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Amr S Helmy - One of the best experts on this subject based on the ideXlab platform.

  • asymmetric long range hybrid plasmonic modes in asymmetric nanometer scale structures
    Journal of The Optical Society of America B-optical Physics, 2014
    Co-Authors: Amr S Helmy
    Abstract:

    The structural symmetry required for long-range surface-plasmon-polariton modes to take place is examined and mapped to asymmetric plasmonic structures. This study leads to a design methodology that facilitates the realization through systematic design of long-range modes in any asymmetric hybrid plasmonic waveguide (AHPW). Examining the modal behavior of an AHPW reveals that field symmetry on either side of the metal is the only necessary condition for plasmonic structures to support long-range propagation. We report that this field symmetry condition can be satisfied irrespective of asymmetry in a waveguide structure, material, or even field profile. The structure is analyzed using the coupled mode theory, transfer matrix method, and finite-difference time-domain method. The AHPW supports high-loss antisymmetric and long-range symmetric Supermodes. Dispersion of these Supermodes with respect to waveguide dimensions display similar anticrossing characteristics to those obtained in two coupled harmonic oscillators, where the propagation losses display peaks and troughs in the vicinity of the anticrossing region. To place the work in perspective, an AHPW with a width of 200 nm was found to support a long-range supermode with a subwavelength mode area of 0.23  μm2 and propagation loss of 0.025  dB·μm−1 at the wavelength of 1550 nm, providing a radically improved attenuation confinement trade-off compared with other common types of plasmonic waveguides.

  • Asymmetric long-range hybrid-plasmonic modes in asymmetric nanometer-scale structures
    2014
    Co-Authors: Amr S Helmy
    Abstract:

    The structural symmetry required for long-range surface-plasmon-polariton modes to take place is examined and mapped to asymmetric plasmonic structures. This study leads to a design methodology that facilitates the reali-zation through systematic design of long-range modes in any asymmetric hybrid plasmonic waveguide (AHPW). Examining the modal behavior of an AHPW reveals that field symmetry on either side of the metal is the only necessary condition for plasmonic structures to support long-range propagation. We report that this field sym-metry condition can be satisfied irrespective of asymmetry in a waveguide structure, material, or even field profile. The structure is analyzed using the coupled mode theory, transfer matrix method, and finite-difference time-domain method. The AHPW supports high-loss antisymmetric and long-range symmetric Supermodes. Dispersion of these Supermodes with respect to waveguide dimensions display similar anticrossing characteristics to those obtained in two coupled harmonic oscillators, where the propagation losses display peaks and troughs in the vicinity of the anticrossing region. To place the work in perspective, an AHPWwith a width of 200 nm was found to support a long-range supermode with a subwavelength mode area of 0.23 μm2 and propagation loss of 0.025 dB · μm−1 at the wavelength of 1550 nm, providing a radically improved attenuation confinement trade-off compared with other common types of plasmonic waveguides. © 2014 Optical Society of Americ

Zihe Gao - One of the best experts on this subject based on the ideXlab platform.

  • complex coupling coefficient in laterally coupled microcavity laser diode arrays
    Applied Physics Letters, 2020
    Co-Authors: Harshil Dave, Zihe Gao, Kent D Choquette
    Abstract:

    The complex component of the coupling coefficient κ = κ r + i κ i, used to describe the coupling between adjacent semiconductor microcavity laser diodes, is studied. The complex component κ i represents the gain or loss difference between the coherent in-phase and out-of-phase array Supermodes obtained from two laterally coupled lasers. Steady-state analysis reveals that the threshold of the preferred coherent supermode is lower than that of an individual laser mode in proportion to κ i. We show that the complex component κ i can be experimentally extracted from a simple output power vs current measurement. Furthermore, the change in the lasing threshold at the onset of optical coupling perturbs the differential resistance of the coupled lasers. Therefore, an electrical signature of optical coupling can be detected in the diode array series resistance.

  • exceptional point behavior of non hermitian microcavity laser arrays
    OSA Advanced Photonics Congress (AP) 2020 (IPR NP NOMA Networks PVLED PSC SPPCom SOF) (2020) paper NpW2E.5, 2020
    Co-Authors: Harshil Dave, Zihe Gao, Kent D Choquette
    Abstract:

    Coherently coupled 2-element laser diode arrays near the modal exceptional point have equal photon-photon and carrier-photon resonances with indistinguishable Supermodes. Experimentally the relative intensity noise is suppressed near the exceptional point.

