Excitonic Lasing in Solution-Processed Subwavelength Nanosphere Assemblies

Appavoo, Kannatassen; Liu, Xiaoze; Menon, Vinod M.; Sfeir, Matthew Y.

doi:10.1021/acs.nanolett.5b05274

Cited by 12 publications

(11 citation statements)

References 41 publications

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“…Above a certain threshold, lasing is then observed. This kind of lasing, termed as random lasing, has been observed recently in ZnO nanostructures prepared on glass substrates by chemical bath deposition (CBD) method, also referred to as wet chemical method [2]- [4] and other simple methods such as sol gel and vapour phase techniques [5]- [7]. However, to realize electrically pumped random lasers, it is important to prepare the nanorods structure on a conductivity layer for electrical contacts.…”

Section: Introductionmentioning

confidence: 99%

Lasing from ZnO nanorods on ITO-coated substrates

Nordin

Priante

Shakfa

et al. 2018

Semiconductor Lasers and Laser Dynamics VIII

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Lasing was observed from ZnO nanorods prepared by a simple method of chemical bath deposition (CBD) on ITOcoated glass substrates. The X-ray diffraction pattern showed a dominant peak for (002) plane typical for good crystalline quality of ZnO grown in the z-direction with a wurtzite structure. Continuous-wave photoluminescence (PL) spectra revealed a peak centered at 380 nm corresponding to the band gap of ZnO. Under pulsed optical pumping, lasing was observed above the nominal PL peak, initially for one mode at 384 nm. Two additional modes at 386 nm and 390 nm was observed when the pumping power is further increased. Threshold was achieved at 0.7 µJ which was 10 times smaller than that reported for powder-based random lasers. In addition, gain pinning was also observed for the dominant mode and the additional two modes appeared upon onset of this gain pining behavior.

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Section: Introductionmentioning

confidence: 99%

Lasing from ZnO nanorods on ITO-coated substrates

Nordin

Priante

Shakfa

et al. 2018

Semiconductor Lasers and Laser Dynamics VIII

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“…[40,41] Furthermore, light-matter interaction was enhanced by the accumulated in-plane scattering following the emission process, while the loss rate was further minimized by reducing "voids" in the nanostructured complex medium. [34] Here, we highlight how critical the local dielectric environment is to the parameters of macroscopic lasing in our nanoscale complex medium. We perform ALD of dielectric material aluminum oxide or zinc oxide (denoted herein as Al 2 O x or ZnO x ) to infiltrate our complex medium at the nanoscale.…”

Section: Resultsmentioning

confidence: 99%

Large‐Area Lasing in Nanoscale Complex Media: The Critical Role of Local Dielectric Environment

Casey

Dhami

et al. 2022

Advanced Optical Materials

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Controlling how electromagnetic waves interact with complex media is critical for applications in imaging and focusing. Such lightwave interactions with complex media can lead to dramatic optical effects like lasing. While much work in random lasing focus on understanding how gain and scattering co‐operatively generate lasing, little work has focused on how to manipulate the lasing threshold without modifying the structural disorder. Here, a simple, mostly unexplored, strategy is demonstrated that employs atomic layer deposition (ALD) to tune the local near‐field environment while preserving the underpinning disorder—controlling lasing in a nanoscale complex medium on a large scale (>cm2). The nanoscale complex medium is a quasi‐2D system of coupled zinc oxide nanospheres with overall thickness deep in the sub‐wavelength regime (≈λ/4). Near‐ultraviolet femtosecond spectroscopy probes the broadband response of the gain nanomaterial, details how ALD process fundamentally modifies the fast‐picosecond and slow‐nanosecond carrier dynamics, and informs on the relevant timescales critical for lasing. Full‐field electromagnetic simulations provide critical insights about how near‐field dielectric environment modifies the nanostructure's scattering cross‐section, which ultimately results in enhanced lasing. These results highlight a simple path to control how electromagnetic waves interact in a complex medium, a key step toward large‐scale implementation of complex lasers.

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“…Importantly, a positive Δ T / T signal is also observed for wavelengths in the 380–400 nm range, which corresponds to the UV spectral region of the excitonic PL ( Figure 4 b,c). Such a positive signal can be attributed to stimulated emission (SE), suggesting the presence of net optical gain 45 in the material. Finally, a positive signal is also observed at longer wavelengths, up to 450 nm, and is attributed to a combination of PB and SE arising from ZnO surface states and defects.…”

Section: Resultsmentioning

confidence: 99%

Conformable Nanowire-in-Nanofiber Hybrids for Low-Threshold Optical Gain in the Ultraviolet

et al. 2020

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The miniaturization of diagnostic devices that exploit optical detection schemes requires the design of light-sources combining small size, high performance for effective excitation of chromophores, and mechanical flexibility for easy coupling to components with complex and non-planar shapes. Here, ZnO nanowire-in-fiber hybrids with internal architectural order are introduced, exhibiting a combination of polarized stimulated emission, low propagation losses of light modes, and structural flexibility. Ultrafast transient absorption experiments on the electrospun material show optical gain which gives rise to amplified spontaneous emission, with threshold lower than the value found in films. These systems are highly flexible and can conveniently conform to curved surfaces, which makes them appealing active elements for various device platforms, such as bendable lasers, optical networks and sensors, as well as for application in bioimaging, photo-crosslinking, and optogenetics.The development of miniaturized and effective light sources with emission in the near ultraviolet (UV) is highly important for all those fields, including microanalysis through fluorescence spectroscopy, chemical sensing, and healthcare diagnostics, where molecular photoexcitation is involved. 1-4 Together with mechanical flexibility to have them conformed to different surfaces or lodged within different lab-on-chip platforms, 2,3,5,6 UV-active materials are desired to feature stimulated emission and optical gain, which is the basic prerequisite to use them in compact laser systems and photonic networks. Examples of UV-emitters include various inorganics (GaN, ZnS, ZnO, etc.) and their nanostructures grown through chemical vapour transport processes, colloidal synthesis, and other deposition methods. 7-12 Inorganic nanostructures, and especially nanowires (NWs), have been largely exploited within semiconductor-embedding optical cavities, plasmonic nanolasers, and heterojunctions. 7,9,12,13 However, the so-obtained devices are largely limited to planar systems or substrates for nanostructure growth, they are mechanically stiff, and unconformable to curved surfaces.Polymeric light-emitting materials and films, 3,14-17 instead, can be easily coupled with bendable substrates and are more versatile in terms of configurational motifs, although their optical performance and stimulated emission properties are generally much less appealing and stable in time compared to inorganics.Hybrid approaches, inserting highly-efficient and stable oxide nanosystems in flexible polymer nanostructures and enabling high throughput processing, would combine advantages of UV lightemitting inorganics and plastic matrices, and potentially lead to materials with enhanced properties. For instance, in these systems light from UV nanoscale emitters could be efficiently coupled to polymer waveguides and transported along macroscale distances, 3,18 thus overcoming the high propagation losses typical of individual inorganic nanostructures 19 and enabling a much Published i...

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Excitonic Lasing in Solution-Processed Subwavelength Nanosphere Assemblies

Cited by 12 publications

References 41 publications

Lasing from ZnO nanorods on ITO-coated substrates

Lasing from ZnO nanorods on ITO-coated substrates

Large‐Area Lasing in Nanoscale Complex Media: The Critical Role of Local Dielectric Environment

Conformable Nanowire-in-Nanofiber Hybrids for Low-Threshold Optical Gain in the Ultraviolet

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