1.5-mu m-wavelength distributed feedback lasers with deeply etched first-order vertical grating

1.5-mum-wavelength distributed feedback lasers with a deeply etched first o rder vertical grating were realized for the first time. It was shown that w e can obtain an effective coupling by reducing the stripe width. The sample with the cavity length of 430 mum, 1.8 mum stripe width and 0.2 mum gratin g depth on each lateral side exhibited a 12.5 mA threshold current, 37% tot al differential quantum efficiency and 35 dB submode suppression ratio at a bias current of two times the threshold.