  • mode engineering in linear coherently coupled vertical cavity surface emitting laser arrays
    IEEE Journal of Selected Topics in Quantum Electronics, 2019
    Co-Authors: Bradley J. Thompson, Zihe Gao
    Abstract:

    The supermode tuning of coherent 3 × 1 vertical-cavity surface-emitting laser arrays are characterized and simulated. The array elements are resonantly tuned to achieve coherent operation using selective current injection. Depending on the electrical bias, multiple coherent Supermodes are observed above threshold. An effective index model is developed to account for the variable current injection and to simulate the Supermodes of the linear array. Agreement between experimental near-field and far-field coherent modes and our model simulations are found both at and above lasing threshold.

  • non hermiticity and exceptional points in coherently coupled vertical cavity laser diode arrays
    Applied Physics Letters, 2019
    Co-Authors: Zihe Gao, Bradley J. Thompson, Harshil Dave, Stewart T M Fryslie, Kent D Choquette
    Abstract:

    Coherently coupled laser arrays can be described by the temporal coupled mode theory in which the array modal behavior can be classified according to the coupling matrix, M¯¯. Accounting for a nonuniform gain/loss distribution in a laser array makes M¯¯ a non-Hermitian matrix, and experimentally we find phase-front tuning (beam steering) of the coherent supermode as a result of the non-Hermiticity. We report the experimental characterization of the Supermodes in coherently coupled vertical cavity surface emitting laser diode arrays and demonstrate control of non-Hermiticity by spatially varying injection currents. Exceptional points are identified in these electrically injected microcavity diode arrays.Coherently coupled laser arrays can be described by the temporal coupled mode theory in which the array modal behavior can be classified according to the coupling matrix, M¯¯. Accounting for a nonuniform gain/loss distribution in a laser array makes M¯¯ a non-Hermitian matrix, and experimentally we find phase-front tuning (beam steering) of the coherent supermode as a result of the non-Hermiticity. We report the experimental characterization of the Supermodes in coherently coupled vertical cavity surface emitting laser diode arrays and demonstrate control of non-Hermiticity by spatially varying injection currents. Exceptional points are identified in these electrically injected microcavity diode arrays.

Kent D Choquette - One of the best experts on this subject based on the ideXlab platform.

  • complex coupling coefficient in laterally coupled microcavity laser diode arrays
    Applied Physics Letters, 2020
    Co-Authors: Harshil Dave, Zihe Gao, Kent D Choquette
    Abstract:

    The complex component of the coupling coefficient κ = κ r + i κ i, used to describe the coupling between adjacent semiconductor microcavity laser diodes, is studied. The complex component κ i represents the gain or loss difference between the coherent in-phase and out-of-phase array Supermodes obtained from two laterally coupled lasers. Steady-state analysis reveals that the threshold of the preferred coherent supermode is lower than that of an individual laser mode in proportion to κ i. We show that the complex component κ i can be experimentally extracted from a simple output power vs current measurement. Furthermore, the change in the lasing threshold at the onset of optical coupling perturbs the differential resistance of the coupled lasers. Therefore, an electrical signature of optical coupling can be detected in the diode array series resistance.

  • exceptional point behavior of non hermitian microcavity laser arrays
    OSA Advanced Photonics Congress (AP) 2020 (IPR NP NOMA Networks PVLED PSC SPPCom SOF) (2020) paper NpW2E.5, 2020
    Co-Authors: Harshil Dave, Zihe Gao, Kent D Choquette
    Abstract:

    Coherently coupled 2-element laser diode arrays near the modal exceptional point have equal photon-photon and carrier-photon resonances with indistinguishable Supermodes. Experimentally the relative intensity noise is suppressed near the exceptional point.

  • non hermiticity and exceptional points in coherently coupled vertical cavity laser diode arrays
    Applied Physics Letters, 2019
    Co-Authors: Zihe Gao, Bradley J. Thompson, Harshil Dave, Stewart T M Fryslie, Kent D Choquette
    Abstract:

    Coherently coupled laser arrays can be described by the temporal coupled mode theory in which the array modal behavior can be classified according to the coupling matrix, M¯¯. Accounting for a nonuniform gain/loss distribution in a laser array makes M¯¯ a non-Hermitian matrix, and experimentally we find phase-front tuning (beam steering) of the coherent supermode as a result of the non-Hermiticity. We report the experimental characterization of the Supermodes in coherently coupled vertical cavity surface emitting laser diode arrays and demonstrate control of non-Hermiticity by spatially varying injection currents. Exceptional points are identified in these electrically injected microcavity diode arrays.Coherently coupled laser arrays can be described by the temporal coupled mode theory in which the array modal behavior can be classified according to the coupling matrix, M¯¯. Accounting for a nonuniform gain/loss distribution in a laser array makes M¯¯ a non-Hermitian matrix, and experimentally we find phase-front tuning (beam steering) of the coherent supermode as a result of the non-Hermiticity. We report the experimental characterization of the Supermodes in coherently coupled vertical cavity surface emitting laser diode arrays and demonstrate control of non-Hermiticity by spatially varying injection currents. Exceptional points are identified in these electrically injected microcavity diode arrays.

