Multiple wavelength vertical cavity laser array on a patterned substrate

Multiple wavelength vertical cavity laser (VCSEL) arrays are promising sources for ultrahigh capacity optical networks using wavelength division multiplexing (WDM). The emission wavelength of a VCSEL is determined by the laser cavity round trip phase condition, which can be varied across the array by varying the thickness of either the cavity or the dielectric mirror layers. In this work we demonstrate, for the first time, a VCSEL array with a shift in emission wavelength due to an induced cavity thickness variation. The cavity thickness is controlled by a lithographically defined pattern on the substrate back side. This technique allows fabrication of a large number of multi-λ arrays with repeatable wavelength on the same wafer. We have achieved a large VCSEL wavelength shift of 20 nm over a 2 mm array