We have fabricated 3D printed micro-optics to feedback light into an 850-nm VCSEL with reduced top-mirror reflectivity and control its transverse modes. Our goal is to create a single-frequency VCSEL with output power on the order of 10 mW for use in atomic and quantum physics. Feedback of 50% can reduce threshold current 5-fold and preferentially select the fundamental transverse mode. We will compare theory and experiment for micro-optic length scales near 100 microns, yielding Gaussian mode diameters near 10 microns.
We report on the design and characterization of multi-mirror vertical-cavity surface-emitting lasers (VCSELs) that achieve linewidths less than 2 MHz. We have fabricated all-semiconductor multi-mirror VCSELs at 850 nm that operate in a single mode and are suitable for high-resolution spectroscopy. Cold-cavity linewidth measurements confirm increased quality factors relative to standard VCSEL resonators. Frequency noise power spectral density measurements exhibit 1/f noise and white-noise floors consistent with Lorentzian linewidths less than 2 MHz.