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Geng W, Fang Y, Bao C, Pan Z, Yue Y. Emission of five OAM dispersive waves in dispersion-engineered double-ring core fiber. Sci Rep 2024; 14:8474. [PMID: 38605163 PMCID: PMC11009397 DOI: 10.1038/s41598-024-57587-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 03/19/2024] [Indexed: 04/13/2024] Open
Abstract
Beams carrying orbital angular momentum (OAM) have exhibited significant potential across various fields, such as metrology, image coding, and optical communications. High-performance broadband coherent OAM sources are critical to the operation of optical systems. The emission of dispersive waves facilitates the efficient transfer of energy to distant spectral domains while preserving the coherence among the generated frequency components. Light sources that maintain consistency over a wide range can increase the efficiency of optical communication systems and improve the measurement accuracy in imaging and metrology. In this work, we propose a germanium-doped double ring-core fiber for five OAM dispersive waves (DWs) generation. The OAM1,1 mode supported in the fiber exhibits three zero-dispersion wavelengths (ZDWs) located at 1275, 1720 and 2325 nm. When pumped under normal dispersion, the output spectrum undergoes broadening and exhibits five DWs, situated around 955, 1120, 1450, 2795 and 2965 nm, respectively. Concomitant with blue-shifted and red-shifted dispersive waves, the spectrum spans from 895 to 3050 nm with high coherence. The effect of the fiber and input pulse parameters on DWs generation, as well as the underlying dynamics of the dispersive wave generation process, are discussed. As expected, the number and location of DWs generated in the output spectrum have agreement with the prediction of the phase-matching condition. Overall, this multiple DWs generation method in the proposed fiber paves the way for developing efficient and coherent OAM light sources in fiber-based optical systems.
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Affiliation(s)
- Wenpu Geng
- Institute of Modern Optics, Nankai University, Tianjin, 300350, China
| | - Yuxi Fang
- Institute of Modern Optics, Nankai University, Tianjin, 300350, China
| | - Changjing Bao
- Department of Electrical Engineering, University of Southern California, Los Angeles, CA, 90089, USA
| | - Zhongqi Pan
- Department of Electrical & Computer Engineering, University of Louisiana at Lafayette, Lafayette, LA, 70504, USA
| | - Yang Yue
- School of Information and Communications Engineering, Xi'an Jiaotong University, Xi'an, 710049, China.
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2
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Napiorkowski M, Urbanczyk W. Effect of core ellipticity and core-induced thermal stress on the conversion of LP 11 modes to vector vortex modes in gradually twisted highly birefringent fibers. OPTICS EXPRESS 2023; 31:9631-9656. [PMID: 37157529 DOI: 10.1364/oe.479219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We study the effect of the core ellipticity and core-induced thermal stress on the conversion of LP11 modes to vortex modes in gradually twisted highly birefringent PANDA fibers using an improved perturbation-based modeling method. We show that these two technologically unavoidable factors have a significant impact on the conversion process, which manifests itself in shortening the conversion length, altering the assignment between the input LP11 modes and output vortex modes, and modifying the vortex mode structure. In particular, we demonstrate that for certain fiber geometries, it is possible to obtain output vortex modes with parallel and antiparallel spins and orbital angular momenta. The simulation results obtained using the modified method are in good agreement with recently published experimental data. Furthermore, the proposed method provides reliable guidelines for choosing fiber parameters that ensure a short conversion length and the desired polarization structure of the output vortex modes.
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Baca-Montero ER, Andrade-Ambriz YA, Shulika OV. How to compress ultrashort vortex pulses. APPLIED OPTICS 2023; 62:B170-B177. [PMID: 37132903 DOI: 10.1364/ao.477249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Potential applications of ultrashort vortex pulses (ultrashort pulses with helical wavefronts) require compact tools to compensate for dispersion during their generation and propagation. In this work, a global simulated-annealing optimization algorithm, based on analysis of the temporal properties and waveforms of femtosecond vortex pulses, is used to design and optimize chirped mirrors. Performances of the algorithm through different optimization approaches and chirped mirror designs are presented.
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Yang J, Wang Y, Fang Y, Geng W, Zhao W, Bao C, Ren Y, Wang Z, Liu Y, Pan Z, Yue Y. Over-Two-Octave Supercontinuum Generation of Light-Carrying Orbital Angular Momentum in Germania-Doped Ring-Core Fiber. SENSORS (BASEL, SWITZERLAND) 2022; 22:6699. [PMID: 36081158 PMCID: PMC9459936 DOI: 10.3390/s22176699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/04/2022] [Accepted: 07/08/2022] [Indexed: 06/15/2023]
Abstract
In this paper, we design a silica-cladded Germania-doped ring-core fiber (RCF) that supports orbital angular momentum (OAM) modes. By optimizing the fiber structure parameters, the RCF possesses a near-zero flat dispersion with a total variation of <±30 ps/nm/km over 1770 nm bandwidth from 1040 to 2810 nm for the OAM1,1 mode. A beyond-two-octave supercontinuum spectrum of the OAM1,1 mode is generated numerically by launching a 40 fs 120 kW pulse train centered at 1400 nm into a 12 cm long designed 50 mol% Ge-doped fiber, which covers 2130 nm bandwidth from 630 nm to 2760 nm at −40 dB of power level. This design can serve as an efficient way to extend the spectral coverage of beams carrying OAM modes for various applications.
