Abstract
Due to their tunable optical properties with various shapes, sizes, and compositions, nanowires (NWs) have been regarded as a class of semiconductor nanostructures with great potential for photodetectors, light-emitting diodes, gas sensors, microcavity lasers, optical modulators, and converters. Indium arsenide (InAs), an attractive III-V semiconductor NW with the advantages of narrow bandgap and large electron mobility, has attracted considerable interest in infrared optoelectronic and photonic devices. Here, we studied the ultrafast carrier dynamics and nonlinear optical responses of InAs NWs ranging from 1.0 to 2.8 μm and demonstrated the InAs-NW-based ultrafast broadband optical switch for passively Q-switching in all-solid-state laser systems. Furthermore, we achieved ultrafast optical modulation for laser mode-locking at 1.0 μm, paving the way for their applications in the field of ultrafast optics. These exotic optical properties indicate that InAs NWs have significant potential for various optoelectronic and photonic devices, especially in the mid-infrared wavelength range.
Highlights
I n the past two decades, nanomaterials have attracted enormous research interest due to their fascinating structure-dependent optical and electrical properties,[1−5] which have a significant impact on the realization of various photonic devices.[6−8] Due to their intrinsic quantum-confined one-dimensional (1D) structure, semiconductor nanowires (NWs) have been intensively studied as building blocks for the fabrication of nanoelectronic[9−11] and photonic[5,12,13] devices
III−V semiconductor NWs have been applied for various optoelectronic devices owing to large electron g-factors and small electron effective mass.[18−20] As the representative III−V
The positive ΔT/T0 signal reveals photobleaching signatures caused by Pauli blocking effects, which are induced by an excitation based on hot carrier dynamics
Summary
Absorption (saturable intensity and modulation depth) show the potential of InAs NWs for an application in optical switching with the operational wavelength up to 2.8 μm. The positive ΔT/T0 signal reveals photobleaching signatures caused by Pauli blocking effects, which are induced by an excitation based on hot carrier dynamics This indicates that InAs NWs exhibit a broadband saturable absorption effect in the wavelength band from 1.0 to 2.8 μm. To study the nonlinear optical absorption properties of InAs NWs, open-aperture Z-scan measurements were performed with excited lasers centered at wavelengths of 1.0, 2.0, and 2.8 μm. For a certain incident laser energy, the transmittance curve has a Gaussian-like shape that is symmetrical at the focus point (z = 0), which clearly shows the saturable absorption property of the InAs NWs. According to nonlinear optical theory, light attenuation during propagation in a nonlinear optical medium can be described as[34].
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