Photonic-Molecule Single-Mode Laser

Advanced Optical Materials

Yin

et al. 2017

role for the efficient intercavity coupling. However, the evanescent field is relatively weak in the reported photonic mole cules because most of the optical field is strongly confined within the coupled cavities (e.g., microdisks, [4,8,11,18] micro toroids, [19] microspheres, [3] microrods, [5,20] and microfibers [7] ). As such, one needs a deliberate control on both the cavity geometries and the intercavity coupling gap to ensure a good spectral match and efficient evanescent coupling between the coupled cavities. [18] Moreover, dynamic tuning of the intercavity coupling strength has been investigated in recent years, which were carried out by advanced and sophisticated techniques such as strain tuning, [21,22] acoustooptic control, [23] and precise micromanipulation techniques. [3] To extend and promote the research in the field of photonic molecules, it is of high interest to design novel photonic molecules extending from adjacent solid microcavities to thinwalled hollow cavities which possess intense evanescent field facilitating intercavity coupling and provide novel strategy for tuning of the coupling strength.Microtube cavities, which are formed by selfrolling of pre strained nanomembranes, feature unique properties such as hollowcore structures and ultrathin cavity walls (≈100-300 nm) for the study of lightmatter interactions and the integration of "labinatube" systems. [24][25][26][27] These key merits enable extensive applications ranging from optofluidic sensing, [28][29][30][31] single cell analysis, [32] dynamic molecular process detection, [33] photon plasmon coupling, [34] to optical spin-orbit coupling.[35] To combine with other media/objects, luminescent quantum dots, [36,37] quantum wells, [38] and organic molecules [39] have been enwrapped into the microtube wall by the rolling up process, which couple photoluminescence (PL) light to the microtube cavities to support whisperinggallery mode (WGM) resonances. [37,40] In this context, a design and demonstration of photonic molecule based on microtube cavity is of fundamental interest for the study of strong optical coupling and the promo tion of its potential applications.Herein, we report a novel design of photonic molecule by trapping a microsphere cavity into the hollow core of a rolled up microtube cavity. We focus on studying the WGM coupling between the trapped microsphere and microtube cavity with a significant difference of cavity sizes, which is in contrast to pre vious reports where the two externally adjacent microcavities possess highly similar sizes [11,12,41] or slightly mismatched sizes (less than two times). [4][5][6][7]18,[42][43][44] Periodic modulations on A photonic molecule formed by trapping a microsphere cavity into a hollow microtube cavity is demonstrated, which provides a novel design over conventional photonic molecules comprised of solid-core whispering gallery mode microcavities with externally tangent configuration. Periodic spectral modulations of mode intensity, resonant mode shift, and quality factor are observed...

Section: Resultsmentioning

confidence: 99%

Section: Strong Coupling In a Photonic Molecule Formed By Trapping A mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Strong Coupling in a Photonic Molecule Formed by Trapping a Microsphere in a Microtube Cavity

Advanced Optical Materials

Yin

et al. 2017

“…Photonic molecules (PhMs), which are composed of two or more coupled optical microcavities, such as whispering-gallery mode microcavities, Fabry-Perot microcavities, and point-defect microcavities in photonic crystal, have attracted broad attention and undergone intensive investigation since they were introduced [1][2][3]. An updated version of PhMs, plasmonic molecules (PMs) are metallic nanostructures where the individual plasmon modes interact strongly and show distinct collective behavior [4,5].…”

Section: Introductionmentioning

confidence: 99%

Symmetry-Breaking Effect on the Electromagnetic Properties of Plasmonic Trimers Composed of Graphene Nanodisks

et al. 2018

Plasmonic trimers composed of equal-sized graphene nanodisks are proposed in this paper. The symmetry-breaking effect on the electromagnetic properties of the nanostructure is numerically investigated by studying plasmon energy diagrams and optical scattering spectra in mid-infrared range with a gradient vertex angle. The degenerate plasmonic modes are lifted and new modes appear with increased vertex angle. The energy diagrams are consistent with scattering extinction spectra, about which the dipole moment distribution of the proposed structure is discussed to demonstrate the coupling strength of the collective plasmonic modes of the trimer. More specifically, the frequency tunability of the plasmonic trimer is pointed out by modifying the chemical potential of the graphene nanodisks without varying the geometric configuration. The proposed structure might find applications such as light-matter interaction, single molecule detection, and high-sensitivity chemical sensing.

Single Crystal Microrod Based Homonuclear Photonic Molecule Lasers

Sun

Advanced Optical Materials

et al. 2016

Autler-Townes splitting etc. [5] The active PMs have also shown great potentials in microlasers, nonlinear optics based optical switch, and experimentally exploring the mode coupling and exceptional points. [5][6][7][8][9][10][11][12] Very recently, PMs with unique properties such as parity-time symmetry, asymmetrical scattering have also been utilized to demonstrate the single-mode laser emission, [6] the optical chirality, [13] and the suppression or reviving of lasing modes. [7][8][9] Despite the rapid developments, most of these PMs are realized in size-mismatched microcavities with either Vernier or inversed Vernier effect. [14][15][16][17][18][19] The PMs with two or more identical cavities are extremely hard to be generated. This situation is simply caused by the unavoidable fabrication deviations, which are usually around hundreds of nanometers for standard photolithography and tens of nanometers for electron-beam lithography, respectively. Therefore, the experimental realization of homonuclear PMs at designed wavelength is strongly dependent on and actually hindered by the precise control of cavity size, separation distance, and refractive index. [20] In searching the techniques for homonuclear PMs, we turn to the bottom-up synthesized microstructures. [21] Compared with the top-down etched devices, the synthesized microstructures have several intrinsic advantages such as low cost and high crystal quality. The high crystal quality has been utilized to generate nanosized coherent light sources in a larger number of single crystal structures, such as ZnO, [22] GaN, [23] CdS, [24] and CdSe [25] microwire/nanowire, etc. Recently, a new class of hybrid organic-inorganic semiconductor, which is also known as hybrid lead halide perovskite, has attracted considerable research attention. [26][27][28][29][30][31][32] Owning to their ultralow defect density and long free carrier diffusion length, very low threshold and high quality (Q) factor laser emissions have been achieved in lead halide perovskite nanowires at the wavelength ranging from ultraviolet to near infrared. In 2016, the whispering-gallery-mode (WGM) transverse lasers in lead halide perovskite microrods have also been studied to achieve record high Q factors. [33,34] Most importantly, the synthesized microrods have naturally flat and highly uniform side facets. Consequently, they have been used as natural platforms for high-density and uniform nanolaser array and other devices. [35,36] However, the great potentials are still far from being well developed. Here, Homonuclear photonic molecules are essential platforms to tailor and manipulate light in micro-and nanoscales. While photonic molecule microlasers have been widely explored in the past two decades, the unavoidable fabrication deviations make their resonant units hard to be identical and, thus, the corresponding practical applications are hindered by the experimental realization. Herein, the authors experimentally demonstrate a novel and effective approach to achieve homonuclear photonic molecul...