Indium arsenide phosphide (InAsP) nanowires (NWs), a member of the III–V semiconductor family, have been used in various photonic and optoelectronic applications thanks to their unique electrical and optical properties such as high carrier mobility and adjustable band gap. In this work, we synthesize InAsP NWs and further explore their nonlinear optical properties. The ultrafast carrier dynamics and nonlinear optical response are thoroughly studied based on the nondegenerate pump probe and Z-scan experimental measurements. Two different characteristic carrier lifetimes (∼2 and ∼15ps) from InAsP NWs are observed during the excited-carrier relaxation process. Based on the physical model analysis, the relaxation process can be ascribed to the carrier cooling process via carrier-phonon scattering and Auger recombination. In addition, based on the measured excited-carrier lifetime and Pauli-blocking principle, we discover that InAsP NWs show strong saturable absorption properties at the wavelengths of 532 and 1064 nm. Last, we demonstrate for the first time a femtosecond (∼426fs) solid-state laser based on an InAsP NWs saturable absorber at 1.04 μm. We believe that our work provides a better understanding of the InAsP NWs optical properties and will further advance their photonic applications in the near-infrared range.

We report an indium phosphide nanowire (NW)-induced cavity in a silicon planar photonic crystal (PPC) waveguide to improve the light–NW coupling. The integration of NW shifts the transmission band of the PPC waveguide into the mode gap of the bare waveguide, which gives rise to a microcavity located on the NW section. Resonant modes with Q factors exceeding 103 are obtained. Leveraging on the high density of the electric field in the microcavity, the light–NW interaction is enhanced strongly for efficient nonlinear frequency conversion. Second-harmonic generation and sum-frequency generation in the NW are realized with a continuous-wave pump laser in a power level of tens of microwatts, showing a cavity-enhancement factor of 112. The hybrid integration structure of NW-PPC waveguide and the self-formed microcavity not only opens a simple strategy to effectively enhance light–NW interactions, but also provides a compact platform to construct NW-based on-chip active devices.

Indium phosphide (InP) nanowires (NWs) have attracted significant attention due to their exotic properties that are different from the bulk counterparts, and have been widely used for light generation, amplification, detection, modulation, and switching, etc. Here, high-quality InP NWs were directly grown on a quartz substrate by the Au-nanoparticle assisted vapor-liquid-solid method. We thoroughly studied their nonlinear optical absorption properties at 1.06 μm by the open-aperture Z-scan method. Interestingly, a transition phenomenon from saturable absorption (SA) to reverse saturable absorption (RSA) was observed with the increase of the incident laser intensity. In the analysis, we found that the effective nonlinear absorption coefficient (βeff～?102cm/MW) under the SA process was 3 orders of magnitude larger than that during the RSA processes. Furthermore, the SA properties of InP NWs were experimentally verified by using them as a saturable absorber for a passively Q-switched Nd:YVO4 solid-state laser at 1.06 μm, where the shortest pulse width of 462 ns and largest single pulse energy of 1.32 μJ were obtained. Moreover, the ultrafast carrier relaxation dynamics were basically studied, and the intra-band and inter-band ultrafast carrier relaxation times of 8.1 and 63.8 ps, respectively, were measured by a degenerate pump–probe method with the probe laser of 800 nm. These results well demonstrate the nonlinear optical absorption properties, which show the excellent light manipulating capabilities of InP NWs and pave a way for their applications in ultrafast nanophotonic devices.

The position-dependent mode couplings between a semiconductor nanowire (NW) and a planar photonic crystal (PPC) nanocavity are studied. By scanning an NW across a PPC nanocavity along the hexagonal lattice’s Γ – M and M – K directions, the variations of resonant wavelengths, quality factors, and mode volumes in both fundamental and second-order resonant modes are calculated, implying optimal configurations for strong mode-NW couplings and light-NW interactions. For the fundamental (second-order) resonant mode, scanning an NW along the M – K (Γ – M) direction is preferred, which supports stronger light-NW interactions with larger NW-position tolerances and higher quality factors simultaneously. The simulation results are confirmed experimentally with good agreements.