Browsing by Author "Tung, J. C."

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Analytical representation for structured light generated by astigmatic transformation of Hermite-Gaussian beams
(2018-01-01)
Hsieh, Y. H.
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Tuan, P. H.
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Tung, J. C.
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Liang, H. C.
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Su, K. W.
Theoretical wave functions are analytically derived to formulate the propagation evolution of the Hermite-Gaussian (HG) beams transformed by single lens astigmatic mode converter with arbitrary angle. The derived wave functions are associated with the combination of the rotation transform and the antisymmetric fractional Fourier transform. The derived formula are validated by the mode conversions of high-order HG beams generated by an off-axis diode-pumped solid-state laser. In addition to validation, the creation and evolution of vortex structures in the transformed HG beams are numerically manifested. The present theoretical model can be applied not only to characterize the evolution of the transformed beams but to design the optical vortex beams with various forms.
Astigmatism inducing the degenerate effect in nearly hemispherical cavities: Generation of three-dimensional structured light
(2017-01-01)
Tung, J. C.
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Hsieh, Y. H.
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Liang, H. C.
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Su, K. W.
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Huang, K. F.
We originally perform an analytical form to explore the influence of the astigmatism on the degenerate effect in nearly hemispherical cavities. The frequency spectrum near hemispherical cavities clearly reveals that not only the difference of cavity lengths between each degeneracies but also frequency gaps have significant difference from non-hemispherical cavities. We further thoroughly demonstrate the laser experiment under the condition of nearly hemispherical cavities to confirm the theoretical exploration that the transverse topology of three-dimensional (3D) structured light in the degenerate cavities is well localized on the Lissajous curves.
Bottle beam generation from a frequency-doubled Nd:YVO4 laser
(2018-11-08)
Tung, J. C.
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Ma, Y. Y.
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Miyamoto, K.
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Chen, Y. F.
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Omatsu, T.
We demonstrate, for the first time, the direct generation of a bottle beam with a well-isolated threedimensional zero-intensity dark core (high potential barrier) from a compact intracavity frequency-doubled Nd:YVO4 laser with a nearly hemispherical cavity. We also numerically calculate the physical properties of the generated bottle beam using a coherent superposition of a series of frequency-locked Laguerre-Gaussian modes.
Bottle beam generation from a frequency-doubled Nd:YVO4 laser with a tightly end-pumping geometry
(2018-01-01)
Tung, J. C.
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Ma, Y. Y.
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Chen, Y. F.
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Miyamoto, K.
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Omatsu, T.
We first demonstrated the generation of an optical bottle beam with a zero-intensity region surrounded by three-dimensional bright regions from an intra-cavity frequency-doubled Nd:YVO4 laser with a nearly hemispherical cavity configuration. We also numerically analyzed the components of the generated bottle beam which consists of a series of Laguerre-Gaussian modes. The experimental results can be excellently reconstructed with the theoretical model.
Characterizing classical periodic orbits from quantum Green's functions in two-dimensional integrable systems: Harmonic oscillators and quantum billiards
(2017-01-30)
Chen, Y. F.
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Tung, J. C.
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Tuan, P. H.
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Yu, Y. T.
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Liang, H. C.
A general method is developed to characterize the family of classical periodic orbits from the quantum Green's function for the two-dimensional (2D) integrable systems. A decomposing formula related to the beta function is derived to link the quantum Green's function with the individual classical periodic orbits. The practicality of the developed formula is demonstrated by numerically analyzing the 2D commensurate harmonic oscillators and integrable quantum billiards. Numerical analyses reveal that the emergence of the classical features in quantum Green's functions principally comes from the superposition of the degenerate states for 2D harmonic oscillators. On the other hand, the damping factor in quantum Green's functions plays a critical role to display the classical features in mesoscopic regime for integrable quantum billiards, where the physical function of the damping factor is to lead to the coherent superposition of the nearly degenerate eigenstates.
Characterizing the propagation evolution of wave patterns and vortex structures in astigmatic transformations of Hermite-Gaussian beams
(2018-01-01)
Chen, Y. F.
