Semiconductor laser light source with photocurrent feedback control for single mode operation
View Patent ↗A semiconductor laser, for example a Vertical Cavity Surface Emitting Laser (VCSEL), includes one or more photoactive layers to improve the fundamental mode operation of lasing. The photoactive layer(s) provides on-axis current channeling, resulting from the selective drop in resistance around the center of the photoactive layer(s) due to photo-excitation, and counteracts “hole burning” (i.e., carrier depletion) of the center axis region of the VCSEL cylinder. The photoactive layer(s) act as a variable resistivity screen(s) whose radial aperture is controlled by the light itself. The absorption of a small traction of the light intensity suffices for significant on-axis current peaking with minimum efficiency loss and optical mode distortion. Thus, the VCSEL has optically pumped photoactive layers that induce significant, self-regulated, on-axis current channeling and fundamental mode stability at high operation current, improving lasing operation. Photoactive layers may be fabricated using molecular beam epitaxy and do not require wafer post processing.
1. A method of making an improved optoelectronic light source, comprising the steps of:
forming a plurality of n-doped semiconductor layers;
forming a plurality of p-doped semiconductor layers;
forming an active region between said plurality of n-doped semiconductor layers and said plurality of p-doped semiconductor layers; and
forming a photoresistive layer that provides photocurrent feedback by increasing a current density in the active region by decreasing its resistance in response to light emitted from the active region,
wherein said photoresistive layer is disposed within said optoelectronic light source between the plurality of n-doped semiconductor layers and the plurality of p-doped semiconductor layers, and
wherein the photoresistive layer regulates current passing through the optoelectronic light source by decreasing its resistance in response to light emitted from the active region.
2. The method according to claim 1 , wherein said photoresistive layer is formed using molecular beam epitaxy.
3. The method according to claim 2 , wherein said photoresistive layer is formed integral to formation of said optoelectronic light source.
4. The method according to claim 1 , wherein said optoelectronic light source is a semiconductor laser light source.
5. The method according to claim 4 , wherein said plurality of n-doped semiconductor layers is a first Bragg mirror and said plurality of p-doped semiconductor layers is a second Bragg mirror.
6. The method according to claim 4 , wherein said photoresistive layer is formed within said plurality of n-doped semiconductor layers.
7. The method according to claim 4 , wherein said photoresistive layer is formed at a location in said optoelectronic light source so as to minimize premature photo current saturation and current clipping.
8. The method according to claim 4 , wherein said photoresistive layer is formed at a location in said optoelectronic light source where a minimum of a light intensity occurs.
9. The method according to claim 4 , further comprising the step of forming another photoresistive layer within said optoelectronic light source, wherein said photoresistive layer is formed within said plurality of n-doped semiconductor layers and said another photoresistive layer is formed within said p-doped semiconductor layers.
10. The method according to claim 4 , wherein said photoresistive layer is formed within said plurality of p-doped semiconductor layers.
11. The method according to claim 1 , further comprising the step of forming another photoresistive layer within said optoelectronic light source, wherein said photoresistive layer is formed within a plurality of n-doped semiconductor layers and said another photoresistive layer is formed within a p-doped semiconductor layers.
12. A method of making an improved optoelectronic light source, comprising the steps of:
forming a plurality of n-doped semiconductor layers;
forming a plurality of p-doped semiconductor layers;
forming an active region between said plurality of n-doped semiconductor layers and said plurality of p-doped semiconductor layers; and
forming a photoresistive layer that provides photocurrent feedback by increasing a current density in the active region by decreasing its resistance in response to light emitted from the active region,
wherein said photoresistive layer is disposed within one or both of the plurality of n-doped semiconductor layers and the plurality of p-doped semiconductor layers, and
wherein the photoresistive layer regulates current passing through the optoelectronic light source by decreasing its resistance in response to light emitted from the active region.
13. The method according to claim 12 , wherein said optoelectronic light source is a semiconductor laser light source.
14. The method according to claim 13 , wherein said plurality of n-doped semiconductor layers is a first Bragg mirror and said plurality of p-doped semiconductor layers is a second Bragg mirror.
15. The method according to claim 13 , wherein said photoresistive layer is formed within said plurality of n-doped semiconductor layers.
16. The method according to claim 13 , wherein said photoresistive layer is formed at a location in said optoelectronic light source so as to minimize premature photo current saturation and current clipping.
17. The method according to claim 13 , wherein said photoresistive layer is formed at a location in said optoelectronic light source where a minimum of a light intensity occurs.
18. The method according to claim 13 , further comprising the step of forming another photoresistive layer within said optoelectronic light source, wherein said photoresistive layer is formed within said plurality of n-doped semiconductor layers and said another photoresistive layer is formed within said p-doped semiconductor layers.
19. The method according to claim 13 , wherein said photoresistive layer is formed within said plurality of p-doped semiconductor layers.
20. The method according to claim 12 , further comprising the step of forming another photoresistive layer within said optoelectronic light source, wherein said photoresistive layer is formed within a plurality of n-doped semiconductor layers and said another photoresistive layer is formed within a p-doped semiconductor layers.