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ABSTRACT: We show that a Bragg grating can act as a phase matching element allowing a continuum pulse to generate light in narrow bandwidth beyond the short wavelength edge determined by fiber dispersion.
01/2770;
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J W Nicholson,
J M Fini,
A M Desantolo,
X Liu,
K Feder,
P S Westbrook,
V R Supradeepa,
E Monberg,
F Dimarcello,
R Ortiz,
C Headley,
D J Digiovanni
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ABSTRACT: We demonstrate scaling of the effective area of higher-order mode, Er-doped fiber amplifiers. Two Er-doped higher-order mode fibers, one with 3800 μm<sup>2</sup> A<sub>eff</sub> in the LP<sub>0,11</sub> mode, and one with 6000 μm<sup>2</sup> effective area in the LP<sub>0,14</sub> mode, are demonstrated. Output beam profiles show clean higher order modes, and S<sup>2</sup> imaging measurements show low extraneous higher order mode content. CW and pulsed amplifier experiments are reported. Nanosecond pulses are amplified to 0.5 mJ pulse energy with 0.5 MW peak power.
Optics Express 10/2012; 20(22):24575-84. · 3.59 Impact Factor
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ABSTRACT: We perform detailed measurements of the higher-order-mode content of a low-loss, hollow-core, photonic-bandgap fiber. Mode content is characterized using Spatially and Spectrally resolved (S<sup>2</sup>) imaging, revealing a variety of phenomena. Discrete mode scattering to core-guided modes are measured at small relative group-delays. At large group delays a continuum of surface modes and core-guided modes can be observed. The LP<sub>11</sub> mode is observed to split into four different group delays with different orientations, with the relative orientations preserved as the mode propagates through the fiber. Cutback measurements allow for quantification of the loss of different individual modes. The behavior of the modes in the low loss region of the fiber is compared to that in a high loss region of the fiber. Finally, a new measurement technique is introduced, the sliding-window Fourier transform of high-resolution transmission spectra of hollow-core fibers, which displays the dependence of HOM content on both wavelength and group delay. This measurement is used to illustrate the HOM content as function of coil diameter.
Optics Express 08/2012; 20(18):20494-505. · 3.59 Impact Factor
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ABSTRACT: We demonstrate a dual-comb spectrometer using stabilized frequency combs spanning 177 to 220 THz (1360 to 1690 nm) in the near infrared. Comb-tooth-resolved measurements of amplitude and phase generate over 4×10(5) individually resolved spectral elements at 100 MHz point spacing and kilohertz-level resolution and accuracy. The signal-to-noise ratio is 100 to 3000 per comb tooth. Doppler-broadened phase and amplitude spectra of CO(2), CH(4), C(2)H(2), and H(2)O in a 30 m multipass cell agree with established spectral parameters, achieving high-resolution measurements with optical bandwidth generally associated with blackbody sources.
Optics Letters 02/2012; 37(4):638-40. · 3.40 Impact Factor
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ABSTRACT: We demonstrate a Raman fiber laser with an operating wavelength of 1480 nm and record output power of 81 W. High-power operation is enabled by a long-period grating used to frustrate backward lasing at the Stokes wavelength in the Yb-doped fiber amplifier. A cascaded Raman fiber with a long-wavelength fundamental mode cutoff enables efficient multiple Stokes scattering from 1117 to 1480 nm while preventing further unwanted scattering to 1590 nm.
Optics Letters 09/2010; 35(18):3069-71. · 3.40 Impact Factor
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ABSTRACT: We demonstrate the first erbium-doped fiber amplifier operating in a single, large-mode area, higher-order mode. A high-power, fundamental-mode, Raman fiber laser operating at 1480 nm was used as a pump source. Using a UV-written, long-period grating, both pump and 1564 nm signal were converted to the LP(0,10) mode, which had an effective area of 2700 microm(2) at 1550 nm. A maximum output power of 5.8 W at 1564 nm with more than 20 dB of gain in a 2.68 m long amplifier was obtained. The mode profile was undistorted at the highest output power.
Optics Express 08/2010; 18(17):17651-7. · 3.59 Impact Factor
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ABSTRACT: Multiple higher-order-modes propagating simultaneously in large-mode-area optical fibers are measured and their relative power levels quantified using spatially and spectrally resolved imaging.
