Light sources with chip-level integrated diffusers
An embodiment includes a light source. The light source may include a substrate and a diffuser. The substrate may include a first surface and a second surface. The second surface may be opposite the first surface. The diffuser may be carried by the substrate. The diffuser may be configured to receive an optical signal from the substrate after the optical signal propagates through the substrate and to control a particular profile of a resultant beam of the optical signal over two axes after the optical signal propagates through the integrated diffuser.
1. A light source, comprising:
a substrate having first surface and a second surface opposite the first surface;
an optical element, positioned at the first surface of the substrate, configured to transmit an optical signal through the substrate; and
a diffuser, positioned at the second surface of the substrate, comprising a plurality of lenslets having a pseudorandom distribution of two or more focal lengths.
2. The light source of claim 1 , wherein one or more of the lenslets are positioned directly on the second surface of the substrate.
3. The light source of claim 1 , wherein one or more of the lenslets are formed in a polymer coupled to the second surface of the substrate.
4. The light source of claim 1 , wherein one or more of the lenslets are etched directly into the second surface of the substrate.
5. The light source of claim 1 , wherein at least some of the lenslets are positioned at pseudorandom locations on the second surface.
6. The light source of claim 1 , wherein at least one of the lenslets is refractive and at least one of the lenslets is diffractive.
7. The light source of claim 1 , wherein the plurality of lenslets comprise:
first portions positioned on the second surface; and
second portions positioned on the first portions.
8. The light source of claim 7 , wherein the first portions of the plurality of lenslets are etched directly into the second surface of the substrate.
9. The light source of claim 7 , wherein the second portions of the plurality of lenslets comprise a polymer overlay positioned over the first portions of the plurality of lenslets.
10. The light source of claim 7 , wherein:
the first portions of the plurality of lenslets have a first refractive index; and
the second portions of the plurality of lenslets of the plurality of lenslets that is different than the first refractive index.
11. The light source of claim 10 , wherein:
the substrate has the first refractive index; and
the first portions of the plurality of lenslets are etched directly into the second surface of the substrate.
12. The light source of claim 7 , wherein:
the first portions have a first shape configured to provide diffusion in a first direction; and
the second portions have a second shape configured to provide diffusion in a second direction that is different than the first direction.
13. The light source of claim 12 , wherein the first direction is orthogonal to the second direction.
14. The light source of claim 1 , wherein the optical element is formed in an epitaxy layer positioned on the first surface of the substrate.
15. The light source of claim 1 , wherein the optical element comprises a backside emitting optical source or a substrate-emitting vertical-cavity surface-emitting laser (VCSEL).
16. The light source of claim 1 , wherein the optical element comprises an array of substrate-emitting VCSELs.
17. The light source of claim 16 , wherein the array of substrate-emitting VCSELs are arranged in a repetitive pattern that is symmetric about at least one axis.
18. The light source of claim 16 , wherein the array of substrate-emitting VCSELs are arranged in a non-repeating and/or non-symmetric pattern.
19. A method, comprising:
transmitting an optical signal from an optical element positioned at a first surface of a substrate;
passing the optical signal through the substrate toward a second surface of the substrate opposite to the first surface;
propagating the optical signal through a diffuser positioned at the second surface of the substrate, the diffuser comprising a plurality of lenslets having a pseudorandom distribution of two or more focal lengths; and
diffracting or refracting the optical signal after the optical signal passes through the substrate, by the plurality of lenslets, to control a particular profile of a resultant beam of the optical signal.
20. A method of forming a light source, the method comprising:
forming an optical element at a first surface of a substrate, the optical element being configured to transmit an optical signal through the substrate; and
forming a diffuser at a second surface of the substrate opposite the first surface of the substrate by arranging a plurality of lenslets having a pseudorandom distribution of two or more focal lengths.
21. The method of claim 20 , wherein arranging the plurality of lenslets having the pseudorandom distribution of the two or more focal lengths comprises:
pseudorandomly selecting a location of each of the plurality of lenslets; and
forming each of the plurality of lenslets in the pseudorandomly selected locations.
22. The method of claim 20 , wherein arranging the plurality of lenslets having the pseudorandom distribution of the two or more focal lengths comprises:
pseudorandomly selecting a focal length of each of the plurality of lenslets; and
forming each of the plurality of lenslets having the pseudorandomly selected focal lengths.
23. The method of claim 20 , wherein arranging the plurality of lenslets having the pseudorandom distribution of the two or more focal lengths comprises either:
pseudorandomly selecting a location of each of the plurality of lenslets and forming each of the plurality of lenslets in the pseudorandomly selected locations; and/or
pseudorandomly selecting a focal length of each of the plurality of lenslets and forming each of the plurality of lenslets having the pseudorandomly selected focal lengths.
24. The light source of claim 1 , wherein the local length of at least some of the lenslets are pseudorandomly selected.
25. The light source of claim 1 , wherein the diffuser comprises a two-dimensional pseudorandom distribution of lenslets having two or more focal lengths.