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Electromagnetics and Photonics

Electro-Optics and Photonics Faculty Publications

2015

Articles 1 - 7 of 7

Full-Text Articles in Physics

Tungsten Disulphide Based All Fiber Q-Switching Cylindrical-Vector Beam Generation, J. Lin, K. Yan, Yong Zhou, L. X. Xu, C. Gu, Qiwen Zhan Nov 2015

Tungsten Disulphide Based All Fiber Q-Switching Cylindrical-Vector Beam Generation, J. Lin, K. Yan, Yong Zhou, L. X. Xu, C. Gu, Qiwen Zhan

Electro-Optics and Photonics Faculty Publications

We proposed and demonstrated an all fiber passively Q-switching laser to generate cylindrical-vectorbeam, a two dimensional material,tungsten disulphide (WS2), was adopted as a saturable absorber inside the laser cavity, while a few-mode fiber Bragg grating was used as a transverse mode-selective output coupler. The repetition rate of the Q-switching output pulses can be varied from 80 kHz to 120 kHz with a shortest duration of 958 ns. Attributed to the high damage threshold and polarization insensitivity of the WS2 based saturable absorber, the radially polarized beam and azimuthally polarized beam can be easily generated in the Q-switchingfiber laser.


Creation Of Identical Multiple Focal Spots With Prescribed Axial Distribution, Yanzhong Yu, Qiwen Zhan Oct 2015

Creation Of Identical Multiple Focal Spots With Prescribed Axial Distribution, Yanzhong Yu, Qiwen Zhan

Electro-Optics and Photonics Faculty Publications

We present a scheme for the construction of coaxially equidistant multiple focal spots with identical intensity profiles for each individual focus and a predetermined number and spacing. To achieve this, the radiation field from an antenna is reversed and then gathered by high numerical aperture objective lenses. Radiation patterns from three types of line sources, i.e., the electric current, magnetic current and electromagnetic current distributions, with cosine-squared taper are respectively employed to generate predominately longitudinally polarized bright spots, azimuthally polarized doughnuts, and focal spots with a perfect spherically symmetric intensity distribution. The required illuminations at the pupil plane of ...


Tailoring Optical Complex Field With Spiral Blade Plasmonic Vortex Lens, Guanghao Rui, Qiwen Zhan, Yiping Cui Sep 2015

Tailoring Optical Complex Field With Spiral Blade Plasmonic Vortex Lens, Guanghao Rui, Qiwen Zhan, Yiping Cui

Electro-Optics and Photonics Faculty Publications

Optical complex fields have attracted increasing interests because of the novel effects and phenomena arising from the spatially inhomogeneous state of polarizations and optical singularities of the light beam. In this work, we propose a spiral blade plasmonic vortex lens (SBPVL) that offers unique opportunities to manipulate these novel fields. The strong interaction between the SBPVL and the optical complex fields enable the synthesis of highly tunable plasmonic vortex. Through theoretical derivations and numerical simulations we demonstrated that the characteristics of the plasmonic vortex are determined by the angular momentum (AM) of the light, and the geometrical topological charge of ...


Tailoring Optical Complex Fields With Nano-Metallic Surfaces, Guanghao Rui, Qiwen Zhan Apr 2015

Tailoring Optical Complex Fields With Nano-Metallic Surfaces, Guanghao Rui, Qiwen Zhan

Electro-Optics and Photonics Faculty Publications

Recently there is an increasing interest in complex optical fields with spatially inhomogeneous state of polarizations and optical singularities. Novel effects and phenomena have been predicted and observed for light beams with these unconventional states. Nanostructured metallic thin film offers unique opportunities to generate, manipulate and detect these novel fields. Strong interactions between nano-metallic surfaces and complex optical fields enable the development of highly compact and versatile functional devices and systems. In this review, we first briefly summarize the recent developments in complex optical fields. Various nano-metallic surface designs that can produce and manipulate complex optical fields with tailored characteristics ...


Optimization-Free Optical Focal Field Engineering Through Reversing The Radiation Pattern From A Uniform Line Source, Yanzhong Yu, Qiwen Zhan Mar 2015

Optimization-Free Optical Focal Field Engineering Through Reversing The Radiation Pattern From A Uniform Line Source, Yanzhong Yu, Qiwen Zhan

Electro-Optics and Photonics Faculty Publications

A simple and flexible method is presented for the generation of optical focal field with prescribed characteristics. By reversing the field pattern radiated from a uniform line source, for which the electric current is constant along its extent, situated at the focus of a 4Pi focusing system formed by two confocal high-NA objective lenses, the required illumination distribution at the pupil plane for creating optical focal field with desired properties can be obtained. Numerical example shows that an arbitrary length optical needle with extremely high longitudinal polarization purity and consistent transverse size of ~0.36λ over the entire depth of ...


Tunable Narrow Band Difference Frequency Thz Wave Generation In Dast Via Dual Seed Ppln Opg, Brian Dolasinski, Peter E. Powers, Joseph W. Haus, Adam Cooney Feb 2015

Tunable Narrow Band Difference Frequency Thz Wave Generation In Dast Via Dual Seed Ppln Opg, Brian Dolasinski, Peter E. Powers, Joseph W. Haus, Adam Cooney

Electro-Optics and Photonics Faculty Publications

We report a widely tunable narrowband terahertz (THz) source via difference frequency generation (DFG). A narrowband THz source uses the output of dual seeded periodically poled lithium niobate (PPLN) optical parametric generators (OPG) combined in the nonlinear crystal 4-dimthylamino-N-methyl-4-stilbazolium-tosylate (DAST). We demonstrate a seamlessly tunable THZ output that tunes from 1.5 THz to 27 THz with a minimum bandwidth of 3.1 GHz. The effects of dispersive phase matching, two-photon absorption, and polarization were examined and compared to a power emission model that consisted of the current accepted parameters of DAST.


Role Of Antenna Modes And Field Enhancement In Second Harmonic Generation From Dipole Nanoantennas, Domenico De Ceglia, Maria Antonietta Vincenti, Costantino De Angelis, Andrea Locatelli, Joseph W. Haus, Michael Scalora Jan 2015

Role Of Antenna Modes And Field Enhancement In Second Harmonic Generation From Dipole Nanoantennas, Domenico De Ceglia, Maria Antonietta Vincenti, Costantino De Angelis, Andrea Locatelli, Joseph W. Haus, Michael Scalora

Electro-Optics and Photonics Faculty Publications

We study optical second harmonic generation from metallic dipole antennas with narrow gaps. Enhancement of the fundamental-frequency field in the gap region plays a marginal role on conversion efficiency. In the symmetric configuration, i.e., with the gap located at the center of the antenna axis, reducing gap size induces a significant red-shift of the maximum conversion efficiency peak. Either enhancement or inhibition of second-harmonic emission may be observed as gap size is decreased, depending on the antenna mode excited at the harmonic frequency. The second-harmonic signal is extremely sensitive to the asymmetry introduced by gap’s displacements with respect ...