1.55 mu m single mode lasers with complex coupled distributed feedback gratings fabricated by focused ion beam implantation

Complex coupled GaInAsP/InP distributed feedback lasers were developed base d on maskless focused ion beam lithography. By combining implantation enhan ced wet chemical etching and implantation induced thermal quantum well inte rmixing a refractive index grating was defined self-aligned to a gain grati ng forming a complex coupled grating lateral to a ridge waveguide. The devi ces show single mode emission at wavelengths around 1.55 mu m with linewidt hs < 2 MHz and side mode suppression ratios of more than 40 dB for continuo us wave operation at room temperature. A high single mode yield (> 90%) ove r a large tuning range (88 nm) was achieved. (C) 1999 American Institute of Physics. [S0003-6951(99)00137-0].