Light sources with chip-level integrated diffusers
An embodiment includes a light source. The light source may include a substrate and an integrated diffuser. The substrate may include a first surface and a second surface. The second surface may be opposite the first surface. The integrated diffuser may be integrated at the chip-level and positioned directly on the second surface of the substrate. The integrated diffuser may be configured to receive an optical signal directly 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 that includes a first surface and a second surface, the second surface being opposite the first surface;
an epitaxy layer positioned on the first surface of the substrate;
an optical element formed in the epitaxy layer, the optical element positioned in the epitaxy layer such that an optical signal transmitted by the optical element propagates through the substrate; and
an integrated diffuser positioned directly on the second surface of the substrate, the integrated diffuser configured to receive the optical signal directly 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 after the optical signal propagates through the integrated diffuser, the integrated diffuser including a plurality of lenslets positioned directly on the second surface of the substrate, and the plurality of lenslets includes at least one lenslet that is refractive and at least one lenslet that is diffractive.
2. The light source of claim 1 , wherein: a diameter of the optical signal is sized such that the optical signal impinges at least ten lenslets of the plurality of lenslets at the second surface of the substrate, and the diameter of the optical signal is about thirty microns at the second surface.
3. A light source comprising:
a substrate that includes a first surface and a second surface, the second surface being opposite the first surface;
an epitaxy layer positioned on the first surface of the substrate;
an optical element formed in the epitaxy layer, the optical element positioned in the epitaxy layer such that an optical signal transmitted by the optical element propagates through the substrate; and
an integrated diffuser positioned directly on the second surface of the substrate, the integrated diffuser configured to receive the optical signal directly 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 after the optical signal propagates through the integrated diffuser, the integrated diffuser including a plurality of lenslets positioned at pseudorandom locations on the second surface.
4. The light source of claim 3 , wherein:
lenslets of the plurality of lenslets have two or more different focal lengths;
the two or more focal lengths are pseudorandom;
lenslets of the plurality of lenslets include two or more different diameters; and
the two or more different diameters are in a range of about one-half micron to about five microns.
5. The light source of claim 4 , wherein the integrated diffuser is etched directly into the second surface of the substrate.
6. The light source of claim 5 , wherein the integrated diffuser includes a second portion that includes a polymer overlay that is overlaid directly on an outer surface of the etched portion of the integrated diffuser.
7. The light source of claim 1 , wherein the integrated diffuser is configured such that the particular profile of the resultant beam is controlled over two axes such that the particular profile includes a first dimension in a first direction that is aligned with a first of the two axes and a second dimension in a second direction that is aligned with a second of the two axes.
8. A light source comprising:
a substrate that includes a first surface and a second surface, the second surface being opposite the first surface; and
an integrated diffuser that is integrated at a chip-level and positioned directly on the second surface of the substrate, wherein the integrated diffuser is configured to receive an optical signal directly 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, the integrated diffuser including a plurality of lenslets positioned at pseudorandom locations on the second surface.
9. The light source of claim 8 , wherein:
lenslets of the plurality of lenslets have two or more different focal lengths;
the two or more focal lengths are pseudorandom;
lenslets of the plurality of lenslets include two or more different diameters; and
the two or more different diameters are in a range of about one-half micron to about five microns.
10. The light source of claim 8 , wherein at least a portion of the integrated diffuser is etched directly into the second surface of the substrate.
11. The light source of claim 10 , wherein the integrated diffuser includes a second portion that includes a polymer overlay that is overlaid directly on an outer surface of the etched portion of the integrated diffuser.
12. The light source of claim 8 , further comprising:
an epitaxy layer positioned on the first surface of the substrate; and
an optical element formed in the epitaxy layer, the optical element positioned in the epitaxy layer such that an optical signal transmitted by the optical element propagates through the substrate,
wherein the optical element is not precisely aligned with the integrated diffuser.
13. The light source of claim 12 , wherein:
the optical element includes:
a backside emitting optical source;
a substrate-emitting vertical-cavity surface-emitting laser (VCSEL); or
an array of substrate-emitting VCSELs that are arranged in a non-repeating and non-symmetric pattern and includes up to about one hundred VCSELs;
the optical signal includes:
a wavelength within the infrared spectrum;
a wavelength that is greater than about 900 nanometers; or
a wavelength that is about 940 nanometers or about 1300 nanometers; and
the substrate is comprised of:
gallium arsenide;
gallium nitride;
indium phosphide;
silicon carbide; or
sapphire.
14. The light source of claim 8 , wherein at least a portion of the integrated diffuser is formed on a polymer surface that is attached to the second surface of the substrate.
15. A method of clip-level integration of a diffuser in a light source, the method comprising:
growing an epitaxy layer on a first surface of a substrate, the substrate including the first surface and a second surface that is opposite the first surface;
forming one or more optical elements in the epitaxy layer such that optical signals transmitted by the one or more optical elements propagate through the substrate in a direction towards the second surface; and
positioning an integrated diffuser directly on the second surface such that the integrated diffuser is configured to receive the transmitted optical signals directly from the substrate after the optical signal propagates through the substrate to control a particular profile of a resultant beam of the optical signal after the optical signal propagates through the integrated diffuser, wherein the integrated diffuser includes a plurality of lenslets including at least one lenslet that is refractive and at least one lenslet that is diffractive.
16. The method of claim 15 , further comprising:
forming at least a portion of the integrated diffuser on a polymer surface; and
attaching the polymer surface to the second surface of the substrate,
wherein:
the integrated diffuser is comprised of an ultra violet (UV) curable polymer, and the integrated diffuser is generated using a master UV stamp; or
the integrated diffuser is comprised of a thermoplastic, and the integrated diffuser is generated using a heated stamp that melts a surface of the thermoplastic.
17. The method of claim 15 , further comprising etching at least a portion of the integrated diffuser directly into the second surface of the substrate.
18. The method of claim 17 , further comprising overlaying a polymer overlay on an outer surface of the etched portion of the integrated diffuser.