Optically pumped InGaAsP/InP distributed feedback lasers

Electron beam writing and wet chemical etching have been used to form high-quality first- and second-order diffraction gratings on InGaAsP/InP laser structures. Optical pumping of a set of small, 50×200-μm gratings with the period changing in 25 Å increments yields a tunable array of single-mode lasers operating in the 1.5-μm region with a peak power of ∼5 W/facet. The wavelength tunability range of ∼270 Å corresponds to the width of the gain curve of the quaternary structure. Comparison of the first- and second-order gratings fabricated on the same wafer indicates superior performance of the latter.