High fill-factor efficient vertical-cavity surface emitting laser arrays
View Patent ↗An array of vertical-cavity surface emitting lasers (VCSELs) may be fabricated with very high fill-factors, thereby enabling very high output power densities during pulse, quasi-continuous wave (QCW), and continuous wave (CW) operation. This high fill-factor is achieved using asymmetrical pillars in a rectangular packing scheme as opposed prior art pillar shapes and packing schemes. The use of asymmetrical pillars maintains high efficiency operation of VCSELs by maintaining minimal current injection distance from the metal contacts to the laser active region and by maintaining efficient waste heat extraction from the VCSEL. This packing scheme for very high fill-factor VCSEL arrays is directly applicable for next generation high-power, substrate removed, VCSEL arrays.
1. An apparatus comprising:
a semiconductor region;
a first row of at least one vertical-cavity surface emitting laser (VCSEL) formed on the semiconductor region; and
a second row of at least one VCSEL formed on the semiconductor region and separated from the first row by a current confinement separator; wherein
each VCSEL includes an output aperture having a length and a width,
a ratio of the aperture length to the aperture width is in a range of 2.5:1 to at least 4:1,
a ratio of the aperture width to a distance between apertures of the VCSEL(s) of the first and second row is at most two-to-one, and
at least 10% of a surface area of the semiconductor region corresponds to surface areas of the apertures of the first and second row of VCSEL(s).
2. The apparatus of claim 1 , wherein the current confinement separator comprises a row trench, and each VCSEL further includes an aperture layer forming the aperture and having a width greater than the width of the aperture by a first value, wherein a ratio of the aperture width to the sum of the first value and a width of the row trench is at most two-to-one.
3. The apparatus of claim 1 , wherein the ratio of the aperture length to the aperture width is at least four-to-one.
4. The apparatus of claim 1 , wherein at least 25% of the surface area of the semiconductor region corresponds to surface areas of the apertures of the first and second row of VCSEL(s).
5. The apparatus of claim 1 , wherein the first and second row of VCSEL(s) each comprise a plurality of VCSELs separated by a column trench.
6. The apparatus of claim 5 , wherein the column trench of the first row of VCSELs is aligned with the column trench of the second row of VCSELs.
7. The apparatus of claim 5 , wherein the column trench of the first row of VCSELs is offset with respect to the column trench of the second row of VCSELs.
8. The apparatus of claim 5 , wherein a length of the column trench is not equal to the width of the row trench.
9. The apparatus of claim 1 , wherein each aperture of the VCSEL(s) of the first and second row comprises a relatively rectangular shape.
10. The apparatus of claim 1 , wherein each aperture of the VCSEL(s) of the first and second row comprises a relatively oval shape.
11. The apparatus of claim 1 , wherein each aperture of the VCSEL(s) of the first and second row comprises a polygon of non-parallel sides, the sides angled to suppress in-plane optical feedback.