Abstract
Optical feedback mechanisms are often obtained from well-defined resonator structures fabricated by top-down processes. Here, we demonstrate that two-dimensional networks of metallic nanowires dispersed on the semiconductor slab can provide strong in-plane optical feedback and, thus, form randomly-distributed Fabry-Pérot-type resonators that can achieve multi- or single-mode lasing action in the near infrared wavelengths. Albeit with their subwavelength-scale cross-sections and uncontrolled inter-nanowire distances, a cluster of nearly parallel metal nanowires acts as an effective in-situ reflector for the semiconductor-metal slab waveguide modes for coherent optical feedback in the lateral direction. Fabry-Pérot type resonance can be readily developed by a pair of such clusters coincidentally formed in the solution-processed random nanowire network. Our low-cost and large-area approach for opportunistic random cavity formation would open a new pathway for integrated planar light sources for low-coherence imaging and sensing applications.
Highlights
Optical feedback mechanisms are often obtained from well-defined resonator structures fabricated by top-down processes
Conventional semiconductor-based lasers with well-defined optical resonator structures are typically obtained from top-down or subtractive fabrication processes, including multiple growth, lithography and/or etching steps, to unambiguously define the laser cavity boundary by refractive index contrasts
We find that the TE-polarized modes show significantly higher reflectance than the transverse magnetic (TM) modes because the metal nanowire orientation matches with the electric field oscillation direction
Summary
Optical feedback mechanisms are often obtained from well-defined resonator structures fabricated by top-down processes. We demonstrate that two-dimensional networks of metallic nanowires dispersed on the semiconductor slab can provide strong in-plane optical feedback and, form randomly-distributed Fabry-Pérot-type resonators that can achieve multi- or single-mode lasing action in the near infrared wavelengths. Albeit with their subwavelength-scale cross-sections and uncontrolled inter-nanowire distances, a cluster of nearly parallel metal nanowires acts as an effective in-situ reflector for the semiconductor-metal slab waveguide modes for coherent optical feedback in the lateral direction. Conventional semiconductor-based lasers with well-defined optical resonator structures are typically obtained from top-down or subtractive fabrication processes, including multiple growth, lithography and/or etching steps, to unambiguously define the laser cavity boundary by refractive index contrasts. One-dimensional metal nanowires are an excellent candidate in this context since they strongly interact with the electromagnetic waves and have been studied for plasmonic resonators[12,13,14] and waveguides[15,16,17]
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