Low-threshold and high-efficiency operation of 1.5 (mu)m distributed reflector laser with DFB grating and Q-wire DBR sections

A low-threshold and high-efficiency distributed reflector laser consisting of active distributed feedback and quantum-wire distributed Bragg reflector sections has been demonstrated. A threshold current I/sub th/ as low as 2.5 mA ( j/sub th/=190 A/cm/sup 2/), an external differential quantum efficiency from the front facet of 36%, and a submode suppression ratio of 54 dB at a bias current of twice the threshold current were obtained for an active section length of 300 (mu)m with a stripe width of 4.4 (mu)m.