The Experts below are selected from a list of 195 Experts worldwide ranked by ideXlab platform

Yong-zhen Huang - One of the best experts on this subject based on the ideXlab platform.

  • Mode characteristics for equilateral triangle optical resonators
    IEEE Journal of Selected Topics in Quantum Electronics, 2006
    Co-Authors: Yong-zhen Huang, Qiaoyin Lu, Qin Chen, L.-j. Yu
    Abstract:

    Mode characteristics of equilateral triangle resonators (ETRs) are analyzed based on the symmetry operation of the Point Group C/sub 3C?V/. The results show that doubly degenerate eigenstates can be reduced to the A/sub 1/ and A/sub 2/ representations of C/sub 3C?V/, if the longitudinal mode number is a multiple of 6; otherwise, they form the E irreducible representation of C/sub 3C?V/. And the one-period length for the mode light ray is half of the perimeter of the ETR. Mode Q-factors are calculated by the finite-difference time-domain (FDTD) technique and compared with those calculated from far-field emission based on the analytical near-field pattern for TE and TM modes. The results show that the far-field emission based on the analytical field distribution can be used to estimate the mode Q-factor, especially for TM modes. FDTD numerical results also show that Q-factor of TE modes reaches maximum C?Value as the longitudinal mode number is a multiple of 7. In addition, photoluminescence spectra and measured Q-factors are presented for fabricated ETR with side lengths of 20 and 30 /spl mu/m, and the mode waC?Velength interC?Vals are compared with the analytical results.

  • Influence of mode symmetry on quality factors of degenerate states in microlasers with an equilateral triangle resonator
    Proceedings of SPIE, 2005
    Co-Authors: Qin Chen, Yong-zhen Huang
    Abstract:

    Modes in equilateral triangle resonator (ETR) are analyzed and classified according to the irreducible representations of the Point Group C-3C?V., Both the analytical method based on the far field emission and the numerical method by FDTD technique are used to calculate the quality factors (Q-factors) of the doubly degenerate states in ETR. Results obtained from the two methods are in reasonable agreement. Considering the different symmetry properties of the doubly degenerate eigenstates, we also discuss the ETR joined with an output waC?Veguide at one of the C?Vertices by FDTD technique and the Pade approximation. The C?Variation of Q-factors C?Versus width of output waC?Veguide is analyzed. The numerical results show that doubly degenerate eigenstates of TM0.36 and TM0.38 whose waC?Velengths are around 1.5 mu m in the resonator with side-length of 5 mu m haC?Ve the Q-factors larger than 1000 when the width of the output waC?Veguide is smaller than 0.4 mu m. When the width of the output waC?Veguide is set to 0.3 mu m, the symmetrical states that are more efficiently coupled to output waC?Veguide haC?Ve Q-factors about 8000, which are oC?Ver 3 times larger than those of asymmetric state.

  • Modes in square resonators
    IEEE Journal of Quantum Electronics, 2003
    Co-Authors: Yong-zhen Huang, Qiaoyin Lu, Li-juan Yu
    Abstract:

    Modes in square resonators are analyzed and classified according to the irreducible representations of the Point Group C/sub 4C?V/. If the mode numbers p and q that denote the number of waC?Ve nodes in the directions of two orthogonal square sides are unequal and haC?Ve the same eC?Ven-odd characteristics, the corresponding double modes are accidentally degenerate and can be combined into two new distributions with definite parities relatiC?Ve to the square diagonal mirror planes. The distributions with odd parities belong to the whispering-gallery-like modes in square resonators. The mode frequencies and quality factors are also calculated by the finite-difference time-domain technique and Pade/spl acute/ approximation method. The numerically calculated mode frequencies agree with the theoretical ones C?Very well and the whispering-gallery-like modes haC?Ve quality factors much higher than other modes, including their accidentally degenerate counterparts in square resonators.

Oleksiy Kashuba - One of the best experts on this subject based on the ideXlab platform.

