High-coupling efficiency of a 1.3-mu m spot-size converter integrated laser diode with pn-buried heterostructure for high-temperature operation

We propose a novel design concept for low-loss coupling with high laser performance in a spot-size converter integrated laser diode (SS-LD) with a pn-buried heterostructure (pn-BH) and demonstrate both the good coupling efficiency and high laser performance. We clarify that a high position and a high doping concentration of an n-InP current blocking layer in the pn-BH are favorable for high-coupling efficiency with a single-mode fiber by a two-dimensional (2-D) finite-element method-based calculation. By using the proposed concept, low-loss coupling of 1.6 dB with a low threshold current of 5.5 mA at room temperature and 19.6 mA even at 85 degrees C was achieved experimentally.