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Chang, C. C.
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Lee, C. Y.
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Tung, J. C.
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Liang, H. C.
Theoretical wave functions are analytically derived to characterize the propagation evolution of the Hermite-Gaussian (HG) beams transformed by a single-lens astigmatic mode converter with arbitrary angle. The derived wave functions are related to the combination of the rotation transform and the antisymmetric fractional Fourier transform. The derived formula is systematically validated by using an off-axis diode-pumped solid-state laser to generate various high-order HG beams for mode conversions. In addition to validation, the creation and evolution of vortex structures in the transformed HG beams are numerically manifested. The present theoretical analyses can be used not only to characterize the evolution of the transformed beams but to design the optical vortex beams with various forms.
Direct generation of a 'bottle beam' from an end-pumped Nd:YVO4 laser with second-harmonic generation
(2018-01-01)
Tung, J. C.
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Ma, Y. Y.
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Chen, Y. F.
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Huang, K. F.
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Omatsu, T.
We have demonstrated, for the first time, the generation of an optical 'bottle beam' with a 'zero-intensity' region surrounded by three-dimensional bright regions from an intra-cavity frequency-doubled Nd:YVO4 laser with a nearly hemispherical cavity configuration.
Exploring optical properties of Nd-doped vanadates with intracavity self-mode locking
(2013)
Liang, H. C.
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Tung, J. C.
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Tsou, C. H.
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Su, K. W.
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Chen, Y. F.
We employ an intracavity self-mode-locked laser to systematically measure the group refractive indices and the thermo-optic coefficients for Nd:GdVO4, Nd:YVO4 and Nd:LuVO4 crystals at 1064 nm. We further make a detailed comparison between the present results and those currently reported in the literature. All the experimental results can be found to be fairly consistent with the recent reported data
Exploring spatio-temporal dynamics of an optically pumped semiconductor laser with intracavity second harmonic generation
(2013)
Lee, Y. C.
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Liang, H. C.
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Tung, J. C.
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Su, K. W.
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Chen, Y. F.
We experimentally observe an intriguing phenomenon of complex spatio-temporal dynamics in a commercial optically pumped semiconductor laser with intracavity second harmonic generation. We numerically verify that the experimental results come from the total mode locking of TEM00 and higher-order modes with significant astigmatism. The scenarios of the spatio-temporal dynamics are quite similar to the phenomena in soft-aperture Kerr-lens mode locked Ti:sapphire lasers.
Exploring the effect of fractional degeneracy and the emergence of ray-wave duality in solid-state lasers with off-axis pumping
(2013-07-18)
Chen, Y. F.
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Tung, J. C.
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Chiang, P. Y.
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Liang, H. C.
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Huang, K. F.
We employ the inhomogeneous Helmholtz equation to explore the influence of the fractional degeneracy and the pump distribution on the resonant lasing mode. Theoretical analyses clearly reveal the relationship between the fractional degeneracy and the emergence of the ray-wave duality. Furthermore, we perform thorough laser experiments to confirm the theoretical exploration that the resonant modes near the degenerate cavities are well localized on the ray trajectories under the condition of the off-axis pumping. We also exploit the derived wave functions to calculate the resonant strengths that can noticeably manifest the enhancements of the output powers in the degenerate cavities.
Exploring the self-mode locking and vortex structures of nonplanar elliptical modes in selectively end-pumped Nd: YVO4 lasers: manifestation of large fractional orbital angular momentum
(2017-09-18)
Tung, J. C.
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Omatsu, T.
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Liang, H. C.
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Huang, K. F.
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Chen, Y. F.
