Wavelength-tunable VCSEL polarization control using a cavity-based subwavelength grating

Abstract

A very powerful selection mechanism is provided in tunable vertical cavity surface emitting lasers (VCSELs) by manipulating the laser threshold differently for TE and TM polarizations by employing a subwavelength grating in the laser cavity. The laser selects the polarization with the lowest threshold. The grating does not diffract and adds no loss to the cavity. It works by creating a large birefringent layer between the semiconductor and the air subcavity across the VCSEL. Multilayer stack calculations show that this results in a lower threshold for TM polarization over TE. This subwavelength grating layer replaces the AR coating on the semiconductor surface in one embodiment.

Claims

1. A tunable vertical cavity surface-emitting laser (VCSEL), wherein the tunable vertical cavity surface-emitting laser (VCSEL) is A deformable film element having a mirror, and a semi-VCSEL defining the optical cavity of the laser, The subwavelength grating in the optical cavity and It is equipped with, The subwavelength grating is a tunable vertical cavity surface-emitting laser (VCSEL) with a duty cycle of 50%.

2. The laser according to claim 1, wherein the subwavelength grating is located on the half-VCSEL.

3. The laser according to claim 1, wherein the subwavelength grating is formed on the upper high refractive index layer of the half-VCSEL.

4. The laser according to claim 1, wherein the semi-VCSEL includes a dispersed Bragg reflector (DBR).

5. The laser according to claim 1, wherein the subwavelength grating is composed of alternating materials and air.

6. The laser according to claim 1, wherein the subwavelength grating is composed of alternating InGaP and air.

7. The laser according to claim 1, wherein the subwavelength grating replaces the anti-reflective coating on the half-VCSEL.

8. A method for fabricating a tunable vertical cavity surface-emitting laser (VCSEL), wherein the method is: Forming a deformable film element and a semi-VCSEL element that defines the optical cavity of the laser, Forming a subwavelength grating within the half-VCSEL element Includes, The subwavelength grating has a duty cycle of 50%.

9. A tunable vertical cavity surface-emitting laser (VCSEL) system, wherein the VCSEL system is A laser comprising a deformable film element having a mirror, a half-VCSEL defining the optical cavity of the laser, and a subwavelength grating within the optical cavity, An excitation chip for optically exciting the laser and The VCSEL system is equipped with this feature.

10. The VCSEL system according to claim 9, wherein the subwavelength grating is located on the half VCSEL.

11. The VCSEL system according to claim 9, wherein the subwavelength grating is formed on the upper high refractive index layer of the half-VCSEL.

12. The laser is configured to emit light at least at wavelength (λ), The subwavelength grating is formed within the material in the optical cavity, and the material has a refractive index (n). The VCSEL system according to claim 9, wherein the subwavelength grating has a pitch (Λ) less than λ / n.

13. The VCSEL system according to claim 9, wherein the subwavelength grating is formed by lithography.

14. The VCSEL system according to claim 9, wherein the semi-VCSEL includes a dispersed Bragg reflector (DBR).

15. The VCSEL system according to claim 14, wherein the DBR is a dichroic mirror filter.

16. The VCSEL system according to claim 14, wherein the DBR comprises alternating layers of a high refractive index material and a low refractive index material.

17. The VCSEL system according to claim 9, wherein the subwavelength grating has a duty cycle of 50%.

18. The VCSEL system according to claim 9, wherein the subwavelength grating is made of alternating materials and air.

19. The VCSEL system according to claim 9, wherein the subwavelength grating is alternating InGaP and air.

20. The VCSEL system according to claim 9, wherein the subwavelength grating replaces the anti-reflective coating on the half-VCSEL.

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