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Affiliation(s)
- Jian Yang
- Institute of Modern Optics, Nankai University, Tianjin 300350, China
| | - Yingning Wang
- Institute of Modern Optics, Nankai University, Tianjin 300350, China
| | - Yuxi Fang
- Institute of Modern Optics, Nankai University, Tianjin 300350, China
| | - Wenpu Geng
- Institute of Modern Optics, Nankai University, Tianjin 300350, China
| | - Wenqian Zhao
- Institute of Modern Optics, Nankai University, Tianjin 300350, China
| | - Changjing Bao
- Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Yongxiong Ren
- Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Zhi Wang
- Institute of Modern Optics, Nankai University, Tianjin 300350, China
| | - Yange Liu
- Institute of Modern Optics, Nankai University, Tianjin 300350, China
| | - Zhongqi Pan
- Department of Electrical & Computer Engineering, University of Louisiana at Lafayette, Lafayette, LA 70504, USA
| | - Yang Yue
- School of Information and Communications Engineering, Xi’an Jiaotong University, Xi’an 710049, China
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Bernas M, Napiorkowski M, Zolnacz K, Statkiewicz-Barabach G, Kiczor A, Mergo P, Urbanczyk W. Fiber-based vortex beam source operating in a broadband or tunable mode. OPTICS EXPRESS 2022; 30:27715-27729. [PMID: 36236937 DOI: 10.1364/oe.463828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 06/13/2022] [Indexed: 06/16/2023]
Abstract
We demonstrate a fiber-based optical vortex beam source operating in broadband or tunable mode in the spectral range of 1100-1400 nm. The vector vortices of the total angular momenta equal to +2, 0, and -2 are obtained by converting the respective linearly polarized (LP11) modes of the two-mode birefringent PANDA fiber with stress-applying elements by gradually twisting its output section. At the input end, the PANDA fiber is powered by broadband supercontinuum or tunable Raman solitons generated in the LP11 polarization modes of a birefringent microstructured fiber with a specially designed dispersion profile and coupled to the respective LP11 modes of the PANDA fiber. Two pulse lasers operating in different regimes (1 ns/1064 nm and 190 fs/1037 nm) were used as the pump to generate supercontinuum or tunable solitons directly in the LP11 modes of the microstructured fiber purely excited with a special Wollaston prism-based method. The high modal and polarization purities of the beams after successive transformations were experimentally confirmed. We also proved the vortex nature of the output beams using shearing interferometry.
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Dacha SK, Zhu W, Agrawal A, Ritter KJ, Murphy TE. Nonlinear rotation of spin-orbit coupled states in hollow ring-core fibers. OPTICS EXPRESS 2022; 30:18481-18495. [PMID: 36221648 DOI: 10.1364/oe.453944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 04/23/2022] [Indexed: 06/16/2023]
Abstract
We experimentally demonstrate that when two spin-orbit coupled orbital angular momentum (OAM) modes of opposite topological charge co-propagate in the Kerr nonlinear regime in a hollow ring-core optical fiber, the vectorial mode superposition exhibits a unique power-dependent rotation effect. This effect is analogous to nonlinear polarization rotation in single-mode fibers, however, the added spatial dimension produces a visually observable rotation of the spatial pattern emerging from the fiber when imaged through a linear polarizer. A dielectric metasurface q-plate was designed and fabricated to excite the desired mode combination in a hollow ring-core fiber that supports stable propagation of OAM modes. The observed spatial patterns show strong agreement with numerical simulations of the vector coupled nonlinear Schrödinger equations. These results constitute the first measurements of what can be described as the spin-orbit coupled generalization of the nonlinear polarization rotation effect.
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Li D, Chang J, Li D, Ji L, Liang W, Xu L, Zhang L, Xi T, Hao Z. Intense vector supercontinuum radiation from femtosecond filamentation. OPTICS EXPRESS 2022; 30:17567-17576. [PMID: 36221576 DOI: 10.1364/oe.457333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 04/28/2022] [Indexed: 06/16/2023]
Abstract
Intense vector supercontinuum (SC) radiation with spatial polarization is obtained by using 800nm femtosecond vector laser beams in the air. The SC generated by azimuthally, radially, cylindrically polarized beams, and higher-order vector beams are investigated, respectively. The results show that the SC generated by vector beams is greatly enhanced compared to that by a Gaussian beam. The energy density of SC radiation reaches the order of 1µJ/nm in a bandwidth of 258 nm from 559 nm to 817 nm and 0.1 µJ/nm from 500 nm to 559 nm. Furthermore, by checking the polarization distribution of SC in different wavelengths from visible to near-infrared bands, we find that the SC maintains nearly the same polarization distribution as pump pulses. This work provides an effective and convenient way to generate powerful SC vector beams which may facilitate potential applications including optical communication, micro/nano-fabrication, and super-resolution microscopy.
