Monolithic integration of wavelength-scale diffractive structures on red vertical-cavity lasers by focused ion beam etching

We report the fabrication and characterization of wavelength-scale diffractive optical elements etched directly on the surface of red (660 nm) vertical-cavity surface-emitting lasers. The structures were fabricated by focused ion beam etching. Linear and two-dimensional (2-D) grating configurations were investigated. Each showed excellent suppression of the zeroth-order diffracted beam. Compared to the power from an unetched laser, ∼22% of the emission was coupled into the first order for linear gratings and 12% for the 2-D structures. Polarization was independent of grating orientation for grating pitches as small as 1λ. Threshold current increases of 35%-40% were measured.