Size effect of high contrast gratings in VCSELs.

We report on the effects of shrinking the physical size of a high index contrast grating (HCG) on a vertical cavity surface-emitting laser (VCSEL). HCGs previously had been simulated assuming infinite periodicity. Here we probe through simulation and experiment the effect of reducing the HCG to only a few periods. We experimentally realize lasing VCSELs with as few as 4 periods of HCG. By shrinking the HCG to an extremely small size and integrating it on a wavelength tunable VCSEL, we are able to achieve a tunable VCSEL with a record fast mechanical tuning response of >27 MHz. This is a 5X improvement over the fastest previously reported wavelength tunable VCSELs.