Lasers and Electro-Optics (CLEO) and Quantum Electronics and Laser Science Conference (QELS), 2010 Conference on; 06/2010
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ABSTRACT: It is demonstrated that the lateral resolution of a non-linear scanning multi-photon microscope can be improved significantly by using the light from an LP<sub>02</sub> mode instead of a Gaussian-like beam.
Lasers and Electro-Optics (CLEO) and Quantum Electronics and Laser Science Conference (QELS), 2010 Conference on; 06/2010
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ABSTRACT: A frequency comb is phase-locked to a CW laser with an electro-optic-modulator providing 1.6 MHz feedback bandwidth. Residual phase noise is as low as -94 dBc/Hz, and the comb remained locked under mechanical vibration of up to 1.9 g.
Lasers and Electro-Optics, 2009 and 2009 Conference on Quantum electronics and Laser Science Conference. CLEO/QELS 2009. Conference on; 07/2009
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ABSTRACT: Diffraction limited amplification of the fundamental mode in an Er fiber with 1800 mum<sup>2</sup> effective area is enabled by differential gain induced by launching the pump in the fundamental mode of the fiber.
Lasers and Electro-Optics, 2009 and 2009 Conference on Quantum electronics and Laser Science Conference. CLEO/QELS 2009. Conference on; 07/2009
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Jinkang Lim,
K. Knabe,
Y. Wang,
R. Amezcua-Correa,
F. Couny,
P.S. Light,
F. Benabid,
J.C. Knight,
K.L. Corwin, J.W. Nicholson,
B.R. Washburn
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ABSTRACT: The frequency comb generated by a high repetition frequency erbium-doped fiber ring laser using carbon nanotube saturable absorber is phase-stabilized for the first time. The comb's stability is compared a photonic crystal fiber acetylene reference.
Lasers and Electro-Optics, 2009 and 2009 Conference on Quantum electronics and Laser Science Conference. CLEO/QELS 2009. Conference on; 07/2009
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J.C. Jasapara,
M.J. Andrejco,
A. DeSantolo,
A.D. Yablon,
Z. Vrallyay, J.W. Nicholson,
J.M. Fini,
D.J. DiGiovanni,
C. Headley,
E. Monberg,
F.V. DiMarcello
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ABSTRACT: Diffraction-limited fundamental mode amplification is demonstrated in Er-doped fibers with mode areas ranging from 900 to 1800 mum<sup>2</sup>. The amplifiers are core-pumped with Raman fiber lasers with both signal and pump selectively launched into the fundamental mode. This scheme results in differential gain for the fundamental mode and stabilizes it against mode mixing caused by perturbations in the core. Gains that are greater than 30 dB are demonstrated from a single stage without significant amplified spontaneous emission. The low nonlinearity of the large mode areas enables amplification to high peak powers without resorting to unconventional microstructured or higher order mode fibers.
IEEE Journal of Selected Topics in Quantum Electronics 02/2009; · 3.78 Impact Factor
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ABSTRACT: Spatially and spectrally resolved imaging of mode content in fibers, or more simply, S<sup>2</sup> imaging, is a new measurement technique for analyzing the mode content of large-mode-area (LMA) fibers. It works by spatially resolving the spectral interference that occurs when light in a few-mode fibers scatters into different modes that then propagate with different group delays. A scanning spatial filter in the form of a single-mode fiber probe coupled to an optical spectrum analyzer is utilized to provide both spatial and spectral resolution, and the data are analyzed via the Fourier transform of the optical spectrum. The wealth of data allows for imaging multiple modes simultaneously propagating in the fiber under test as well as quantifying their relative power levels. In addition, the ability to analyze mode images as a function of modal group delay allows distinguishing between discrete scattering at fiber surfaces and distributed scattering that occurs along the length of the LMA fiber. The all-fiber nature of the setup makes the measurement sufficiently stable to measure phase images of the higher order modes (HOMs). Because the method is interferometrically based, even very weak HOMs can be detected.
