12,921 research outputs found
Nanolithography using micro-scale mask enabled by hyperbolic metamaterial
No full textWe newly developed a nano-scale patterning method overcoming the diffraction limit of conventional photo-lithography technique by utilizing micro-scale aluminum mask-hyperbolic metamaterials hybrid structures, which is supported by our numerical simulation and experimental results
Efficient formulation of Raman amplifier propagation equations with average power analysis
No full textFor the first time, we derive efficient modeling equations for the average power analysis of Raman amplifiers (RAs) from the standard propagation equations. Applications of these equations to the numerical analysis of practical RA-based systems show a reduction in computation time of over two orders of magnitude compared with the direct integration approach based on ordinary coupled differential equations, while reproducing all the essential system performances precisely. In addition to enhanced computational efficiency, derived equations also give deeper insights into the detailed dynamics of RAs
Perturbative analytic theory of an ultrahigh-Q toroidal microcavity
Get PDFA perturbation theoretic approach is proposed as an efficient characterization tool for a tapered fiber coupled ultrahigh-quality factor (Q) toroidal microcavity with a small inverse aspect ratio. The Helmholtz equation with an assumption of quasi-TE/TM modes in local toroidal coordinates is solved via a power series expansion in terms of the inverse aspect ratio and the expanded eigenmode solutions are further manipulated iteratively to generate various characteristic metrics of the ultrahigh-Q toroidal microcavity coupled to a tapered fiber waveguide. Resonance wavelengths, free spectral ranges, cavity mode volumes, phase-matching conditions, and radiative Q factors are derived along with a mode characterization given by a characteristic equation. Calculated results are in excellent agreement with full vectorial finite-element simulations. The results are useful as a shortcut to avoid full numerical simulation, and also render intuitive insight into the modal properties of toroidal microcavities
Photoinduced Nonlinear Mixing of Terahertz Dipole Resonances in Graphene Metadevices
No full textWe demonstrate nonlinear mixing of terahertz dipole resonances in graphene metadevice. Ultrafast terahertz spectroscopy corroborates that the characteristic difference-frequency resonance indeed originates from the coupled interaction between graphene and meta-atoms
Terahertz second-order nonlinear optics in a graphene-metamaterial device: Difference-frequency generation
No full textWe show the first experimental demonstration of nonlinear second-order terahertz frequency generation in a graphene-metamaterial device. Characteristic ultrafast nature of graphene and strong metamaterials' nonlinear resonances enables to observe the nonlinear difference frequency generation
Photoinduced Nonlinear Mixing of Terahertz Dipole Resonances in Graphene Metadevices
No full textThe first experimental demonstration of nonlinear terahertz difference-frequency generation in a hybrid graphene meta-device is reported. Decades of research have revealed that terahertz-wave generation is impossible in single-layer graphene. This limitation is overcome and nonlinear terahertz generation by ultra-short optical pulse injection is demonstrated. This device is an essential step toward atomically thin, nonlinear terahertz optoelectronic components
Coupled structure for wide-band EDFA with gain and noise figure improvements from C to L-band ASE injection
No full textWe propose a novel structure for C plus L-band silica based wide-band erbium-doped fiber amplifiers (W-EDFA's), which use backward amplified spontaneous emission from the C-band EDFA as the pump-mediating injection source for the L-band amplifier unit. Experimental results show gain and noise figure improvements of over 2.6 dB and 0.6 dB, respectively, at -3.5 dBm of L-band input signal power, Spatially resolved numerical analysis confirms the pump-mediating effect of C-band backward ASE in the L-band EDFA for the gain and noise figure improvement, which also provides better understanding on the dynamics of C-band injection seed methods
Integration of single-crystal LiNbO3 thin film on silicon by laser irradiation and ion implantation-induced layer transfer
No full textintegration of high-quality ferroelectric thin films, e.g., LiNbO3, in planar device architectures on silicon substrates remains a technological challenge. The successful fabrication of a suspended micro-disk resonator structure (see figure) suggests that the method reported here -a combination of wafer bonding, ion implantation, and layer transfer induced by laser irradiation-may be useful in optoelectronic device applications
시공간적으로 유전율이 변조되는 광결정을 이용한 다기능 파라메트릭 소자
No full textA multifunctional parametric device using an optical material in which permittivity is spatiotemporally modulated according to the present invention may be used as a frequency converter and oscillator according to a design characteristic. Since a converted and oscillated frequency is determined according to a modulation frequency of a thin slab of which permittivity is spatiotemporally modulated, a user is capable of actively determining a frequency modulation and oscillation characteristic using the parametric device
- …
