1.5-µm-Wavelength Distributed Feedback Lasers with Deeply Etched First-Order Vertical Grating

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