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Liu Y, Zhao Y, Lyngsø J, You S, Wilson WL, Tu H, Boppart SA. Suppressing Short-term Polarization Noise and Related Spectral Decoherence in All-normal Dispersion Fiber Supercontinuum Generation. JOURNAL OF LIGHTWAVE TECHNOLOGY : A JOINT IEEE/OSA PUBLICATION 2015; 33:1814-1820. [PMID: 26166939 PMCID: PMC4495961 DOI: 10.1109/jlt.2015.2397276] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The supercontinuum generated exclusively in the normal dispersion regime of a nonlinear fiber is widely believed to possess low optical noise and high spectral coherence. The recent development of flattened all-normal dispersion fibers has been motivated by this belief to construct a general-purpose broadband coherent optical source. Somewhat surprisingly, we identify a large short-term polarization noise in this type of supercontinuum generation that has been masked by the total-intensity measurement in the past, but can be easily detected by filtering the supercontinuum with a linear polarizer. Fortunately, this hidden intrinsic noise and the accompanied spectral decoherence can be effectively suppressed by using a polarization-maintaining all-normal dispersion fiber. A polarization-maintaining coherent supercontinuum laser is thus built with a broad bandwidth (780-1300 nm) and high spectral power (~1 mW/nm).
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Affiliation(s)
- Yuan Liu
- Biophotonics Imaging Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Youbo Zhao
- Biophotonics Imaging Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Jens Lyngsø
- NKT Photonics A/S, Blokken 84, 3460 Birkerød, Denmark
| | - Sixian You
- Biophotonics Imaging Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - William L. Wilson
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Haohua Tu
- Biophotonics Imaging Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Stephen A. Boppart
- Biophotonics Imaging Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Tu H, Boppart SA. Coherent fiber supercontinuum for biophotonics. LASER & PHOTONICS REVIEWS 2013; 7:10.1002/lpor.201200014. [PMID: 24358056 PMCID: PMC3864867 DOI: 10.1002/lpor.201200014] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 07/05/2012] [Indexed: 05/17/2023]
Abstract
Biophotonics and nonlinear fiber optics have traditionally been two independent fields. Since the discovery of fiber-based supercontinuum generation in 1999, biophotonics applications employing incoherent light have experienced a large impact from nonlinear fiber optics, primarily because of the access to a wide range of wavelengths and a uniform spatial profile afforded by fiber supercontinuum. However, biophotonics applications employing coherent light have not benefited from the most well-known techniques of supercontinuum generation for reasons such as poor coherence (or high noise), insufficient controllability, and inadequate portability. Fortunately, a few key techniques involving nonlinear fiber optics and femtosecond laser development have emerged to overcome these critical limitations. Despite their relative independence, these techniques are the focus of this review, because they can be integrated into a low-cost portable biophotonics source platform. This platform can be shared across many different areas of research in biophotonics, enabling new applications such as point-of-care coherent optical biomedical imaging.
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Affiliation(s)
- Haohua Tu
- Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Stephen A Boppart
- Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Liu Y, King MD, Tu H, Zhao Y, Boppart SA. Broadband nonlinear vibrational spectroscopy by shaping a coherent fiber supercontinuum. OPTICS EXPRESS 2013; 21:8269-75. [PMID: 23571917 PMCID: PMC3641023 DOI: 10.1364/oe.21.008269] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 03/08/2013] [Accepted: 03/19/2013] [Indexed: 05/26/2023]
Abstract
Vibrational spectroscopy has been widely applied in different fields due to its label-free chemical-sensing capability. Coherent anti-Stokes Raman scattering (CARS) provides stronger signal and faster acquisition than spontaneous Raman scattering, making it especially suitable for molecular imaging. Coherently-controlled single-beam CARS simplifies the conventional multi-beam setup, but the vibrational bandwidth and non-trivial spectrum retrieval have been limiting factors. In this work, a coherent supercontinuum generated in an all-normal-dispersion nonlinear fiber is phase-shaped within a narrow bandwidth for broadband vibrational spectroscopy. The Raman spectra can be directly retrieved from the CARS measurements, covering the fingerprint regime up to 1750 cm(-1). The retrieved spectra of several chemical species agree with their spontaneous Raman data. The compact fiber supercontinuum source offers broad vibrational bandwidth with high stability and sufficient power, showing the potential for spectroscopic imaging in a wide range of applications.
