Multiple-wavelength VCSEL array by grading a spacer layer for WDM applications

In this paper we present a 0.98 mum 4-channel VCSEL array fabricated with grading a SiO2 spacer layer. A maximum of 5.4 nm wavelength span has achieved using 8.5 pairs of SiO₂/Ta₂O₅ mirror. Also, surface nanomachining process is presented for making on-wafer precise spacer-layer gradients.