IEEE Journal of Selected Topics in Quantum Electronics 02/2009; · 3.78 Impact Factor
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ABSTRACT: We demonstrate high-repetition-frequency low-noise passively mode-locked erbium-doped fiber ring lasers using single-walled carbon nanotubes as saturable absorbers. Pulses with a fundamental pulse repetition frequency of 200 MHz and 124-fs width are generated from a ring laser cavity. By substantially simplifying the cavity with a component that integrates multiple functions into a single device, the fundamental pulse repetition frequency could be increased to 447 MHz with pulsewidths of 270 fs.
IEEE Photonics Technology Letters 01/2009; · 2.19 Impact Factor
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C. Headley,
S. Ramachandran,
J. Phillips,
K. Brar,
S. Ghalmi,
M.F. Yan, J.W. Nicholson,
P.W. Wisk,
D. Trevor,
J. Fleming,
E. Monberg,
F. Dimarcello,
R.S. Windeler,
J.M. Fini,
D.J. DiGiovanni
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ABSTRACT: Fiber devices that amplify light propagating in a single fundamental mode face several challenges in extracting ever-increasing powers. Here we explore the advantages and present results showing amplification of light in a single higher order mode.
IEEE Lasers and Electro-Optics Society, 2008. LEOS 2008. 21st Annual Meeting of the; 12/2008
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ABSTRACT: Robust fundamental mode propagation and amplification of picosecond pulses at 1.56 microm wavelength is demonstrated in a core-pumped Er fiber with 1170 microm2 effective area. Record peak power exceeding 120 kW, and 67 nJ pulse energy are achieved before the onset of pulse breakup. A small increase in input pulse energy results in a temporal collapse of the pulse center to 58 fs duration, with peak powers approaching 200 kW.
Optics Express 12/2008; 16(23):18869-74. · 3.59 Impact Factor
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ABSTRACT: We characterize higher-order-mode content in large-mode-area fibres using spatially and spectrally resolved mode imaging. The technique is capable of distinguishing between discrete and distributed scattering of modes.
Optical Communication, 2008. ECOC 2008. 34th European Conference on; 10/2008
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J W Nicholson,
A D Yablon,
M F Yan,
P Wisk,
R Bise,
D J Trevor,
J Alonzo,
T Stockert,
J Fleming,
E Monberg,
F Dimarcello,
J Fini
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ABSTRACT: Femtosecond fiber lasers together with nonlinear fibers are compact, reliable, all-fiber supercontinuum sources. Maintaining an all-fiber configuration, however, necessitates pulse compression in an optical fiber, which can lead to nonlinearities for subhundred femtosecond, nanojoule pulses. In this work we show that using large-mode-area fibers for pulse compression mitigates the nonlinearity, resulting in compressed pulses with significantly reduced satellite pulses. Consequently, supercontinua generated with these pulses are shown to have as much as a 10 dB increase in coherence fringe contrast. By using a hybrid highly nonlinear fiber-photonic crystal fiber, the continuum can be extended to visible wavelengths while still maintaining high coherence.
Optics Letters 10/2008; 33(18):2038-40. · 3.40 Impact Factor
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Laser & Photonics Review 09/2008; 2(6):429 - 448. · 7.39 Impact Factor
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ABSTRACT: A new measurement technique, capable of quantifying the number and type of modes propagating in large-mode-area fibers is both proposed and demonstrated. The measurement is based on both spatially and spectrally resolving the image of the output of the fiber under test. The measurement provides high quality images of the modes that can be used to identify the mode order, while at the same time returning the power levels of the higher-order modes relative to the fundamental mode. Alternatively the data can be used to provide statistics on the level of beam pointing instability and mode shape changes due to random uncontrolled fluctuations of the phases between the coherent modes propagating in the fiber. An added advantage of the measurement is that is requires no prior detailed knowledge of the fiber properties in order to identify the modes and quantify their relative power levels. Because of the coherent nature of the measurement, it is far more sensitive to changes in beam properties due to the mode content in the beam than is the more traditional M(2) measurement for characterizing beam quality. We refer to the measurement as Spatially and Spectrally resolved imaging of mode content in fibers, or more simply as S(2) imaging.
Optics Express 06/2008; 16(10):7233-43. · 3.59 Impact Factor