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Poli F, Lægsgaard J. Power scaling of normal-dispersion continuum generation using higher-order modes in microstructured optical fibers. OPTICS LETTERS 2022; 47:698-701. [PMID: 35103711 DOI: 10.1364/ol.448523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 12/13/2021] [Indexed: 06/14/2023]
Abstract
The use of a higher-order HE12-like mode to produce weak normal dispersion over a substantial wavelength range in a microstructured optical fiber is investigated numerically. It is shown that the effective area, and thereby the pulse energy, can in this way be scaled by an order of magnitude compared to using the fundamental mode in a single-mode fiber. Multimode nonlinear simulations indicate that nonlinear mode coupling will not disturb single-mode operation in the HE12 mode at least up to the threshold where polarization modulation instability sets in.
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Ge Z, Zhou ZY, Li Y, Yang C, Liu SK, Shi BS. Fourth-harmonic generation of orbital angular momentum light with cascaded quasi-phase matching crystals. OPTICS LETTERS 2021; 46:158-161. [PMID: 33448977 DOI: 10.1364/ol.406162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 11/21/2020] [Indexed: 06/12/2023]
Abstract
Orbital angular momentum (OAM) light, combined with the nonlinear process to expand the frequency range, has drawn increasing research interest in recent years. Here, we implement the first, to the best of our knowledge, experimental fourth-harmonic generation of OAM light with two cascaded quasi-phase-matching crystals. A Laguerre-Gaussian beam was transmitted through a duplet crystals system and frequency-doubled twice by two separate second-harmonic generation processes, which transduced the frequency of the OAM beam from telecom band to visible band and then to ultraviolet (UV) band. The topological charge of the OAM beam was increased substantially in the cascaded frequency conversion processes. In this experiment, we verify the OAM conservation by utilizing a specially designed interferometer, and the results correspond well with the numerical simulation. This work provides an effective method for the generation of UV OAM beams with high topological charges.
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Davtyan S, Chen Y, Frosz MH, St J Russell P, Novoa D. Robust excitation and Raman conversion of guided vortices in a chiral gas-filled photonic crystal fiber. OPTICS LETTERS 2020; 45:1766-1769. [PMID: 32235994 DOI: 10.1364/ol.383760] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 02/19/2020] [Indexed: 06/11/2023]
Abstract
The unique ring-shaped intensity patterns and helical phase fronts of optical vortices make them useful in many applications. Here we report for the first time, to the best of our knowledge, efficient Raman frequency conversion between vortex modes in a twisted hydrogen-filled single-ring hollow core photonic crystal fiber (SR-PCF). High-fidelity transmission of optical vortices in an untwisted SR-PCF becomes more and more difficult as the orbital angular momentum (OAM) order increases, due to scattering at structural imperfections in the fiber microstructure. In a helically twisted SR-PCF, however, the degeneracy between left- and right-handed versions of the same mode is lifted, with the result that they are topologically protected from such scattering. With launch efficiencies of ${\sim}{75}\% $∼75%, a high damage threshold and broadband guidance, these fibers are ideal for performing nonlinear experiments that require the polarization state and azimuthal order of the interacting modes to be preserved over long distances. Vortex coherence waves of internal molecular motion carrying angular momentum are excited in the gas, permitting the polarization and OAM of the Raman bands to be tailored, even in spectral regions where conventional solid-core waveguides are opaque or susceptible to optical damage.
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Sopalla RP, Wong GKL, Joly NY, Frosz MH, Jiang X, Ahmed G, Russell PSJ. Generation of broadband circularly polarized supercontinuum light in twisted photonic crystal fibers. OPTICS LETTERS 2019; 44:3964-3967. [PMID: 31415523 DOI: 10.1364/ol.44.003964] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 07/12/2019] [Indexed: 06/10/2023]
Abstract
We compare the properties of the broadband supercontinuum (SC) generated in twisted and untwisted solid-core photonic crystal fibers when pumped by circularly polarized 40 picosecond laser pulses at 1064 nm. In the helically twisted fiber, fabricated by spinning the preform during the draw, the SC is robustly circularly polarized across its entire spectrum whereas, in the straight fiber, axial fluctuations in linear birefringence and polarization-dependent nonlinear effects cause the polarization state to vary randomly with the wavelength. Theoretical modelling confirms the experimental results. Helically twisted photonic crystal fibers permit the generation of pure circularly polarized SC light with excellent polarization stability against fluctuations in input power and environmental perturbations.
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