       3 . An optical device according to  claim 1  which is an arrayed-waveguide grating having a plurality of optical paths.  
   
   
       4 . An optical device according to  claim 3 , wherein each path intersects a region within which the cores comprise a different material from the cores outside the region; and the intersection of the optical paths with the region varies with the geometrical length of the optical paths.