Applications of Guided-mode resonant filters to VCSELs

Within the last 2 years Vertical Cavity Surface Emitting Lasers (VCSELs) have emerged from the research laboratory into the commercial marketplace as the component of choice for numerous applications, supplanting both LED and edge-emitting sources. The enormous success of VCSELs is attributed, in part, to their premium performance, producibility, and packaging perks. Namely, significantly lower operating currents and power dissipation at Gb/s data rates; wafer-level batch fabrication, testing, and utilization of the existing LED and III-V manufacturing infrastructure; more efficient coupling into fibers and simplified drive electronics.1 These attributes result directly from the laser’s inherent vertical geometry. This vertical cavity is essentially a zero-order thin-film Fabiy-Perot transmission filter, utilizing integral quarter-wave high-reflectance (> 99%) interference stacks referred to as distributed Bragg reflectors (DBRs). On a parallel front, it has recently been suggested that high reflectivity possible from guided-mode grating resonant filters (GMGRFs)2–4 may likewise serve to construct the high-Finesse vertical cavity, requiring minimal layers. These "resonant reflectors" may be designed to provide ultra-narrow bandwidth filters for a selected center wavelength and polarization with ≅100% in-band reflectance and ~30dB sideband suppression. These are very attractive properties for VCSELs and offer the potential as an enabling tool for modal engineering.