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Van Le H, Hoang VT, Stępniewski G, Le Canh T, Thi Minh NV, Kasztelanic R, Klimczak M, Pniewski J, Dinh KX, Heidt AM, Buczyński R. Low pump power coherent supercontinuum generation in heavy metal oxide solid-core photonic crystal fibers infiltrated with carbon tetrachloride covering 930-2500 nm. OPTICS EXPRESS 2021; 29:39586-39600. [PMID: 34809320 DOI: 10.1364/oe.443666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 11/04/2021] [Indexed: 06/13/2023]
Abstract
All-normal dispersion supercontinuum (ANDi SC) generation in a lead-bismuth-gallate glass solid-core photonic crystal fiber (PCF) with cladding air-holes infiltrated with carbon tetrachloride (CCl4) is experimentally investigated and numerically verified. The liquid infiltration results in additional degrees of freedom that are complimentary to conventional dispersion engineering techniques and that allow the design of soft-glass ANDi fibers with an exceptionally flat near-zero dispersion profile. The unique combination of high nonlinearity and low normal dispersion enables the generation of a coherent, low-noise SC covering 0.93-2.5 µm requiring only 12.5 kW of pump peak power delivered by a standard ultrafast erbium-fiber laser with 100 MHz pulse repetition rate (PRR). This is a much lower peak power level than has been previously required for the generation of ANDi SC with bandwidths exceeding one octave in silica- or soft-glass fibers. Our results show that liquid-composite fibers are a promising pathway for scaling the PRR of ANDi SC sources by making the concept accessible to pump lasers with hundreds of megahertz of gigahertz PRR that have limited peak power per pulse but are often required in applications such as high-speed nonlinear imaging, optical communications, or frequency metrology. Furthermore, due to the overlap of the SC with the major gain bands of many rare-earth fiber amplifiers, our source could serve as a coherent seed for low-noise ultrafast lasers operating in the short-wave infrared spectral region.
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Heidt AM, Modupeh Hodasi J, Rampur A, Spangenberg DM, Ryser M, Klimczak M, Feurer T. Low noise all-fiber amplification of a coherent supercontinuum at 2 µm and its limits imposed by polarization noise. Sci Rep 2020; 10:16734. [PMID: 33028876 PMCID: PMC7541617 DOI: 10.1038/s41598-020-73753-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 09/17/2020] [Indexed: 11/22/2022] Open
Abstract
We report a low noise, broadband, ultrafast Thulium/Holmium co-doped all-fiber chirped pulse amplifier, seeded by an Erbium-fiber system spectrally broadened via coherent supercontinuum generation in an all-normal dispersion photonic crystal fiber. The amplifier supports a − 20 dB bandwidth of more than 300 nm and delivers high quality 66 fs pulses with more than 70 kW peak power directly from the output fiber. The total relative intensity noise (RIN) integrated from 10 Hz to 20 MHz is 0.07%, which to our knowledge is the lowest reported RIN for wideband ultrafast amplifiers operating at 2 µm to date. This is achieved by eliminating noise-sensitive anomalous dispersion nonlinear dynamics from the spectral broadening stage. In addition, we identify the origin of the remaining excess RIN as polarization modulational instability (PMI), and propose a route towards complete elimination of this excess noise. Hence, our work paves the way for a next generation of ultra-low noise frequency combs and ultrashort pulse sources in the 2 µm spectral region that rival or even outperform the excellent noise characteristics of Erbium-fiber technology.
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Affiliation(s)
- Alexander M Heidt
- Institute of Applied Physics, University of Bern, Sidlerstrasse 5, 3012, Bern, Switzerland.
| | | | - Anupamaa Rampur
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland
| | | | - Manuel Ryser
- Institute of Applied Physics, University of Bern, Sidlerstrasse 5, 3012, Bern, Switzerland
| | - Mariusz Klimczak
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland
| | - Thomas Feurer
- Institute of Applied Physics, University of Bern, Sidlerstrasse 5, 3012, Bern, Switzerland
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Nguyen HPT, Tuan TH, Xing L, Matsumoto M, Sakai G, Suzuki T, Ohishi Y. Supercontinuum generation in a chalcogenide all-solid hybrid microstructured optical fiber. OPTICS EXPRESS 2020; 28:17539-17555. [PMID: 32679961 DOI: 10.1364/oe.394968] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 05/04/2020] [Indexed: 06/11/2023]
Abstract
We report the fabrication of a chalcogenide all-solid hybrid microstructured optical fiber and its application in supercontinuum generation for the first time, to the best of our knowledge. The fiber possesses all-normal and flattened chromatic dispersion, making it highly potential for broad and coherent supercontinuum generation. By pumping the fiber with a femtosecond laser at 3, 4, and 5 μm, broad supercontinua with good spectral flatness are generated. The broadest SC spectrum extending from 2.2 to 10 μm at -20 dB level was obtained when the fiber was pumped at 5 μm with an input power of 3.9 mW.