An end-pumped Nd: YVO4 laser under selective pumping is used to excite lasing modes with transverse patterns performed to exhibit the characteristics of multiple spots arranged on elliptical features near degenerate cavities. The spatial distribution of elliptical lasing modes is clearly revealed to be localized on the nonplanar ray orbits, so-called nonplanar elliptical modes, which possess large fractional orbital angular momentum. Moreover, temporal dynamics for the output emission of nonplanar elliptical modes are verified to obtain self-mode-locked operation. We further numerically manifest not only the influence of radial-asymmetry distributions on the vortex structures of nonplanar elliptical modes, but also the vector field of transverse lasing modes altered with twisting phase structures in the propagation direction. (C) 2017 Optical Society of America
Exploring vortex structures in orbital-angular-momentum beams generated from planar geometric modes with a mode converter
(2016-10-03)
Tung, J. C.
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Liang, H. C.
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Lu, T. H.
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Huang, K. F.
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Chen, Y. F.
It is theoretically demonstrated that the planar geometric mode with a pi/2 mode converter, so called the circularly geometric mode, can be solved from the inhomogeneous Helmholtz equation by considering the pump distribution on the lasing mode. Theoretical analysis clearly reveal that the vortex structures of circularly geometric modes are determined by the minimum order of transverse lasing modes, the total number of transverse lasing modes and the degenerate condition in the cavity. Moreover, we experimentally manifest that the circularly geometric mode can be generated from the selective pumped solid-state laser with an external pi/2 mode converter. To explore the vortex structures of the generated geometric modes, the interference patterns are performed by an experimental apparatus consisting of a Mach-Zehnder interferometer. The good agreement between experimental observations and numerical calculations confirms the analysis of vortex structures is reliable. (C) 2016 Optical Society of America
Extracting trajectory equations of classical periodic orbits from the quantum eigenmodes in two-dimensional integrable billiards
(2017-02-21)
Hsieh, Y. H.
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Yu, Y. T.
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Tuan, P. H.
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Tung, J. C.
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Huang, K. F.
The trajectory equations for classical periodic orbits in the equilateral-triangular and circular billiards are systematically extracted from quantum stationary coherent states. The relationship between the phase factors of quantum stationary coherent states and the initial positions of classical periodic orbits is analytically derived. In addition, the stationary coherent states with noncoprime parametric numbers are shown to correspond to the multiple periodic orbits, which cannot be explicable in the one-particle picture. The stationary coherent states are further verified to be linked to the resonant modes that are generally observed in the experimental wave system excited by a localized and unidirectional source. The excellent agreement between the resonant modes and the stationary coherent states not only manifests the importance of classical features in experimental systems but also paves the way to manipulate the mesoscopic wave functions localized on the periodic orbits for applications.
Flexible generation of optical beams with quasicrystalline structures via astigmatism induced by a tilted lens
(2012-12-01)
Tung, J. C.
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Liang, H. C.
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Tsou, C. H.
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Su, K. W.
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Chen, Y. F.
We theoretically show that a family of optical beams with vortex-lattice structures can be reliably generated by tilting the focal lens to introduce the relative phases between the interfering beams. We also experimentally generate the quasicrystal beams to confirm the theoretical analysis. With the analytical wave functions and experimental patterns, a variety of vortex-lattice structures are manifested.
Formation and recurrence of quasicrystalline patterns from quantum dynamics of suddenly released matter waves: Analogous manifestation of optical waves
(2012-07-01)
Liang, H. C.
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Tung, J. C.
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Wu, T. W.
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Tsou, C. H.
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Lin, Y. C.
We analytically and numerically verify that two-dimensional (2D) quasicrystalline matter waves can be formed from the free-time evolution of multiple Gaussian waves regularly distributed on a circular ring. We also demonstrate that an interesting recurrence phenomenon can be manifested by adding an extra Gaussian wave on the center of multiple Gaussian waves uniformly distributed on a ring. We finally employ an optical experiment for the coherent light passing through the mask to analogously illustrate the formation of 2D quasicrystalline patterns and the associated recurrence. Copyright (C) EPLA, 2012
Fractal frequency spectrum in laser resonators and three-dimensional geometric topology of optical coherent waves
(2016-08-03)
Tung, J. C.
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Tuan, P. H.
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Liang, H. C.
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Huang, K. F.
