SINGLE-MODE QUANTUM CASCADE LASERS WITH ENHANCED TUNING RANGE

• US 20150110137A1
• Filed: 10/17/2013
• Published: 04/23/2015
• Est. Priority Date: 10/17/2013
• Status: Active Grant

• Current Assignee: The Trustees of Princeton University (Princeton University)
• Original Assignee: Princeton University
• Inventors: Gmachl, Claire F., Zheng, Mei Chai, Liu, Qiang
• Granted Patent: US 9,088,126 B2
• Time in Patent Office: Days
• US Class Current: 372/20
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01S 5/06 Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
• CPC Class Codes: H01S 5/0612 controlled by temperature
• CPC Class Codes: H01S 5/06255 Controlling the frequency of the radiation
• CPC Class Codes: H01S 5/1007 Branched waveguides
• CPC Class Codes: H01S 5/1021 Coupled cavities H01S5/14 takes precedence
• CPC Class Codes: H01S 5/3401 having no PN junction, e.g. unipolar lasers, intersubband lasers, quantum cascade lasers
• CPC Class Codes: Y10S 977/951 Laser

Abstract

In one aspect, semiconductor lasers are provided. A semiconductor laser described herein comprises substrate and a cavity formed on the substrate, the cavity comprising an asymmetric Mach-Zehnder (AMZ) interferometer structure positioned between two straight waveguide segments, the straight waveguide segments and first and second arms of the AMZ interferometer structure comprising epitaxial semiconductor layers, wherein the second arm of the AMZ interferometer structure has a temperature control architecture independent of the first arm.

Claims

1. A single-mode laser comprising:

a substrate; and

a cavity formed on the substrate, the cavity comprising an asymmetric Mach-Zehnder (AMZ) interferometer structure positioned between two straight waveguide segments, the straight waveguide segments and first and second arms of the AMZ interferometer structure comprising epitaxial semiconductor layers, wherein the second arm of the AMZ interferometer structure has a temperature control architecture independent of the first arm operable for expanding a single-mode emission tuning range of the single-mode laser.

2. The single-mode laser of claim 1, wherein the temperature control architecture of the second arm comprises one or more electrical contacts for biasing the second arm independent of biasing the first arm.

3. The single-mode laser of claim 1, wherein the single-mode laser is a quantum cascade laser.

4. The single-mode laser of claim 1, wherein the second arm is longer than the first arm.

5. The single-mode laser of claim 1, wherein the second arm is longer than the first arm by at least 300 μ

m.

6. The single-mode laser of claim 1, wherein the second arm is longer than the first arm by 300 μ

m to 500 μ

m.

7. The single-mode laser of claim 1, wherein light is generated in the cavity and emitted at a straight waveguide segment end.

8. The single-mode laser of claim 1, wherein the single-mode emission tuning range covers 20 cm⁻

1.

9. The single-mode laser of claim 8, wherein single-mode tuning is substantially continuous over the range of 20 cm⁻

1.

10. The single mode laser of claim 1, wherein the epitaxial semiconducting layers comprise alternating layers of III/V semiconductor material.

11. The single mode laser of claim 1, wherein the alternating layers comprise indium gallium arsenide and indium aluminum arsenide.

12. The single mode laser of claim 1, wherein locally symmetric Y-splitter structures join the straight waveguide segments to the AMZ interferometer structure.

13. A method of tuning laser emission comprising:

providing a single-mode semiconductor laser including a substrate and a cavity formed on the substrate, the cavity comprising an asymmetric Mach-Zehnder (AMZ) interferometer structure positioned between two straight waveguide segments, the straight waveguide segments and first and second arms of the AMZ interferometer structure comprising epitaxial semiconductor layers, wherein the second arm of the AMZ interferometer structure has a temperature control architecture independent of the first arm; and

changing temperature of the second arm independently from the first arm to alter single-mode emission wavelength.

14. The method of claim 13, wherein the single-mode emission wavelength is altered over a range of 20 cm⁻

1.

15. The method of claim 13, wherein the temperature control architecture comprises one or more electrical contacts for biasing the second arm independent of biasing the first arm.

16. The method of claim 15, wherein the second arm is biased at a different DC current than the first arm.

17. The method of claim 15, wherein the first arm is maintained at a constant temperature by biasing at a constant DC current, and the temperature of the second arm is changed by independently biasing the second arm at a DC current different from the constant DC current of the first arm.

18. The method of claim 17, wherein the straight waveguide segments are biased at the constant DC current of the first arm.

19. The method of claim 17, wherein the DC current of the second arm increases the single-mode emission wavelength of the laser.

20. The method of claim 17, wherein the DC current of the second arm decreases the single-mode emission wavelength of the laser.

21. The method of claim 16, wherein increasing the DC current on the first arm decreases the single-mode emission wavelength of the laser.

22. The method of claim 16, wherein the DC current of the first arm and DC current of the second arm are selected from a look-up table to produce a desired single-mode emission wavelength from the laser.

23. The method of claim 13, wherein the single mode laser is a quantum cascade laser.

24. The method of claim 13, wherein the second arm is longer than the first arm by at least 300 μ

m.

25. The method of claim 13, wherein the epitaxial semiconductor layers comprise alternating layers of III/V semiconductor material.