HIGH-COUPLING EFFICIENCY OF A 1.3-MU-M SPOT-SIZE CONVERTER INTEGRATEDLASER-DIODE WITH PN-BURIED HETEROSTRUCTURE FOR HIGH-TEMPERATURE OPERATION

We propose a novel design concept for low-loss coupling with high lase r 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 hig h position and a high doping concentration of an n-InP current blockin g 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-ba sed 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 1 9.6 mA even at 85 degrees C was achieved experimentally.