Emitter array
In an optical emitter device, when point emitters are placed on the focal plane of a lens system, each individual point emitter will point to a specific free space angle depending on the position of the point emitter relative to the longitudinal central axis of the lens system. The plurality of point emitters are arranged in an array comprising a plurality of rows of point emitters and a plurality of columns of point emitters. Each of the plurality of point emitters comprises a grating coupler configured to emit a respective beam of light in a respective transmission direction. Each grating coupler comprises a first plurality of periodically spaced optical waveguide grating structures, at least some of the optical waveguide grating structures including a notch, whereby a first portion of each optical waveguide grating structure extends a different height than a second portion.
1 . An optical emitter device comprising:
a plurality of point emitters arranged in an array comprising a plurality of rows of point emitters and a plurality of columns of point emitters, each of the plurality of point emitters comprising:
a grating coupler configured to receive light along a transmission direction and to emit a respective beam of light in an emission direction;
each grating coupler comprising:
a first plurality of periodically spaced optical waveguide grating structures forming a directional grating for asymmetrically emitting light in the emission direction, at least some of the first plurality of periodically spaced optical waveguide grating structures including a notch, whereby a first portion of each of the first plurality of periodically spaced optical waveguide grating structures extends a different height than a second portion; and
a second plurality of periodically spaced optical waveguide grating structures superposed over the first plurality of periodically spaced optical waveguide grating structures, the second plurality of periodically spaced optical waveguide grating structures spaced apart from the directional grating in the emission direction.
2 . The optical emitter device according to claim 1 , wherein the second plurality of periodically spaced optical waveguide grating structures are laterally offset from the first plurality of periodically spaced optical waveguide grating structures.
3 . The optical emitter device according to claim 2 , wherein the second plurality of periodically spaced optical waveguide grating structures are laterally offset from the first plurality of periodically spaced optical waveguide grating structures by between 0.1 μm to 0.5 μm.
4 . The optical emitter device according to claim 1 , wherein the second plurality of periodically spaced optical waveguide grating structures are comprised of a different material than the first plurality of periodically spaced optical waveguide grating structures.
5 . The optical emitter device according to claim 1 , wherein the second plurality of periodically spaced optical waveguide grating structures are comprised of a different material with a lower index of refraction than the first plurality of periodically spaced optical waveguide grating structures.
6 . The optical emitter device according to claim 5 , wherein the second plurality of periodically spaced optical waveguide grating structures are comprised of silicon nitride; and the first plurality of periodically spaced optical waveguide grating structures are comprised of silicon.
7 . The optical emitter device according to claim 1 , wherein the second plurality of periodically spaced optical waveguide grating structures are 0.05 μm to 0.5 μm thick.
8 . The optical emitter device according to claim 1 , wherein the second plurality of periodically spaced optical waveguide grating structures are separated from the first plurality of periodically spaced optical waveguide grating structures by between 0 to 0.2 μm.
9 . The optical emitter device according to claim 1 , wherein each grating coupler is 2 μm to 5 μm in length, and 2 μm to 5 μm in width.
10 . The optical emitter device according to claim 1 , wherein the second portion only extends 40% to 60% a height of the first portion.
11 . The optical emitter device according to claim 1 , wherein a pitch and a depth of each grating coupler is configured such that the emission direction is substantially perpendicular to the transmission direction.
12 . The optical emitter device according to claim 1 , wherein each grating coupler is 5 μm to 20 μm in length, and 5 μm to 20 μm in width.
13 . The optical emitter device according to claim 1 , wherein each grating coupler is 2 μm to 5 μm in length, and 2 μm to 5 μm in width.
14 . The optical emitter device according to claim 1 , wherein the first plurality of periodically spaced optical waveguide grating structures includes a grating period of 0.5 μm to 1 μm.
15 . The optical emitter device according to claim 1 , wherein each grating coupler includes an expanding optical waveguide section extending to a respective one of the first plurality of periodically spaced optical waveguide grating structures.
16 . The optical emitter device according to claim 1 , further comprising:
a main substrate for supporting the plurality of point emitters; and
an optical waveguide structure, comprising:
a plurality of optical waveguide cores, each one of the plurality of optical waveguide cores extending to a corresponding one of the plurality of point emitters with an expanding optical waveguide section therebetween; and
cladding surrounding the plurality of optical waveguide cores.
17 . The optical emitter device according to claim 1 , further comprising a lens system, including a focal length and an optical axis, configured for redirecting the respective beams of light at a respective beam angle dependent upon a position of a respective one of the plurality of point emitters relative to the optical axis.
18 . The optical emitter device according to claim 1 , further comprising:
at least one light source for generating the light; and
a switching matrix for selectively directing at least a portion of the light to one of the plurality of point emitters.
19 . The optical emitter device according to claim 18 , further comprising at least one photodetector for detecting incoming beams of light received by the plurality of point emitters.