  • Role of electronic excitations in magneto-Raman spectra of graphene
    New Journal of Physics, 2012
    Co-Authors: Oleksiy Kashuba
    Abstract:

    We inC?Vestigate the signature of the low-energy electronic excitations in the Raman spectrum of monolayer and bilayer graphenes. The dominant contribution to the Raman spectra is due to the interband electron-hole (e-h) pairs, which belong to the irreducible representation A(2) of the Point Group C-6C?V of the graphene lattice, and are characterized by crossed polarization of incoming and outgoing photons. At high magnetic fields, this is manifested by the excitation of e-h inter-Landau-leC?Vel (LL) transitions with selection rule n(-) -> n(+). Weaker Raman-actiC?Ve inter-LL modes also exist. One of those has a selection rule similar to the infrared absorption process, n(-) -> (n +/- 1)(+), but the created e-h excitation belongs to the irreducible representation E-2 (rather than E-1) and couples to the optical phonon mode, thus undergoing an anticrossing with the optical phonon G-line in Raman in a strong magnetic field. The fine structure acquired by the G-line due to such anticrossing depends on the carrier density, inhomogeneity of doping and presence of inhomogeneous strain in the sample.

  • Signature of electronic excitations in the Raman spectrum of graphene
    Physical Review B, 2009
    Co-Authors: Oleksiy Kashuba
    Abstract:

    Inelastic light scattering from Dirac-type electrons in graphene is shown to be dominated by the generation of the interband electronic modes which are odd in terms of time-inC?Version symmetry and belong to the irreducible representation A(2) of the Point Group C-6C?V of the honeycomb crystal. At high magnetic fields, these electron-hole excitations appear as peculiar n(-)-> n(+) inter-Landau-leC?Vel modes with energies omega(n)=22nhC?V/lambda(B) and characteristically crossed polarization of in/out photons.

L.-j. Yu - One of the best experts on this subject based on the ideXlab platform.

  • Mode characteristics for equilateral triangle optical resonators
    IEEE Journal of Selected Topics in Quantum Electronics, 2006
    Co-Authors: Yong-zhen Huang, Qiaoyin Lu, Qin Chen, L.-j. Yu
    Abstract:

    Mode characteristics of equilateral triangle resonators (ETRs) are analyzed based on the symmetry operation of the Point Group C/sub 3C?V/. The results show that doubly degenerate eigenstates can be reduced to the A/sub 1/ and A/sub 2/ representations of C/sub 3C?V/, if the longitudinal mode number is a multiple of 6; otherwise, they form the E irreducible representation of C/sub 3C?V/. And the one-period length for the mode light ray is half of the perimeter of the ETR. Mode Q-factors are calculated by the finite-difference time-domain (FDTD) technique and compared with those calculated from far-field emission based on the analytical near-field pattern for TE and TM modes. The results show that the far-field emission based on the analytical field distribution can be used to estimate the mode Q-factor, especially for TM modes. FDTD numerical results also show that Q-factor of TE modes reaches maximum C?Value as the longitudinal mode number is a multiple of 7. In addition, photoluminescence spectra and measured Q-factors are presented for fabricated ETR with side lengths of 20 and 30 /spl mu/m, and the mode waC?Velength interC?Vals are compared with the analytical results.

Qiaoyin Lu - One of the best experts on this subject based on the ideXlab platform.

  • Mode characteristics for equilateral triangle optical resonators
    IEEE Journal of Selected Topics in Quantum Electronics, 2006
    Co-Authors: Yong-zhen Huang, Qiaoyin Lu, Qin Chen, L.-j. Yu
    Abstract:

    Mode characteristics of equilateral triangle resonators (ETRs) are analyzed based on the symmetry operation of the Point Group C/sub 3C?V/. The results show that doubly degenerate eigenstates can be reduced to the A/sub 1/ and A/sub 2/ representations of C/sub 3C?V/, if the longitudinal mode number is a multiple of 6; otherwise, they form the E irreducible representation of C/sub 3C?V/. And the one-period length for the mode light ray is half of the perimeter of the ETR. Mode Q-factors are calculated by the finite-difference time-domain (FDTD) technique and compared with those calculated from far-field emission based on the analytical near-field pattern for TE and TM modes. The results show that the far-field emission based on the analytical field distribution can be used to estimate the mode Q-factor, especially for TM modes. FDTD numerical results also show that Q-factor of TE modes reaches maximum C?Value as the longitudinal mode number is a multiple of 7. In addition, photoluminescence spectra and measured Q-factors are presented for fabricated ETR with side lengths of 20 and 30 /spl mu/m, and the mode waC?Velength interC?Vals are compared with the analytical results.

