The fabrication of grating for 1.55 /spl mu/m InGaAsP DFB laser array by e-beam lithography

First-order and second-order gratings for the 1.55 /spl mu/m wavelength InGaAsP laser have been fabricated by e-beam lithography on the InP substrate. The pattern is transferred into the InP substrate by wet chemical etching using HNO/sub 3/:HBr:H/sub 2/O and reactive ion etching using the gas mixture CH/sub 4/:H/sub 2/:Ar/sub 2/. The experimental results have proven that a PMMA resist of 200 nm thickness can not only stand up to wet chemical etching but also to reactive ion etching.