Patent ID: 8300999

Claim:
An optical device, comprising: a light-transmitting medium positioned on a base, the light-transmitting medium at least partially defining a free propagation region through which light signals travel; and a reflective grating positioned such that light signals that travel through the free propagation region can be received by the optical grating, the optical grating being configured to reflect the light signal back into the free propagation region, the optical grating reflecting the light signals such that the light signals associated with different wavelengths separate as the light signals travel through the free propagation region, a portion of the light-transmitting medium that defines the free propagation region having a facet through which the light signals are transmitted, the grating including a reflecting layer configured to reflect the light signals received by the grating, the grating including a buffer layer between the facet and the reflecting layer such that light signals transmitted through the facet and reflected by the reflecting surface travel through the buffer layer.