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Affiliation(s)
- Yuan Liu
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801,
USA
| | - Matthew D. King
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801,
USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801,
USA
- Department of Internal Medicine, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801,
USA
| | - Haohua Tu
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801,
USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801,
USA
- Department of Internal Medicine, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801,
USA
| | - Youbo Zhao
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801,
USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801,
USA
- Department of Internal Medicine, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801,
USA
| | - Stephen A. Boppart
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801,
USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801,
USA
- Department of Internal Medicine, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801,
USA
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Liu Y, Tu H, Boppart SA. Wave-breaking-extended fiber supercontinuum generation for high compression ratio transform-limited pulse compression. OPTICS LETTERS 2012; 37:2172-4. [PMID: 22739845 PMCID: PMC3699325 DOI: 10.1364/ol.37.002172] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Wave-breaking often occurs when a short intense optical pulse propagates in a long normally dispersive optical fiber. This effect has conventionally been avoided in fiber (super-)continuum-based pulse compression because the accumulated frequency chirp of the output pulse cannot be fully compensated by a standard prism (or grating) pair. Thus, the spectral extending capability of the wave-breaking has not been utilized to shorten the compressed pulse. We demonstrate that wave-breaking-free operation is not necessary if a 4f pulse shaper-based compressor is employed to remove both the linear and nonlinear chirp of the output pulse. By propagating a 180 fs (FWHM) input pulse in a nonlinear photonic crystal fiber beyond the wave-breaking limit, we compress the wave-breaking-extended supercontinuum output pulse to the bandwidth-limited duration of 6.4 fs (FWHM). The combination of high compression ratio (28×) and short pulse width represents a significant improvement over that attained in the wave-breaking-free regime.
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Affiliation(s)
- Yuan Liu
- Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Haohua Tu
- Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Corresponding author:
| | - Stephen A. Boppart
- Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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Liu Y, Tu H, Benalcazar WA, Chaney EJ, Boppart SA. Multimodal Nonlinear Microscopy by Shaping a Fiber Supercontinuum From 900 to 1160 nm. IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS : A PUBLICATION OF THE IEEE LASERS AND ELECTRO-OPTICS SOCIETY 2012; 18:10.1109/JSTQE.2011.2168559. [PMID: 24187481 PMCID: PMC3812947 DOI: 10.1109/jstqe.2011.2168559] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Nonlinear microscopy has become widely used in biophotonic imaging. Pulse shaping provides control over nonlinear optical processes of ultrafast pulses for selective imaging and contrast enhancement. In this study, nonlinear microscopy, including two-photon fluorescence, second harmonic generation, and third harmonic generation, was performed using pulses shaped from a fiber supercontinuum (SC) spanning from 900 to 1160 nm. The SC generated by coupling pulses from a Yb:KYW pulsed laser into a photonic crystal fiber was spectrally filtered and compressed using a spatial light modulator. The shaped pulses were used for nonlinear optical imaging of cellular and tissue samples. Amplitude and phase shaping the fiber SC offers selective and efficient nonlinear optical imaging over a broad bandwidth with a single-beam and an easily tunable setup.
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Affiliation(s)
- Yuan Liu
- Department of Bioengineering, Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA ( )
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Tu H, Liu Y, Liu X, Turchinovich D, Lægsgaard J, Boppart SA. Nonlinear polarization dynamics in a weakly birefringent all-normal dispersion photonic crystal fiber: toward a practical coherent fiber supercontinuum laser. OPTICS EXPRESS 2012; 20:1113-28. [PMID: 22274457 PMCID: PMC3402041 DOI: 10.1364/oe.20.001113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Dispersion-flattened dispersion-decreased all-normal dispersion (DFDD-ANDi) photonic crystal fibers have been identified as promising candidates for high-spectral-power coherent supercontinuum (SC) generation. However, the effects of the unintentional birefringence of the fibers on the SC generation have been ignored. This birefringence is widely present in nonlinear non-polarization maintaining fibers with a typical core size of 2 µm, presumably due to the structural symmetry breaks introduced in the fiber drawing process. We find that an intrinsic form-birefringence on the order of 10(-5) profoundly affects the SC generation in a DFDD-ANDi photonic crystal fiber. Conventional simulations based on the scalar generalized nonlinear Schrödinger equation (GNLSE) fail to reproduce the prominent observed features of the SC generation in a short piece (9-cm) of this fiber. However, these features can be qualitatively or semi-quantitatively understood by the coupled GNLSE that takes into account the form-birefringence. The nonlinear polarization effects induced by the birefringence significantly distort the otherwise simple spectrotemporal field of the SC pulses. We therefore propose the fabrication of polarization-maintaining DFDD-ANDi fibers to avoid these adverse effects in pursuing a practical coherent fiber SC laser.
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Affiliation(s)
- Haohua Tu
- Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
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