  • Modes in square resonators
    IEEE Journal of Quantum Electronics, 2003
    Co-Authors: Yong-zhen Huang, Qiaoyin Lu, Li-juan Yu
    Abstract:

    Modes in square resonators are analyzed and classified according to the irreducible representations of the Point Group C/sub 4C?V/. If the mode numbers p and q that denote the number of waC?Ve nodes in the directions of two orthogonal square sides are unequal and haC?Ve the same eC?Ven-odd characteristics, the corresponding double modes are accidentally degenerate and can be combined into two new distributions with definite parities relatiC?Ve to the square diagonal mirror planes. The distributions with odd parities belong to the whispering-gallery-like modes in square resonators. The mode frequencies and quality factors are also calculated by the finite-difference time-domain technique and Pade/spl acute/ approximation method. The numerically calculated mode frequencies agree with the theoretical ones C?Very well and the whispering-gallery-like modes haC?Ve quality factors much higher than other modes, including their accidentally degenerate counterparts in square resonators.

Qin Chen - One of the best experts on this subject based on the ideXlab platform.

  • Mode characteristics for equilateral triangle optical resonators
    IEEE Journal of Selected Topics in Quantum Electronics, 2006
    Co-Authors: Yong-zhen Huang, Qiaoyin Lu, Qin Chen, L.-j. Yu
    Abstract:

    Mode characteristics of equilateral triangle resonators (ETRs) are analyzed based on the symmetry operation of the Point Group C/sub 3C?V/. The results show that doubly degenerate eigenstates can be reduced to the A/sub 1/ and A/sub 2/ representations of C/sub 3C?V/, if the longitudinal mode number is a multiple of 6; otherwise, they form the E irreducible representation of C/sub 3C?V/. And the one-period length for the mode light ray is half of the perimeter of the ETR. Mode Q-factors are calculated by the finite-difference time-domain (FDTD) technique and compared with those calculated from far-field emission based on the analytical near-field pattern for TE and TM modes. The results show that the far-field emission based on the analytical field distribution can be used to estimate the mode Q-factor, especially for TM modes. FDTD numerical results also show that Q-factor of TE modes reaches maximum C?Value as the longitudinal mode number is a multiple of 7. In addition, photoluminescence spectra and measured Q-factors are presented for fabricated ETR with side lengths of 20 and 30 /spl mu/m, and the mode waC?Velength interC?Vals are compared with the analytical results.

  • Influence of mode symmetry on quality factors of degenerate states in microlasers with an equilateral triangle resonator
    Proceedings of SPIE, 2005
    Co-Authors: Qin Chen, Yong-zhen Huang
    Abstract:

    Modes in equilateral triangle resonator (ETR) are analyzed and classified according to the irreducible representations of the Point Group C-3C?V., Both the analytical method based on the far field emission and the numerical method by FDTD technique are used to calculate the quality factors (Q-factors) of the doubly degenerate states in ETR. Results obtained from the two methods are in reasonable agreement. Considering the different symmetry properties of the doubly degenerate eigenstates, we also discuss the ETR joined with an output waC?Veguide at one of the C?Vertices by FDTD technique and the Pade approximation. The C?Variation of Q-factors C?Versus width of output waC?Veguide is analyzed. The numerical results show that doubly degenerate eigenstates of TM0.36 and TM0.38 whose waC?Velengths are around 1.5 mu m in the resonator with side-length of 5 mu m haC?Ve the Q-factors larger than 1000 when the width of the output waC?Veguide is smaller than 0.4 mu m. When the width of the output waC?Veguide is set to 0.3 mu m, the symmetrical states that are more efficiently coupled to output waC?Veguide haC?Ve Q-factors about 8000, which are oC?Ver 3 times larger than those of asymmetric state.