VCSEL device with multiple stacked active regions
Methods, devices and systems are described for enabling a series-connected, single chip vertical-cavity surface-emitting laser (VCSEL) array. In one aspect, the single chip includes one or more non-conductive regions one the conductive layer to produce a plurality of electrically separate conductive regions. Each electrically separate region may have a plurality of VCSEL elements, including an anode region and a cathode region connected in series. The chip is connected to a sub-mount with a metallization pattern, which connects each electrically separate region on the conductive layer in series. In one aspect, the metallization pattern connects the anode region of a first electrically separate region to the cathode region of a second electrically separate region. The metallization pattern may also comprise cuts that maintain electrical separation between the anode and cathode regions on each conductive layer region, and that align with the etched regions.
1. A VCSEL array device, comprising:
a semiconductor substrate;
two or more VCSEL devices, each VCSEL device comprising:
a first mesa on top of the semiconductor substrate, each first mesa forming a first side and including a lower mirror in contact with the semiconductor substrate,
an upper mirror,
a plurality of epitaxially stacked active regions electrically joined with reverse tunnel junctions, each active region generating a light and positioned between the lower mirror and the upper mirror, and
a first metal contact pad in electrical contact with the upper mirror;
one or more short-circuited devices, each-short circuited device among the one or more short-circuited devices forming a second mesa on top of the semiconductor substrate, each second mesa forming a second side and including a second metal contact pad electrically connected to the semiconductor substrate;
a plurality of metal heat sink structures deposited over each VCSEL device and each short circuited device, a first set of heat sink structures among the plurality of metal heat sink structures deposited over each VCSEL device, the first set of heat sink structures electrically connected to the first metal contact pad and electrically isolated from the semiconductor substrate, a second set of heat sink structures among the plurality of metal heat sink structures deposited over each short-circuited device and electrically connected to the second metal contact pad and electrically isolated from the first set of heat sink structures; and
a heat-spreading substrate bonded to the first set of heat sink structures and the second set of heat sink structures.
2. The VCSEL array device as recited in claim 1 , wherein a layer of a dielectric material is positioned between at least the first side and a portion of an upper surface of the upper mirror and the first set of heat sink structures.
3. The VCSEL array device as recited in claim 1 , further comprising a bonding layer between the heat-spreading substrate and the first set of heat sink structures and the second set of heat sink structures.
4. The VCSEL array device as recited in claim 3 , wherein the first set of heat sink structures and the second set of heat sink structures are flip-chip bonded to the heat-spreading substrate.
5. The VCSEL array device as recited in claim 4 , wherein the two or more VCSEL devices are connected in parallel, further comprising a ground plane surrounding substantially all of the two or more VCSEL devices forming a coplanar waveguide lead and electrically connected to the second metal contact pad of each short circuited device to form a ground-signal-ground configuration.
6. The VCSEL array device as recited in claim 5 , wherein the second metal contact pad of each short circuited device is electrically connected to the ground plane without wire bonding.
7. The VCSEL array device as recited in claim 4 , wherein the two or more VCSEL devices are connected in parallel, further comprising a ground plane completely surrounding the two or more VCSEL devices forming a coplanar waveguide lead and electrically connected to the second metal contact pad of each short circuited device to form a ground-signal-ground configuration.
8. The VCSEL array device as recited in claim 1 , wherein the two or more VCSEL devices further include a containment region positioned between the active region and the first metal contact pad, the containment region defining an aperture reducing capacitance within the first mesa.
9. The VCSEL array device as recited in claim 1 , further comprising a set of lenses positioned over the two or more VCSEL devices.
10. The VCSEL array device as recited in claim 9 , wherein each lens in the set of lenses is positioned over each VCSEL device by an offset distance necessary to direct the light to a location.
11. The VCSEL array device as recited in claim 1 , wherein the VCSEL array device is used as an emitter for high speed data communication in at least one of an optical fiber and an optical free space.
12. The VCSEL array device as recited in claim 1 , wherein the VCSEL array device is used as a short pulse emitter for material processing or an optical pump.
13. The VCSEL array device as recited in claim 1 , wherein the VCSEL array device is used as a pulsed emitter for laser detection and ranging or light detection and ranging.
14. The VCSEL array device as recited in claim 1 , wherein the VCSEL array device is used in at least one of a beam steering device and an illuminating device.
15. The VCSEL array device as cited in claim 1 , wherein each epitaxially stacked active region among the plurality of epitaxially stacked active regions comprises a multi-quantum well (MQW) made of a same or a different bandgap MQW.
16. The VCSEL array device as cited in claim 15 , wherein each epitaxially stacked active region includes an oxide confinement layer.
17. The VCSEL array device as cited in claim 1 , wherein each epitaxially stacked active region among the plurality of epitaxially stacked active regions is surrounded by an implant confinement layer.
18. The VCSEL array device as cited in claim 17 , wherein the reverse tunnel junction extends through the implant confinement layer, and wherein a top-most active region contains an oxide confinement layer.
19. The VCSEL array device as cited in claim 1 , wherein each epitaxially stacked active region among the plurality of epitaxially stacked active regions has a different gain offset.
20. The VCSEL device, comprising:
a semiconductor substrate;
at least one series-connected VCSEL array, each VCSEL array comprising a semiconductor die including a semiconductor substrate and a conductive cathode layer, a sub-mount including a metallization pattern to serially connect a plurality of electrically conductive regions, each comprising:
two or more VCSEL element, each VCSEL element comprising:
a first mesa on top of the semiconductor substrate, each first mesa forming a first side and including a lower mirror in contact with the semiconductor substrate,
an upper mirror,
a plurality of epitaxially stacked active regions electrically joined with reverse tunnel junctions, each active region generating a light and positioned between the lower mirror and the upper mirror, and
a first metal contact pad in electrical contact with the upper mirror;
one or more short-circuited devices, each-short circuited device among the one or more short-circuited devices forming a second mesa on top of the semiconductor substrate, each second mesa forming a second side and including a second metal contact pad electrically connected to semiconductor substrate;
a plurality of metal heat sink structures deposited over each VCSEL element and each short circuited device, a first set of heat sink structures among the plurality of metal heat sink structures deposited over each VCSEL element, the first set of heat sink structures electrically connected to the first metal contact pad and electrically isolated from the semiconductor substrate, a second set of heat sink structures among the plurality of metal heat sink structures deposited over each short-circuited device and electrically connected to the second metal contact pad and electrically isolated from the first set of heat sink structures; and
a heat-spreading substrate bonded to the first set of heat sink structures and the second set of heat sink structures.