Inverse design of two-dimensional disordered structures for spectral optimization of random lasers

Okamoto, Takashi; Imamura, K.; Kajisa, Kouki

doi:10.1016/j.optcom.2021.127775

Cited by 7 publications

(6 citation statements)

References 30 publications

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“…RL emission performance of HNT1 and HNT2 is expected to be identical because of their similar linear optical properties around ∼600 nm. Anyway, inhomogeneity in the distribution of the scatterer may lead to a slight improvement in the P in Th , − as we have observed for HNT1-RhB.…”

Section: Resultssupporting

confidence: 52%

Naturally Occurring Halloysite Nanotubes as Light Scatterers for Stable Random Lasing Applications

Pramanik,

Sciortino,

Reale

et al. 2023

ACS Appl. Nano Mater.

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Naturally occurring halloysite nanotubes (HNTs) have attracted significant scientific interest due to their multifunctional behavior and biocompatibility. However, the application of HNTs in photonics is still unexplored. Here, natural HNTs with different lengths and diameters have been employed as passive scatterers for the generation of random laser (RL) emission from rhodamine B (RhB) in a colloidal phase. Upon pumping at 532 nm, mixed HNT-RhB disordered colloidal systems are shown to yield orange RL emission with a linewidth as small as ∼4 nm. Moreover, a statistical analysis of shot-to-shot correlations among RL modes reveals an obvious photonic paramagnetic to spin-glass transition with increasing pump energy, which is a unique statistical fingerprint of RL. Interestingly, besides acting as scatterers, the HNTs are also found to improve the photostability of RhB molecules. Indeed, HNTs help to better dissipate the excess energy deposited in the gain medium, thus protecting the dye from photodegradation and facilitating the achievement of RL. The results contribute to the theoretical understanding and technical development of low-cost RL devices based on widely available sources in view of multiple prospective applications in photonics.

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Section: Resultssupporting

confidence: 52%

Naturally Occurring Halloysite Nanotubes as Light Scatterers for Stable Random Lasing Applications

Pramanik,

Sciortino,

Reale

et al. 2023

ACS Appl. Nano Mater.

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“…It needs to provide sufficient optical gain to surpass losses and reach the lasing threshold. 37 This condition was achieved as shown in Figure 1c−f, wherein the optical gain became stronger than the loss when the power density increased near the threshold. This process stimulated the emission and resulted in the emergence of RYGB color.…”

Section: Resultsmentioning

confidence: 81%

“…The random laser medium is fundamental in recognizing a specified spectrum of emitted light. It needs to provide sufficient optical gain to surpass losses and reach the lasing threshold . This condition was achieved as shown in Figure c–f, wherein the optical gain became stronger than the loss when the power density increased near the threshold.…”

Section: Resultsmentioning

confidence: 99%

Speckle-Free, Angle-Free, Cavity-Free White Laser with a High Color Rendering Index

Hou,

Tsui,

Chou

et al. 2024

ACS Appl. Mater. Interfaces

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The freedom from efficiency droop motivates monochromatic lasers to progress in general lighting applications due to the demand for more efficient and sustainable light sources. Still, a white light based on monochromatic lasers with high lighting quality, such as a high color rendering ability, an angle-independent output, and a speckle-free illumination, has not yet been fabricated nor demonstrated. Random lasers, with the special mechanism caused by multiple scattering, the angle-free emission, and the uncomplicated fabrication processes, inspire us to investigate the feasibility of utilizing them in general lighting. In this work, a white random laser with a high color rendering index (CRI) value, regardless of pumping energy and observing direction, was performed and discussed. We also investigated the stability of white RL as its CIE chromaticity coordinates exhibit negligible differences with increasing pump energy density, retaining its high-CRI measurement. Also, it exhibits angleindependent emission while having a high color rendering ability. After passing through a scattering film, it generated no speckles compared to the conventional laser. We demonstrated the advances in white laser illumination, showing that a white random laser is promising to be applied for high-brightness illumination, biological-friendly lighting, accurate color selections, and medical sensing.

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“…The typical algorithm is direct binary search (DBS) [12]. The DBS method enables optimization of a two-dimensional (2D) structure as a checkerboard pattern [13], and involves iteratively modifying the pattern by switching the state of individual pixels between two possible values, while evaluating the resulting optical performance. Since the doping profile covering the rib cross-section in the silicon modulator is also a 2D pattern, the same idea of inverse design can be applied to the search for optimal doping profiles.…”

Section: Methodsmentioning

confidence: 99%

PSO-Aided Inverse Design of Silicon Modulator

Zhu,

Zhao,

Sheng

et al. 2024

IEEE Photonics J.

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Optimizing doping profiles has always been a key approach to enhance the performance of silicon modulators. Nevertheless, the pursuit of innovative profiles has encountered barriers in recent times. To tackle this issue, the idea of inverse design, widely adopted in passive photonic devices, can be employed in silicon active devices. As a result, we incorporate the inverse design method with the particle swarm optimization (PSO) algorithm and achieve a G-shaped doping profile for the modulator, exhibiting superior VπL of 0.68 V•cm and low loss of 9.3 dB/cm. The small-signal frequency response suggests a reliable operation range under reverse biases of 1∼3 V with the bandwidth over 26 GHz. The silicon modulator with a Gshaped design demonstrates remarkable efficiency in modulation and very low loss, suggesting its great potential for application in microwave front-end systems. The use of inverse design shows great potential in enhancing active silicon photonic devices, allowing for faster, higher-capacity, and more reliable data communication systems.

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Inverse design of two-dimensional disordered structures for spectral optimization of random lasers

Cited by 7 publications

References 30 publications

Naturally Occurring Halloysite Nanotubes as Light Scatterers for Stable Random Lasing Applications

Naturally Occurring Halloysite Nanotubes as Light Scatterers for Stable Random Lasing Applications

Speckle-Free, Angle-Free, Cavity-Free White Laser with a High Color Rendering Index

PSO-Aided Inverse Design of Silicon Modulator

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