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Rampur A, Spangenberg DM, Stępniewski G, Dobrakowski D, Tarnowski K, Stefańska K, Paździor A, Mergo P, Martynkien T, Feurer T, Klimczak M, Heidt AM. Temporal fine structure of all-normal dispersion fiber supercontinuum pulses caused by non-ideal pump pulse shapes. OPTICS EXPRESS 2020; 28:16579-16593. [PMID: 32549477 DOI: 10.1364/oe.392871] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 04/21/2020] [Indexed: 06/11/2023]
Abstract
We experimentally investigate the spectro-temporal characteristics of coherent supercontinuum (SC) pulses generated in several implementations of silica and soft-glass all-normal dispersion (ANDi) photonic crystal fibers optimized for pumping with Erbium (Er):fiber femtosecond laser technology. We characterize the resulting SC using time-domain ptychography, which is especially suitable for the measurement of complex, spectrally broadband ultrashort pulses. The measurements of the ANDi SC pulses reveal intricate pulse shapes, considerable temporal fine structure, and oscillations on time scales of < 25 femtoseconds, which differ from the smoothness and simplicity of temporal profiles obtained in numerical simulations and observed in previous experiments. We link the measured complex features to temporal sub-structures of the pump pulse, such as pre- and post-pulses and low-level pedestals, which are common in high pulse energy ultrafast Er:fiber systems. We also observe spectro-temporal structures consistent with incoherent noise amplification in weakly birefringent fiber samples. Our results highlight the importance of the pump source and polarization-maintaining (PM) fibers for high-quality SC generation and have practical relevance for many ultrafast photonics applications employing ANDi fiber-based SC sources.
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Abstract
AbstractWe report on near-infrared supercontinuum generation in a submeter-long single-mode, nanostructured core fiber. The fiber core is composed of few thousand pure silica and germanium-doped silica glass nanorods with diameter of 200 nm each. The nanorods’ distribution is calculated based on the Maxwell–Garnett effective medium approach to mimic effective parabolic refractive index distribution in the fiber core. The standard stack-and-draw method was used to scale down the fiber structure and obtain subwavelength nanorods in the core. Size and distribution of individual nanorods are essential to determine modal and dispersion properties of the fiber without assistance of air holes in the fiber cladding. We study supercontinuum generation performance in this nanostructured core fiber pumping with low-cost microchip laser operating at 1550 nm with 1 ns pulse length and pulse energy of 0.4 µJ. A modulation instability-driven supercontinuum is generated in the fiber, covering a wavelength span of 1400–2300 nm. Due to possibility of dispersion engineering and all-solid structure the nanostructured fibers offer new possibilities for development of low-cost all-fiber supercontinuum light sources for the near-infrared range and cascaded ultrabroadband supercontinuum all-fiber systems.
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Engelsholm RD, Bang O. Supercontinuum noise reduction by fiber undertapering. OPTICS EXPRESS 2019; 27:10320-10331. [PMID: 31045176 DOI: 10.1364/oe.27.010320] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We demonstrate that the Relative Intensity Noise (RIN) of a supercontinuum source can be significantly reduced using the new concept of undertapering, where the fiber is tapered to a diameter that is smaller than the diameter that gives the shortest blue edge, which is typically regarded as the optimum. We show that undertapering allows to control the second zero dispersion wavelength and use it as a soliton barrier to stop the redshifting solitons at a pre-defined wavelength, and thereby strongly reduce the RIN. We demonstrate how undertapering can reduce the spectrally averaged RIN in the optical coherence tomography bands, 500-800nm and 1150-1450nm, by more than a factor two.
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Huang C, Liao M, Bi W, Li X, Wang L, Xue T, Zhang L, Chen D, Hu L, Fang Y, Gao W. Asterisk-shaped microstructured fiber for an octave coherent supercontinuum in a sub-picosecond region. OPTICS LETTERS 2018; 43:486-489. [PMID: 29400821 DOI: 10.1364/ol.43.000486] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 12/22/2017] [Indexed: 06/07/2023]
Abstract
We selected two thermally matched silicate glasses with fair refractive index contrast and developed an asterisk-shaped all-solid microstructured optical fiber. The fiber presents a low, ultra-flat, and all-normal dispersion in a wide wavelength range, allowing for the generation of an octave-spanning coherent supercontinuum (SC) in a 20 dB dynamic range with 0.5 ps pump pulses at 1.55 μm. This result improves pump pulse duration that is only ∼100 fs, related to the broadband and highly coherent SC generation in fibers with all-normal dispersion. This enables broadband SC sources with all-fiber, high-power, and highly coherent properties.
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Tarnowski K, Martynkien T, Mergo P, Poturaj K, Anuszkiewicz A, Béjot P, Billard F, Faucher O, Kibler B, Urbanczyk W. Polarized all-normal dispersion supercontinuum reaching 2.5 µm generated in a birefringent microstructured silica fiber. OPTICS EXPRESS 2017; 25:27452-27463. [PMID: 29092218 DOI: 10.1364/oe.25.027452] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 10/16/2017] [Indexed: 06/07/2023]
Abstract
We demonstrate a polarized all-normal dispersion supercontinuum generated in a birefringent silica microstructured fiber spanning beyond 2.5 µm. To our knowledge, this is the spectra reaching the furthest in mid-infrared ever generated in normal dispersion silica fibers. The generation process was studied experimentally and numerically with 70 fs pump pulses operating at different wavelengths on short propagation distances of 48 mm and 122 mm. The all-normal operation was limited by the zero-dispersion wavelength at 2.56 µm and spectral broadening was stopped by OH absorption peak at 2.72 µm. We identified the asymmetry between propagation in both polarization axes and showed that pumping along a slow fiber axis is beneficial for a higher degree of polarization. Numerical simulations of the generation process conducted by solving the generalized nonlinear Schrödinger equation (NLSE) and coupled NLSEs system showed good agreement with experimental spectra.
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