Advanced Organic and Polymer Whispering‐Gallery‐Mode Microresonators for Enhanced Nonlinear Optical Light

Abstract

Self‐assembled organic and polymer optical whispering‐gallery‐mode resonators (WGMRs) are emerging as a potential alternative to traditional inorganic resonators. In the beginning, this article presents a brief overview of the key parameters of interest in WGMRs and nonlinear optical properties. Later, recent results are surveyed demonstrating exciting properties of self‐assembled organic and polymer WGMRs of various shapes in the amplification of linear and nonlinear optical effects due to a strong light confinement associated with WGM excitation.

Ambient Pressure Sublimation Technique Provides Polymorph‐Selective Perylene Nonlinear Optical Microcavities

“…Optical excitation (objective: 150×; spot size: ≈0.8 µm) of a single α microcrystal edge with 405 nm continuous wave laser (see Figure 2B) and collection of the FL signal in the same point (confocal scheme, reflection geometry) showed optical resonances in the FL spectra (in the range of 470-735 nm) as numerous sharp peaks with very narrow spectral widths. [24] Similarly, experiments performed on the β phase crystal exhibited FL spectra with noticeable band maxima at about ≈485, 520, 555 nm (very weak) and 610 nm ( Figure 2N). A close look at emission band of α and β phase cavities illustrate that the 0-0 emission band at ≈487 nm is much weaker for the former cavity compared to the latter one.…”

“…It is expected that the square-and rhombus geometries of the perylene microcrystals might allow the circulation of FL photons due to four reflective edges and display the so-called whispering-gallery-mode (WGM) optical resonance in the FL spectrum. [24] Notably, the wavelength of the emitted WGM signals can also be fine-tuned by varying the size and geometries of the cavities. Further, the production of two-photon pumped NLO cavities is in demand because they produce frequency upconverted optical signals and importantly, operated by infrared lasers.…”

“…[22,23,[40][41][42][43][44] The prerequisites for an intrinsic type of NLO cavity are: (i) strong NLO activity (e.g., two-photon absorption) and (ii) high-quality microcrystal or structure with high refractive index and smooth lightreflecting mirror-like facets for an effective feedback action. [24] The latter criterion requires the growth of excellent quality organic crystal and is essential for the light storage efficiency of microcrystal-based nanophotonic devices.…”

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solid-state lasers (OSSLs), [7,8] organic field-effect transistors (OFETs), [9] organic light-emitting diodes (OLEDs), [10] and photovoltaic cells. [11,12] The semiconductor-based organic photonic devices are futuristic and have the potential to be employed in miniaturized nano photonic structures using microscale modules such as optical waveguides, [13][14][15][16] modulators, [17] filters, [18] cavities, [19][20][21][22][23][24] and optically [25][26][27] and electrically pumped lasers. [28][29][30] Perylene [31,32] and its derivatives are semiconductor organic materials used in optoelectronic and light-emitting devices industries.

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Quantum Dot Sensitized Whisperonic Solar Cells—Improving Efficiency Through Whispering Gallery Modes

“…Micron-sized spheres of SiO 2 , TiO 2 , Si 2 N 3 , SiC, polymethyl methacrylate, polystyrene, etc. have been used as optical cavities in optoelectronic sensing applications (Venkatakrishnarao et al, 2018). Total internal reflection at the cavity interface, where the refractive index of the cavity is greater than outside ambient, leads to the confinement and also helps in the sustainment of WGMs (Foreman et al, 2015).…”