Low threshold operation of a GaAlAs/GaAs distributed feedback laser with double channel planar buried heterostructure

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Abstract
We describe a GaAlAs/GaAs distributed feedback (DFB) laser with double channel planar buried heterostructure operating at λ=0.88 μm. The device has been prepared using three-step liquid phase epitaxy. A cw threshold current as low as 12 mA at room temperature has been accomplished even with third-order diffraction gratings. A single longitudinal mode oscillation without mode hopping has been observed at any injection level over a temperature range of 60 K. These characteristics are indeed almost comparable to the well-developed quaternary counterparts, thus showing that the excellent spectral purity of DFB lasers will soon be available in the fields where shorter wavelengths are needed.