$\mathbf{1545}\ \mu \mathbf{m}$ Quantum Dot Vertical Cavity Surface Emitting Laser with low threshold

In this work, we report on the first room temperature quantum dot (QD) vertical cavity surface emitting laser(VCSEL) operating at 1545 nm on InP substrate. QD growth has been first studied to optimize the QD density and wavelength for an operation at 1520 nm. High photoluminescence efficiency and low linewedth (125 nm) is obtained on a 5 stacked structure. The VCSEL gain structure is composed of three groups of five QD layers grown on InP(311)B, inserted in a microcavity defined by full dielectric bragg mirrors. Continuous wave operation is demonstrated under optical excitation. QD VCSEL threshold is as low as 1.5 mW, a value 5 to 6 times smaller compared with our previous best VCSEL structures, integrating strained quantum wells based VCSEL with similar design.