InGaP/InAsP MQW complex-coupled DFB taperless laser with large spot size and high coupling efficiency

The authors report a novel large spot size complex-coupled DFB laser, without a mode converter and using an MQW core structure with a low effective refractive index. It operates on a singlemode basis with an SMSR as high as 40 dB and a linewidth as narrow as 2 MHz, and provides good coupling characteristics into cleaved optical fibres. The device was fabricated by a conventional buried heterostructure laser process and the grating was provided by partly etching the well stack