VCSELS INCLUDING A SUB-WAVELENGTH GRATING FOR WAVELENGTH LOCKING

1 . A vertical cavity surface emitting laser (VCSEL) comprising:

a substrate;

an epitaxial VSCEL structure on the substrate, wherein the epitaxial VSCEL structure includes a resonant cavity, including a gain region, disposed between a first reflector and a partially reflecting second reflector, wherein at least one of the first or second reflectors includes a first sub-wavelength grating to provide spectral control for optical emission from the VCSEL.

2 . The VCSEL of claim 1 wherein the first sub-wavelength grating is operable to lock a wavelength of an optical beam for emission from the VCSEL substantially to a wavelength defined by the grating.

3 . The VCSEL of claim 1 wherein the first sub-wavelength grating is a resonant waveguide grating.

4 . The VCSEL of claim 1 wherein the VCSEL is a top-emitting VCSEL.

5 . The VCSEL of claim 1 wherein the VCSEL is a bottom-emitting VCSEL.

6 . The VCSEL of claim 1 wherein the first sub-wavelength grating is disposed on a side of the gain region opposite a side on which the substrate is disposed.

7 . The VCSEL of claim 6 further including a second sub-wavelength grating on a same side of the gain region as the substrate;

wherein each of the first and second sub-wavelength gratings is a narrow band reflector whose reflectance curves have substantially a same peak.

8 . (canceled)

9 . The VCSEL of claim 1 wherein the first sub-wavelength grating is disposed on a same side of the gain region as the substrate.

10 . The VCSEL of claim 1 wherein the partially reflecting second reflector includes the first sub-wavelength grating.

11 . The VCSEL of claim 1 further including a phase matching layer adjacent the first sub-wavelength grating;

wherein the phase matching layer is composed of AlGaAs.

12 . (canceled)

13 . The VCSEL of claim 1 wherein at least one of the first or second reflectors includes a distributed Bragg reflector.

14 . (canceled)

15 . The VCSEL of claim 1 wherein each of the first and second reflectors includes a respective sub-wavelength grating.

16 . The VCSEL of claim 15 wherein at least one of the first or second reflectors further includes a distributed Bragg reflector.

17 . The VCSEL of claim 15 wherein each of the first and second reflectors further includes a respective distributed Bragg reflector.

18 . The VCSEL of claim 15 including a phase matching layer adjacent at least one of the first or second sub-wavelength gratings.

19 . The VCSEL of claim 15 including a respective phase matching layer adjacent each of the first and second sub-wavelength gratings.

20 . The VCSEL of claim 1 wherein the first sub-wavelength grating is composed of silicon nitride (SiN), silicon oxide (SiO 2 ) or silicon oxynitride (SiO x N y ).

21 . An optical sensor module comprising:

an optical source including a VCSEL according to claim 1 , the VCSEL being operable to generate a source beam directed through a window toward an object;

an optical detector to sense light reflected back from the object illuminated by the narrow divergence source beam; and

a computation device operable to determine a distance to the object or a physical characteristic of the object based at least in part on a signal from the optical detector.

22 . A host device comprising an optical sensor module according to claim 21 , wherein the host device is operable to use data obtained by the optical detector of the optical sensor module for one or more functions executed by the host device.

23 . The host device of claim 22 wherein the host device is a smart phone.