All-active tapered 1.55-μm InGaAsP BH-DFB laser with continuously chirped grating

We demonstrate the first realization of all-active tapered index coupled 1.55-μm InGaAsP buried-heterostructure distributed feedback lasers involving chirped gratings. The variation of the effective refractive index along the tapered active stripe is compensated using an optimized continuously chirped grating. The grating has been formed using a novel direct-write electron-beam lithography technique. Lasers with an antireflection/cleaved cavity show stable single-mode operation and high optical output power up to 60 mW. The yield of lasers with a sidemode suppression ration > 40 dB is more than 70%. The -3-dB farfield angles (full-width at half-maximum) amount to 14/spl deg/ and 20/spl deg/ in lateral and vertical direction, respectively.