Monolithic integration of III-V coherent light sources on silicon (Si) photonic circuits has become an important route for cost-efficient and scalable on-chip photonic applications. To enable perfect position-control, high-density integration, and very flexible materials design, III-V semiconductor nanowires (NW) have emerged as unique nanoscale light sources with many advantageous properties. 

In this talk, we present our progress on epitaxially integrated III-V vertical-cavity NW lasers on Si and silicon-on-insulator (SOI) platform with emission wavelengths tuned from the near-infrared (NIR) to mid-infrared (MIR) spectral region. First, individual GaAs NW-lasers integrated by site-selective molecular beam epitaxy on planar Si substrate and non-planar Si ridge waveguides (WG) are shown with low lasing threshold down to ~20 µJ/cm² and high spontaneous emission (SE) factors (β~0.1-0.2) under optical pumping [1,2]. With numerical modelling, we further explore how the alternating refractive index of the SiO₂-masked Si WG influences the modal reflectivity and in-coupling efficiency of the NW laser with respect to geometrical parameters [3]. Consequently, we demon­strate direct coupling of lasing emission into Si WG-modes and mode propagation at central wavelength of ~820 nm, that is limited by absorption losses of the bulk GaAs gain material [2]. 

To surpass this, we further illustrate three different approaches that allow us to tailor the emission wavelengths into the Si transparency window towards the telecom O-band as well as the MIR-region. In particular, replacing the GaAs gain material by coaxial InGaAs multiple quantum wells (MQW) [4,5] as well as developing ternary GaAsSb NW-lasers [6,7] provide promising pathways for telecom-band lasers at elevated temperatures. Likewise, InAs NW-lasers emitting at wavelengths > 2µm are explored, which operate under continuous-wave (CW) excitation with high net optical gain [8].

 

[1] B. Mayer, et al., “Monolithically integrated high-b nanowire lasers on silicon”, Nano Letters 16, 152 (2016).

[2] T. Stettner, et al., “Direct coupling of coherent emission from site-selectively grown III-V nanowire lasers into proximal Si waveguides”, ACS Photonics 4, 2537 (2017).

[3] J. Bissinger, et al., “Optimized waveguide coupling of an integrated III-V nanowire laser on silicon”, J. Appl. Phys. 125, 243102 (2019).

[4] T. Stettner, et al., “Tuning lasing emission toward long wavelengths in GaAs-(In,Al)GaAs core-multishell nanowires, Nano Letters 18, 6292 (2018).

[5] P. Schmiedeke, et al., “Low-threshold strain-compensated InGaAs/(In,Al)GaAs multi-quantum well nanowire lasers emitting near 1.3 µm at room temperature, Appl. Phys. Lett. 118, 221103 (2021).

[6] P. Schmiedeke, et al., “Low-threshold single ternary GaAsSb nanowire lasers emitting at silicon transparent wavelengths”, Appl. Phys. Lett. 124, 071112 (2024).

[7] T. Schreitmüller, et al., “Large tolerance of lasing properties to impurity defects in GaAs(Sb)-AlGaAs core-shell nanowire lasers”, Adv. Funct. Mater. 34, 2311210 (2024).

[8] S. Meder, et al., “Continuous-wave mid-infrared lasing from single InAs nanowires grown on silicon”, under review (2024).