Narrowband Surface Grating (NSG) Mirrors for Wavelength and Polarization Selection, Locking, and Tuning of Vertical Cavity Surface Emitting Lasers

VCSELs (vertical cavity surface emitting lasers) have many advantages over EELs (edge-emitting lasers), such as single-longitudinal mode operation, circular beam, better beam quality (low divergence), low threshold, on-wafer testing and packaging, easiness in making laser arrays, etc. However, to have high output power while keeping all those inherent advantages is a challenge for VCSELs. Furthermore, both wavelength and polarization selection and locking for VCSELs (and any laser) are crucial for many applications, for instance, applications that require highly coherent laser beams. VECSELs (Vertical Extended Cavity Surface Emitting Lasers) can be one solution to achieve high output power while keeping all the inherent advantages of the VCSELs. However, the wavelength and polarization selection and locking could be even more challenging for VECSLEs compared to VCSELs. We propose to use a narrow band surface grating waveguide resonant filter (NSG) as an external cavity feedback mirror to select and lock both the wavelength and polarization of the VCSELs.