Tunable VCSEL with combined gain and DBR mirror
A vertical cavity surface emitting laser (VCSEL) has a shortened overall laser cavity by combining the gain section with a distributed Bragg reflector (DBR). The overall cavity length can be contracted by placing gain structures inside the DBR. This generally applies to a number of semiconductor material systems and wavelength bands, but this scheme is very well suited to the AlGaAs/GaAs material system with strained InGaAs quantum wells as a gain medium, for example.
1. A vertical surface emitting laser, comprising:
a distributed Bragg reflector mirror, comprising a plurality of high/low refractive index layer pairs;
a deflectable membrane carrying a second mirror defining an optical cavity of the vertical surface emitting laser, wherein the deflectable membrane is configured to tune the vertical surface emitting laser emission across a plurality of wavelengths; and
quantum wells located in the distributed Bragg reflector, wherein the quantum wells are positioned to overlap with antinodes of the plurality of wavelengths, wherein at least one quantum well is located inside a high refractive index layer of the plurality of high/low refractive index layer pairs such that the at least one quantum well has a high refractive index barrier on each side of the at least one quantum well, and wherein the high refractive index layer has an optical thickness larger than one quarter wavelength and less than one half wavelength at the center wavelength of the distributed Bragg reflector.
2. The laser of claim 1 , wherein the quantum wells are located in shallow layers of the distributed Bragg reflector.
3. The laser of claim 1 , wherein the quantum wells located inside the distributed Bragg reflector are fabricated in AlGaAs/GaAs materials.
4. The laser of claim 1 , wherein the quantum wells are located between high index layers and low index layers of the distributed Bragg reflector.
5. The laser of claim 1 , wherein the quantum wells comprise eight four or more quantum wells.
6. The laser of claim 1 , wherein the quantum wells of the vertical surface emitting laser are configured to be optically pumped.
7. The vertical surface emitting laser of claim 1 , wherein the at least one quantum well is located inside a high refractive index layer of the plurality of high/low refractive index layer pairs such that the at least one quantum well has a high refractive index barrier on each side of the at least one quantum well, and wherein the pairs have a combined optical thickness of half a wavelength at a center wavelength of the distributed Bragg reflector.
8. The vertical surface emitting laser of claim 1 , wherein the deflectable membrane is configured to tune the vertical surface emitting laser emission across the plurality of wavelengths by out of plane electrostatic deflection of the deflectable membrane.
9. The vertical surface emitting laser of claim 1 , where a center wavelength is between 1.0-1.35 μm.
10. The vertical surface emitting laser of claim 1 , wherein a pair of high/low refractive index layers, having a combined thickness of half a wavelength at a center wavelength of the distributed Bragg reflector, comprises high/low layers having optical thicknesses of 63/37 percent, respectively.
11. The vertical surface emitting laser of claim 1 , wherein a pair of high/low refractive index layers, having a combined thickness of half a wavelength at a center wavelength of the distributed Bragg reflector, comprises high/low layers having optical thicknesses of 75/25 percent, respectively.
12. A vertical surface emitting laser system, comprising:
a vertical surface emitting laser, comprising:
a distributed Bragg reflector mirror comprising:
a plurality of high/low refractive index layer pairs, wherein the pairs have a combined optical thickness of half a wavelength at a center wavelength of the distributed Bragg reflector; and
at least one quantum well located inside a high refractive index layer of the plurality of high/low refractive index layer pairs such that the at least one quantum well has a high refractive index barrier on each side of the at least one quantum well, and wherein the high refractive index layer has an optical thickness larger than one quarter wavelength at the center wavelength of the distributed Bragg reflector;
a deflectable membrane carrying a mirror defining an optical cavity of the vertical surface emitting laser, wherein the deflectable membrane is configured to tune the vertical surface emitting laser emission across a plurality of wavelengths; and
a pump laser for optically pumping the at least one quantum well.
13. The system of claim 12 , wherein the at least one quantum well is located in the distributed Bragg reflector which is fabricated in AlGaAs/GaAs materials.
14. The vertical surface emitting laser system of claim 12 , where the center wavelength is between 1.0-1.35 μm.
15. The vertical surface emitting laser system of claim 12 , wherein the at least one quantum well is positioned to overlap with antinodes of the plurality of wavelengths.
16. The vertical surface emitting laser system of claim 12 , wherein the at least one quantum well is located in shallow layers of the distributed Bragg reflector.
17. The vertical surface emitting laser system of claim 12 , wherein a pair of high/low refractive index layers comprises high/low layers having optical thicknesses of 63/37 percent, respectively.
18. The vertical surface emitting laser system of claim 12 , wherein a pair of high/low refractive index layers comprises high/low layers having optical thicknesses of 75/25 percent, respectively.