Nasser Peyghambarian - One of the best experts on this subject based on the ideXlab platform.

Oskar Painter - One of the best experts on this subject based on the ideXlab platform.

  • design of a quasi 2d photonic crystal optomechanical cavity with tunable large x 2 coupling
    Optics Express, 2016
    Co-Authors: Mahmoud Kalaee, T K Paraiso, Hannes Pfeifer, Oskar Painter
    Abstract:

    We present the optical and mechanical design of a mechanically compliant quasi-two-dimensional photonic crystal cavity formed from thin-film silicon in which a pair of linear nanoscale slots are used to create two coupled high-Q optical resonances. The optical cavity Supermodes, whose frequencies are designed to lie in the 1500 nm wavelength band, are shown to interact strongly with mechanical resonances of the structure whose frequencies range from a few MHz to a few GHz. Depending upon the symmetry of the mechanical modes and the symmetry of the slot sizes, we show that the optomechanical coupling between the optical Supermodes can be either linear or quadratic in the mechanical displacement amplitude. Tuning of the nanoscale slot size is also shown to adjust the magnitude and sign of the cavity supermode splitting 2J, enabling near-resonant motional scattering between the two optical Supermodes and greatly enhancing the x^2-coupling strength. Specifically, for the fundamental flexural mode of the central nanobeam of the structure at 10 MHz the per-phonon linear cross-mode coupling rate is calculated to be be g+−/2π=1MHz, corresponding to a per-phonon x^2-coupling rate of g′/2π=1kHz for a mode splitting 2J/2π = 1 GHz which is greater than the radiation-limited supermode linewidths.

  • position squared coupling in a tunable photonic crystal optomechanical cavity
    Physical Review X, 2015
    Co-Authors: T K Paraiso, Mahmoud Kalaee, L Y Zang, Hannes Pfeifer, Florian Marquardt, Oskar Painter
    Abstract:

    We present the design, fabrication, and characterization of a planar silicon photonic crystal cavity in which large position-squared optomechanical coupling is realized. The device consists of a double-slotted photonic crystal structure in which motion of a central beam mode couples to two high-Q optical modes localized around each slot. Electrostatic tuning of the structure is used to controllably hybridize the optical modes into Supermodes that couple in a quadratic fashion to the motion of the beam. From independent measurements of the anticrossing of the optical modes and of the dynamic optical spring effect, a position-squared vacuum coupling rate as large as g'/2π=245  Hz is inferred between the optical Supermodes and the fundamental in-plane mechanical resonance of the structure at ω_m/2π=8.7  MHz, which in displacement units corresponds to a coupling coefficient of g'/2π=1  THz/nm 2. For larger supermode splittings, selective excitation of the individual optical Supermodes is used to demonstrate optical trapping of the mechanical resonator with measured g'/2π=46  Hz.

  • Position-Squared Coupling in a Tunable Photonic Crystal Optomechanical Cavity
    American Physical Society, 2015
    Co-Authors: T K Paraiso, Mahmoud Kalaee, Hannes Pfeifer, Florian Marquardt, Leyun Zang, Oskar Painter
    Abstract:

    We present the design, fabrication, and characterization of a planar silicon photonic crystal cavity in which large position-squared optomechanical coupling is realized. The device consists of a double-slotted photonic crystal structure in which motion of a central beam mode couples to two high-Q optical modes localized around each slot. Electrostatic tuning of the structure is used to controllably hybridize the optical modes into Supermodes that couple in a quadratic fashion to the motion of the beam. From independent measurements of the anticrossing of the optical modes and of the dynamic optical spring effect, a position-squared vacuum coupling rate as large as g[over ˜]^{′}/2π=245  Hz is inferred between the optical Supermodes and the fundamental in-plane mechanical resonance of the structure at ω_{m}/2π=8.7  MHz, which in displacement units corresponds to a coupling coefficient of g^{′}/2π=1  THz/nm^{2}. For larger supermode splittings, selective excitation of the individual optical Supermodes is used to demonstrate optical trapping of the mechanical resonator with measured g[over ˜]^{′}/2π=46  Hz