Patent ID: 8021561

Claim:
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.