Low-threshold index-guided 1.5 μm long-wavelength vertical-cavity surface-emitting laser with high efficiency

A significantly improved InP-based vertical-cavity surface-emitting laser with record device performance is demonstrated. Utilizing a twofold epitaxial growth process, self-adjusted lateral current confinement and index guiding are accomplished by means of a buried InGa(Al)As tunnel junction. Front and back mirrors are realized by 35 epitaxial InGaAlAs/InAlAs layer pairs and a $\text{1.5\hspace{0.05em}}{\mathrm{MgF}}_{\mathrm{2}}\mathrm{/a-}\mathrm{Si}$ layer pair, respectively. At room temperature and under continuous wave condition, lasers with small aperture diameters of only 13 μm exhibit record output powers of 1.6 mW with quantum efficiencies around 25%. For these devices, threshold current and voltage are as low as 4 mA and 1.2 V, respectively, because of low series resistances around 70 Ω.