Compact sub-micron focused laser beam using integrated Bessel phase control

We report the integration of phase gratings directly onto the surface of red vertical cavity surface emitting lasers (VCSELs) by Focused Ion Beam etching. Gratings have been used to generate quasi Bessel beams. The fabricated devices show that a diffraction limited central spot can be formed above the surface of the device. The narrow spot has a full width at half maximum of 0.5μm at a distance of 2μm above the VCSEL surface. The compact device can be formed in arrays and can be considered for a large number of sensing applications such as an optical probe for biophotonics and in optical recording systems.