Optical component having features extending different depths into a light transmitting medium
View Patent ↗The optical device includes a plurality of waveguides and an optical grating. A first portion of the waveguides act as input waveguide configured to carry a light beam that includes multiple light signals to the optical grating. The optical grating is configured to demultiplex the light signals. A second portion of the waveguides act as output waveguides configured to carry the demultiplexed light signals away from the optical grating. A method of forming the optical device includes sequentially forming the waveguides and the optical grating while a single mask defines the location of the waveguides and the optical grating.
1. A method of forming an optical device, comprising:
forming a first mask on a device precursor having a light-transmitting medium positioned on a base,
the first mask protecting a free space region of the device precursor while leaving exposed a grating recess region of the device precursor and leaving exposed trench regions of the device precursor,
the grating recess region being a region of the light-transmitting medium where a grating recess is to be formed,
the trench regions being regions of the light-transmitting medium where trenches are to be formed,
the free space region spanning a gap between the trench regions and the grating recess region;
forming the trenches while protecting the grating recess region or while protecting the grating recess, the trenches each including one or more waveguide surfaces, each waveguide surface defining a portion of one or more waveguides on the optical device;
forming the grating recess while protecting the trench regions or while protecting the trenches, the grating recess including a reflective surface of an optical grating,
the reflective surface configured to receive light signals from one or more of the waveguides and to reflect the received light signals such that the light signals are demultiplexed as the light signals travel away from the reflective surface,
a portion of the waveguides configured to receive the demultiplexed light signals,
the waveguide surfaces extending a different depth into the light-transmitting medium than the reflective surface extends into the light-transmitting medium; and
wherein the first mask is present on the device while forming the grating recess and also while forming the trench regions.
2. The method of claim 1 , wherein forming the grating recess includes etching the light-transmitting medium and forming the trenches includes etching the light-transmitting medium.
3. The method of claim 1 , wherein forming the grating recess while protecting the trench regions or while protecting the trenches includes forming a second mask on the device precursor,
at least a portion of the second mask being formed over the first mask, and
the second mask protecting the trench regions or the trenches.
4. The method of claim 1 , wherein the optical grating is an echelle grating.
5. The method of claim 1 , wherein forming the trenches while protecting the grating recess region or while protecting the grating recess includes forming a second mask on the device precursor,
at least a portion of the second mask being formed over the first mask, and
the second mask protecting the grating recess region or protecting the grating recess.
6. The method of claim 5 , wherein the second mask includes a metal or a polyimide.
7. The method of claim 1 , wherein
forming the trenches while protecting the grating recess region or while protecting the grating recess includes forming a second mask on the device precursor,
at least a portion of the second mask being formed over the first mask, and
the second mask protecting the grating recess region or protecting the grating recess; and
forming the grating recess while protecting the trench regions or while protecting the trenches includes forming a third mask on the device precursor,
at least a portion of the third mask being formed over the first mask, and
the third mask protecting the trench regions or the trenches.
8. The method of claim 7 , wherein the third mask includes a metal or a polyimide.
9. The method of claim 7 , further comprising, removing the second mask before forming the third mask.
10. The method of claim 7 , further comprising, removing the third mask before forming the second mask.
11. The method of claim 7 , wherein forming the grating recess includes etching the grating recess into the light-transmitting medium and forming the trenches includes etching the trenches into the light-transmitting medium.
12. The method of claim 7 , wherein the third mask includes a hard mask.
13. The method of claim 12 , wherein the third mask includes a layer of silica over a layer of nitride.
14. The method of claim 13 , wherein the edges of silica layer are aligned with the edges of the nitride layer.
15. The method of claim 13 , wherein forming the third mask includes performing a wet etch of the nitride layer, the wet etch being selective for the nitride layer over the silica layer.