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Chen, Y. F.
We theoretically verify that the symmetry breaking in spherical resonators can result in a fractal frequency spectrum that is full of numerous newaccidental degeneracies to cluster around the unperturbed degenerate cavity. We further experimentally discover that the fractal frequency spectrum excellently reflects the intimate connection between the emission power and the degenerate mode numbers. It is observed that the wave distributions of lasing modes at the accidental degeneracies are strongly concentrated on three-dimensional (3D) geometric topology. Considering the overlapping effect, the wave representation of the coherent states is analytically derived to manifest the observed 3D geometric surfaces.
Generalized wave-packet formulation with ray-wave connections for geometric modes in degenerate astigmatic laser resonators
(2019-11-01)
Chen, Y. F.
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Tung, J. C.
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Hsieh, M. X.
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Hsieh, Y. H.
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Liang, H. C.
The parametric equations for periodic rays in degenerate astigmatic laser resonators are derived in a generalized way. The derived parametric equations clearly reveal the formation of Lissajous geometric modes with phase variation along the propagation. Using the representation of a quantum coherent state, a generalized wave-packet formula is derived to connect with the periodic rays of geometric modes. The derived wave-packet formula is not only validated through comparing with various experimental patterns, but also is directly exploited to manifest the spatial asymmetries of Lissajous lasing modes due to a highly transmissive output coupler. (C) 2019 Optical Society of America
Generating high-peak-power structured lights in selectively pumped passively Q-switched lasers with astigmatic mode transformations
(2017-12-01)
Chang, C. C.
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Hsieh, Y. H.
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Lee, C. Y.
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Sung, C. L.
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Tuan, P. H.
Various high-order Hermite-Gaussian (HG) modes with high repetition rates and high peak powers are systematically generated by designing the cavity configuration to satisfy the criterion of the passive Q-switching. For the HG(m,0) modes with the order m = 1-9, the pulse repetition rate can exceed 100 kHz with peak power higher than 0.3 kW. For the HG(m,m) modes with the order m = 1-10, the pulse repetition rate can be up to 37 kHz with peak power higher than 0.35 kW. Furthermore, the high-order HG beams is transformed by using an astigmatic mode converter to generate various structured lights with optical vortices. Experimental patterns of the transformed high-order HG beams in the propagation are theoretically analyzed and the phase structures are numerically manifested.
Generating laser transverse modes analogous to quantum Green's functions of two-dimensional harmonic oscillators
(2017-12-01)
Tung, J. C.
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Hsieh, Y. H.
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Omatsu, T.
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Huang, K. F.
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Chen, Y. F.
We theoretically analyzed the relationship between quantum Green's functions of two-dimensional harmonic oscillators and radial-order Laguerre - Gaussian laser modes of spherical resonators. By using a nearly hemispherical resonator and a tight focusing in the end-pumped solid-state laser, we successfully generated various laser transverse modes analogous to quantum Green's functions. We further experimentally and numerically verified that the transverse order associated with quantum Green's functions is noticeably raised with increasing the pump power induced by the thermal effect. More importantly, the high lasing efficiency and the salient structure enable the present laser source to be used in exploring the light -matter interaction. (C) 2017 Chinese Laser Press
Generation of pseudonondiffracting optical beams with superlattice structures
(2013-10-07)
Tsou, C. H.
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Wu, T. W.
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Tung, J. C.
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Liang, H. C.
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Tuan, P. H.
We demonstrate an approach to generate a class of pseudonondiffracting optical beams with the transverse shapes related to the superlattice structures. For constructing the superlattice waves, we consider a coherent superposition of two identical lattice waves with a specific relative angle in the azimuthal direction. We theoretically derive the general conditions of the relative angles for superlattice waves. In the experiment, a mask with multiple apertures which fulfill the conditions for superlattice structures is utilized to generate the pseudonondiffracting superlattice beams. With the analytical wave functions and experimental patterns, the pseudonondiffracting optical beams with a variety of structures can be generated systematically. (C) 2013 Optical Society of America