Highly compact, filter-free multispectral photodetectors have important applications in biological imaging, face recognition, and remote sensing. In this work, we demonstrate room-temperature wavelength-selective multipixel photodetectors based on GaAs 0.94 Sb 0.06 nanowire arrays grown by metalorganic vapor phase epitaxy, providing more than 10 light detection channels covering both visible and near-infrared ranges without using any optical filters. The nanowire array geometry-related tunable spectral photoresponse has been demonstrated both theoretically and experimentally and shown to be originated from the strong and tunable resonance modes that are supported in the GaAsSb array nanowires. High responsivity and detectivity (up to 44.9 A/W and 1.2 × 10 12 cm √Hz/W at 1 V, respectively) were obtained from the array photodetectors, enabling highresolution RGB color imaging by applying such a nanowire array based single pixel imager. The results indicate that our filter-free wavelength-selective GaAsSb nanowire array photodetectors are promising candidates for the development of future high-quality multispectral imagers.

Dielectric metasurfaces made of high refractive index and low optical loss materials have emerged as promising platforms to achieve high-quality factor modes enabling strong light–matter interaction. Bound states in the continuum have shown potential to demonstrate narrow spectral resonances but often require asymmetric geometry and typically feature strong polarization dependence, complicating fabrication and limiting practical applications. We introduce a novel approach for designing high-quality bound states in the continuum using magnetic dipole resonances coupled to a mirror. The resulting metasurface has simple geometric parameters requiring no broken symmetry. To demonstrate the unique features of our photonic platform we show a record-breaking third harmonic generation efficiency from the metasurface benefiting from the strongly enhanced electric field at high-quality resonances. Our approach mitigates the shortcomings of previous platforms with simple geometry enabling facile and large-area fabrication of metasurfaces paving the way for applications in optical sensing, detection, quantum photonics, and nonlinear devices.

The modern commercial optoelectronic infrastructure rests on a foundation of only a few, select semiconductor materials, capable of serving as viable substrates for devices. Any new active device, to have any hope of moving past the laboratory setting, must demonstrate compatibility with these substrate materials. Across much of the electromagnetic spectrum, this simple fact has guided the development of lasers, photodetectors, and other optoelectronic devices. In this work, we propose and demonstrate the concept of a multi-functional metamorphic buffer (MFMB) layer that not only allows for growth of highly lattice-mismatched active regions on InP substrates but also serves as a bottom cladding layer for optical confinement in a laser waveguide. Using the MFMB concept in conjunction with a strain-balanced multiple quantum well active region, we demonstrate laser diodes operating at room temperature in the technologically vital, and currently underserved, 2.5–3.0 μm wavelength range.

The measurement of minority carrier lifetimes is vital to determining the material quality and operational bandwidth of a broad range of optoelectronic devices. Typically, these measurements are made by recording the temporal decay of a carrier-concentration-dependent material property following pulsed optical excitation. Such approaches require some combination of efficient emission from the material under test, specialized collection optics, large sample areas, spatially uniform excitation, and/or the fabrication of ohmic contacts, depending on the technique used. In contrast, here we introduce a technique that provides electrical readout of minority carrier lifetimes using a passive microwave resonator circuit. We demonstrate >10 5 improvement in sensitivity, compared with traditional photoemission decay experiments and the ability to measure carrier dynamics in micron-scale volumes, much smaller than is possible with other techniques. The approach presented is applicable to a wide range of 2D, micro-, or nano-scaled materials, as well as weak emitters or non-radiative materials.

Type-II In(Ga)Sb quantum-confined structures in InAs matrices offer a potential material system for wavelength flexible, high-efficiency, surface-emitting mid-infrared sources. In this work, the authors investigate the carrier dynamics in this material system and demonstrate a number of techniques for engineering carrier lifetimes in such emitters. Samples are grown by molecular beam epitaxy and optically characterized using temperature dependent Fourier transform infrared spectroscopy and mid-infrared time-resolved photoluminescence. The authors investigate both In(Ga)Sb quantum wells and quantum dots, and demonstrate significant improvements in isolated quantum well emitter carrier lifetimes by controlling quantization in the conduction band, or alternatively, by the formation of InGaSb quantum dot structures in InAs matrices. The authors correlate the engineered improvement in carrier lifetime with the emitters temperature performance of our emitters.