Quantum cascade laser
View Patent ↗A quantum cascade laser utilizing non-resonant extraction design having a multilayered semiconductor with a single type of carrier; at least two final levels ( 1 and 1′ ) for a transition down from level 2 ; an energy spacing E 21 greater than E LO ; an energy spacing E 31 of about 100 meV; and an energy spacing E 32 about equal to E LO . The carrier wave function for level 1 overlaps with the carrier wave function for level 2 . Likewise, the carrier wave function for level 1 ′ overlaps with the carrier wave function for level 2 . In a second version, the basic design also has an energy spacing E 54 of about 90 meV, and levels 1 and 1 ′ do not have to be spatially close to each other, provided that level 2 has significant overlap with both these levels. In a third version, there are at least three final levels ( 1, 1′ , and 1″ ) for a transition down from level 2 . Each of the levels 1, 1′ , and 1″ has a non-uniform squared wave function distribution.
1. A quantum cascade laser utilizing non-resonant extraction design, the quantum cascade laser comprising:
(a) a semiconductor with only one type of carrier, the carrier being electrons, the semiconductor having multiple layers of In x Ga 1-x As/Al y In 1-y As/InP and having at least twenty gain stages, each gain stage comprising multiple In x Ga 1-x As layers having a thickness between about 1 to 5 nanometers and multiple Al y In 1-y As layers having a thickness between about 1 to 5 nanometers, being quantum wells and barriers, respectively, the semiconductor having an active region and an energy relaxation region, the active region having at least lour quantum well/barrier pairs;
(b) an electric current injected along an x-axis perpendicular to the multiple layers;
(c) an insulator to confine the electric current under a contact stripe and to prevent the electric current from spreading in a y-axis parallel to the multiple layers;
(d) at least two final levels, denoted here as levels 1 and 1 ′, for a transition down from a level 2 , levels 1 and 1 ′ being spaced at about 18 meV, a carrier wave function for level 1 overlapping with a carrier wave function for level 2 , a carrier wave function for level 1 ′ overlapping with a carrier wave function for level 2 ;
(e) an energy spacing E 21 greater than E LO and being about 70 mcV;
(f) an energy spacing E 31 of about 100 meV;
(g) an energy spacing E 32 equal to E LO ;
(h) a total optical power greater than 1.5 W at 300K; and
(i) a wall plug efficiency greater than 8.5%.
2. A quantum cascade laser utilizing non-resonant extraction design, the quantum cascade laser comprising:
(a) a semiconductor with a single type of carrier, the semiconductor having multiple layers of gain stages, each gain stage comprising multiple layers with alternating bandgap values;
(b) an electric current injected along an x-axis perpendicular to the multiple layers;
(c) an insulator to confine the electric current under a contact stripe and to prevent the electric current from spreading in a y-axis parallel to the multiple layers;
(d) at least two final levels, designated here as 1 and 1 ′, for a transition down from a level 2 , levels 1 and 1 ; a carrier wave function for level 1 overlapping with a carrier wave function for level 2 , a carrier wave function for level 1 ′ overlapping with a carrier wave function for level 2 ;
(e) an energy spacing E 21 greater than E LO ;
(f) an energy spacing E 31 of about 100 meV; and
(g) an energy spacing E 32 equal to E LO .
3. The quantum cascade laser of claim 2 , the single type of carrier being electrons.
4. The quantum cascade laser of claim 2 , the semiconductor having multiple layers of In x Ga 1-x As/Al y In 1-y As/InP and having at least twenty gain stages, each gain stage comprising multiple In x Ga 1-x As layers having a thickness between about 1 to 5 nanometers and multiple Al y In 1-y As layers having a thickness between about 1 to 5 nanometers, being quantum wells and barriers, respectively.
5. The quantum cascade laser of claim 2 , the levels 1 and 1 ′ being spaced at about 18 meV.
6. The quantum cascade laser of claim 2 , the energy spacing E 21 being about 70 mcV.
7. The quantum cascade laser of claim 2 , further having a total optical power greater than 1.5 W at 300K.
8. The quantum cascade laser of claim 2 , further having a total optical power output and an electrical power input, the product of the total optical power output divided by the electrical power input being greater than 8.5%.
9. The quantum cascade laser of claim 2 , the semiconductor having multiple layers of In x Ga 1-x As/Al y Ga 1-y As/GaAs and having at least twenty gain stages, each gain stage comprising multiple In x Ga 1-x As layers and multiple Al y Ga 1-y As layers.
