High Power Single Mode 1300-nm Superlattice Based VCSEL: Impact of the Buried Tunnel Junction Diameter on Performance
S. A. Blokhin, A. V. Babichev, A. G. Gladyshev, L. Ya. Karachinsky, I. I. Novikov, A. A. Blokhin, M. A. Bobrov, N. A. Maleev, V. V. Andryushkin, Dmitrii V. Denisov, K. O. Voropaev, I. O. Zhumaeva, V. M. Ustinov, A. Yu. Egorov, N. N. Ledentsov
Abstract
High power single mode wafer-fused 1300-nm VCSELs with a gain region based on InGaAs/InAlGaAs short period superlattice are fabricated. An InP-based optical cavity and two AlGaAs/GaAs distributed Bragg reflector heterostructures were grown by molecular beam epitaõy. The current and optical confinement is provided by a lateral-structured buried tunnel junction with etching depth of <inline-formula> <tex-math notation="LaTeX">$\sim 25$ </tex-math></inline-formula> nm. It is shown that optimal diameter of the buried tunnel junction for high-power single mode emission is <inline-formula> <tex-math notation="LaTeX">$\sim 5$ </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">$6~\mu \text{m}$ </tex-math></inline-formula>. The VCSEL demonstrates more than 6 mW single mode continuous-wave power and a threshold current less than 1.5 mA at 20 °C. The output optical power exceeds 1 mW at 85 °C. A -3dB modulation bandwidth up to 8 GHz and 6 GHz is obtained at 20 °C and 85 °C, respectively. The gain coefficient of <inline-formula> <tex-math notation="LaTeX">$\sim 650$ </tex-math></inline-formula> cm<sup>−1</sup> and the transparency current density of <inline-formula> <tex-math notation="LaTeX">$\sim 630$ </tex-math></inline-formula> A/cm<sup>2</sup> are estimated at zero gain-to-cavity detuning (\sim 60 °C). The ultimate low internal optical losses about 0.08 % per round-trip (distributed losses ~3.2 cm<sup>−1</sup>) at 20 °C and 0.13 % per round-trip (distributed losses ~5.5 cm<sup>−1</sup>) at 100 °C were obtained.