OPTOELECTRONIC DEVICE AND ARRAY THEREOF

1 . A photonic chip, comprising:

a waveguide; and

an optically active device comprising a portion of the waveguide,

the waveguide having:

a first end at a first edge of the photonic chip; and

a second end, and

the waveguide having, everywhere between the first end and the second end, a rate of change of curvature having a magnitude not exceeding 2,000/mm 2 .

2 . The photonic chip of claim 1 , wherein the area of a rectangle containing the waveguide is less than 1000 square microns.

3 . The photonic chip of claim 1 , wherein the length of a rectangle containing the waveguide is less than 200 microns.

4 . The photonic chip of claim 1 , wherein the width of a rectangle containing the waveguide is less than 80 microns.

5 . The photonic chip of claim 1 , wherein the waveguide includes a first tapered portion, having a wide end nearer the first end, and a narrow end nearer the second end.

6 . The photonic chip of claim 5 , wherein the wide end is within 10 microns of the first end.

7 . The photonic chip of claim 6 , wherein the length of the first tapered portion is within 30% of one third of the length of the waveguide.

8 . The photonic chip of claim 7 , wherein the waveguide has a first width at the wide end and a second width at the narrow end, and the first tapered portion has a length of at least 8 times the difference between the first width and the second width.

9 . The photonic chip of claim 8 , wherein the curvature of the waveguide at the first end is less than 0.1/mm.

10 . The photonic chip of claim 9 , wherein the curvature of the waveguide at the second end is less than 0.1/mm.

11 . The photonic chip of claim 10 , wherein the curvature at a point in the middle 80% of the waveguide is less than 0.1/mm.

12 . The photonic chip of claim 1 , wherein the waveguide is, at every point along the waveguide, within 3 microns of an adiabatic curve.

13 . The photonic chip of claim 1 , wherein the greatest value of the magnitude of the rate of change of curvature of the waveguide is within 40% of the average value of the magnitude of the rate of change of curvature of the waveguide.

14 . The photonic chip of claim 1 , wherein the waveguide is, at every point along the waveguide, within 3 microns of a Bezier spline.

15 . The photonic chip of claim 1 , wherein the waveguide has, at a first point along its length, an asymmetric profile.

16 . The photonic chip of claim 15 , wherein at the first point, the waveguide has a first sidewall having a first height and a second sidewall having a second height, the second height being at least 30% greater than the first height.

17 . The photonic chip of claim 1 , wherein:

the second end is at the first edge of the photonic chip;

the waveguide has a first facet at the first end, and a second facet at the second end;

the first facet is:

oblique to the waveguide at the first end, and

oblique to the first edge,

a fundamental mode of the waveguide at the first end corresponds to a first free space beam outside the first facet, the first free space beam having a first centerline;

a fundamental mode of the waveguide at the second end corresponds to a second free space beam outside the second facet, the second free space beam having a second centerline; and

the first centerline is within 10 degrees of being parallel to the second centerline.

18 . The photonic chip of claim 17 , wherein the second centerline is within 10 degrees of a direction that is the mirror image of the direction of the first centerline.

19 . The photonic chip of claim 18 , wherein:

the first centerline is within 10 degrees of being perpendicular to the first edge, and

the second centerline is within 10 degrees of being perpendicular to the first edge.

20 . The photonic chip of claim 1 , wherein the total direction change within the waveguide is less than 175 degrees.

21 . The photonic chip of claim 20 , wherein the total direction change within the waveguide is less than 155 degrees.