10. The quantum cascade laser of claim 2 , the semiconductor having multiple layers of In x Ga 1-x As/AlAs y Sb 1-y /InP and having at least twenty gain stages, each gain stage comprising multiple In x Ga 1-x As layers and multiple AlAs y Sb 1-y layers.
11. The quantum cascade laser of claim 2 , the semiconductor having multiple layers of InAs/AlSb/InAs and having at least twenty gain stages, each gain stage comprising multiple InAs layers and multiple AlSb layers.
12. The quantum cascade laser of claim 2 , the semiconductor having multiple layers of Si/SiGe/SiGe and having at least twenty gain stages, each gain stage comprising multiple Si layers and multiple SiGe layers.
13. The quantum cascade laser of claim 2 , the semiconductor having multiple layers of Si/SiGe/Si and having at least twenty gain stages, each gain stage comprising multiple Si layers and multiple SiGe layers.
14. A quantum cascade laser utilizing non-resonant extraction design and with increased E 54 spacing, the quantum cascade laser comprising:
(a) a semiconductor with a single type of carrier, the semiconductor having multiple layers of gain stages, each gain stage comprising multiple layers with alternating bandgap values;
(b) an electric current injected along an x-axis perpendicular to the multiple layers;
(c) an insulator to confine the electric current under a contact stripe and to prevent the electric current from spreading in a y-axis parallel to the multiple layers;
(d) at least two final levels, here denoted 1 and 1 ′, for a transition down from a level 2 , levels 1 and 1 ′, a carrier wave function for level 1 overlapping with a carrier wave function for level 2 , a carrier wave function for level 1 ′ overlapping with a carrier wave function for level 2 ;
(e) an energy spacing E 21 greater than E LO ;
(f) an energy spacing E 31 of about 100 meV;
(g) an energy spacing E 32 equal to E LO ; and
(h) an energy spacing E 54 of about 90 meV.
15. The quantum cascade laser of claim 14 , the single type of carrier being electrons.
16. The quantum cascade laser of claim 14 , the semiconductor having multiple layers of In x Ga 1-x As/Al y In 1-y As/InP and having at least twenty gain stages, each gain stage comprising multiple In x Ga 1-x As layers having a thickness between about 1 to 5 nanometers and multiple Al y In 1-y As layers having a thickness between about 1 to 5 nanometers, being quantum wells and harriers, respectively.
17. The quantum cascade laser of claim 14 , the energy spacing E 21 being about 60 mcV.
18. The quantum cascade laser of claim 14 , wherein the laser has a total optical power greater than 2.0 W at 300K.
19. A quantum cascade laser utilizing non-resonant extraction design and providing vertical transition and fast extraction without delocalization of the states below a level 3 , the quantum cascade laser comprising:
(a) a semiconductor with a single type of carrier, the semiconductor having multiple layers of gain stages, each gain stage comprising multiple layers with alternating bandgap values;
(b) an electric current injected along an x-axis perpendicular to the multiple layers;
(c) an insulator to confine the electric current under a contact stripe and to prevent the electric current from spreading in a y-axis parallel to the multiple layers;
(d) three final levels, denoted here as 1 , 1 ′, and 1 ″, for a transition down from a level 2 , levels 1 and 1 ′, each or the levels 1 , 1 ′, and 1 ″ having a non-uniform squared wave function distribution;
(e) an energy spacing E 21 greater than E LO ;
(f) an energy spacing E 31 of about 100 meV; and
(g) an energy spacing E 32 equal to E LO .
20. The quantum cascade laser of claim 19 , the single type of carrier being electrons.
21. The quantum cascade laser of claim 19 , the semiconductor having multiple layers of In x Ga 1-x As/Al y In 1-y As/InP and having at least twenty gain stages, each gain stage comprising multiple In x Ga 1-x As layers having a thickness between about 1 to 5 nanometers and multiple Al y In 1-y As layers having a thickness between about 1 to 5 nanometers, being quantum wells and barriers, respectively.
22. The quantum cascade laser of claim 19 , the levels 1 and 1 ′ being spaced at about 20 meV, and the levels 1 ′ and 1 ″ being spaced at about 18 meV.
23. The quantum cascade laser of claim 19 , the energy spacing E 21 being about 80 meV.
24. The quantum cascade laser of claim 19 , further having a total optical power greater than 1.5 W at 300K.
25. The quantum cascade laser of claim 19 , further having a wall plug efficiency greater than 8.5%.