1.55-(mu)m spot-size converter integrated laser diode with conventional buried-heterostructure laser process

A 1.55-(mu)m spot-size converter integrated laser diode is demonstrated with conventional buriedheterostructure laser process. For the spot-size converter, we employed a double-waveguide structure in which a ridge-based passive waveguide was incorporated. The passive waveguide was optically combined with a laterally tapered active waveguide to control mode size. The threshold current was measured to be 5 mA together with high slope efficiency of 0.45 W/A. The beam divergence angles in the horizontal and vertical directions were as small as 9.0(degree) and 7.8(degree), respectively.