White-light Supercontinuum Generation Research Articles

Diffraction-enhanced femtosecond white-light filaments in air

Here we demonstrate filamentation and generation of intense white light supercontinuum from a weakly focused femtosecond Ti:Sapphire laser pulses modified by a partial laser beam blocking by the knife edge. Though the spectral broadening of the filamented laser pulses was observed both in the blue and red sides of the fundamental wavelength, most distinct was the broadband white-light emission covering the whole visible spectral range. The dominant filamentation and supercontinuum generation enhancement mechanism was found to be the diffraction-induced laser beam intensity modification.

Evidence of High-Order Nonlinearities in Supercontinuum White-Light Generation from a Gold Nanofilm

White-light supercontinuum generation can be readily observed when gold nanostructures are irradiated with short pulses of light. It is believed that the nanostructures enhance the optical fields, which facilitates the supercontinuum white-light generation from the surrounding environment or the substrate. Here, we investigate the different nonlinear processes that contribute to the generation of the supercontinuum from plasmonic nanostructures themselves using a technique that isolates the different nonlinear contributions. By exciting a gold nanofilm with a pair of frequency shifted optical frequency combs, we demonstrate multiple modulation frequencies in the supercontinuum. Their dependence on the excitation intensity reveals that the supercontinuum originates from different orders of nonlinear light–matter interactions. This contrasts with the supercontinuum generation by a cascaded third-order optical nonlinear response in traditional dielectric-based white-light sources. The while-light emission fr...

Femtosecond wavelength-tunable OPCPA system based on picosecond fiber laser seed and picosecond DPSS laser pump.

We present a compact and stable femtosecond wavelength-tunable optical parametric chirped pulse amplification (OPCPA) system. A novel OPCPA front-end was constructed using a multi-channel picosecond all-in-fiber source for seeding DPSS pump laser and white light supercontinuum generation. Broadband chirped pulses were parametrically amplified up to 1 mJ energy and compressed to less than 40 fs duration. Pulse wavelength tunability in the range from 680 nm to 930 nm was experimentally demonstrated.

Supercontinuum generation in three-fold symmetry microstructured fibers in visible and infrared spectral regions

We present a series of three fold symmetric silica microstructured fibers for nonlinear application. The fibers are designed to have zero dispersion wavelength far from the pump wavelength. In our fibers a domination of nonlinear effects is precisely controlled by selectively increased three air holes in the vicinity of the core. Our fibers allow for the broadband single mode spectrum generation and the achievement of flat spectra even after changes of fiber dispersion caused by fabrication inaccuracies. Full Text: PDF References S. T. S?rensen, C. Larsen, C. Jakobsen, C. L. Thomsen, and O. Bang, "Single-mode pumped high air-fill fraction photonic crystal fiber taper for high-power deep-blue supercontinuum sources", Opt. Lett, 39, 1097 (2014). CrossRef V. Couderc, P. Leproux, V. Tombelaine, L. Grossard, and A. Barthélémy, "Raman cascade suppression by using wide band parametric conversion in large normal dispersion regime", Opt. Express, 13, 8584 (2005). CrossRef H. E. Heidepriem, S. C. W. Smith, and T. M. Monro, "Suspended nanowires: Fabrication, design and characterization of fibers with nanoscale cores", Opt. Express, 17, 2646 (2009). CrossRef U. M?ller, Y. Yu, I. Kubat, C. R. Petersen, X. Gai, L. Brilland, D. M´echin, C. Caillaud, J. Troles, B. Davies, and O. Bang, "Multi-milliwatt mid-infrared supercontinuum generation in a suspended core chalcogenide fiber", Opt. Express, 17, 3282 (2015). CrossRef I. Shavrin, S. Novotny, and H. Ludvigsen, "Mode excitation and supercontinuum generation in a few-mode suspended-core fiber", Opt. Express, 21, 32141 (2013). CrossRef M. Klimczak, G. Stepniewski, H. Bookey, A. Szolno, R. Stepien, D. Pysz, A. Kar, A. Waddie, M. R. Taghizadeh, and R. Buczynski, "Broadband infrared supercontinuum generation in hexagonal-lattice tellurite photonic crystal fiber with dispersion optimized for pumping near 1560??nm: reply", Opt. Lett. 39, 2241 (2014). CrossRef X. Zhang, X. Zhu, X. Chen, H. Li, J. Peng, N. Dai, and J. Li, "A hollow beam supercontinuum generation by the supermode superposition in a GeO2 doped triangular-core photonic crystal fiber", Opt. Express, 20, 19799 (2012). CrossRef C. Lesvigne, V. Couderc, A. Tonello, P. Leproux, A. Barthélémy, S. Lacroix, F. Druon, P. Blandin, M. Hanna, and P. Georges, "Visible supercontinuum generation controlled by intermodal four-wave mixing in microstructured fiber", Opt. Lett, 32, 2173 (2007). CrossRef S. T. S?rensen, U. M?ller, C. Larsen, P. M. Moselund, C. Jakobsen, J. Johansen, T. V. Andersen, C. L. Thomsen, and O. Bang, "Deep-blue supercontinnum sources with optimum taper profiles ? verification of GAM", Opt. Express, 20, 10635 (2012). CrossRef A. Kudlinski, M. Lelek, B. Barviau, L. Audry, and A. Mussot, "Efficient blue conversion from a 1064 nm microchip laser in long photonic crystal fiber tapers for fluorescence microscopy", Opt. Express, 18, 16640 (2010). CrossRef A. Kudlinski, G. Bouwmans, O. Vanvincq, Y. Quiquempois, A. Le Rouge, L. Bigot, G. Mélin, and A. Mussot, "White-light cw-pumped supercontinuum generation in highly GeO2 -doped-core photonic crystal fibers", Opt. Lett. 34, 3631 (2009). CrossRef A. Kudlinski, V. Pureur, G. Bouwmans, and A. Mussot, "Experimental investigation of combined four-wave mixing and Raman effect in the normal dispersion regime of a photonic crystal fiber", Opt. Lett. 33, 2488 (2008). CrossRef Z. Holdynski, M. Napierala, P. Mergo, and T. Nasilowski, "Experimental Investigation of Supercontinuum Generation in Photonic Crystal Fibers Pumped With Sub-ns Pulses", J. Lightwave Technol., 33, 2106 (2015). CrossRef U. M?ller, S. T. S?rensen, C. Larsen, P. M. Moselund, C. Jakobsen ,J. Johansen, C. L. Thomsen, O. Bang, "Optimum PCF tapers for blue-enhanced supercontinuum sources", Opt. Fiber Technol., 18, 3104 (2012). CrossRef

Pulse fidelity control in a 20-μJ sub-200-fs monolithic Yb-fiber amplifier

We discuss nonlinearity management versus energy scalability and compressibility in a three-stage monolithic 100-kHz repetition rate Yb-fiber amplifier designed as a driver source for the generation and tunable parametric amplification of a carrier-envelope phase stable white-light supercontinuum.

Enhanced Super continuum generation in water in the presence of ultra dilute solutions

Intense ultrashort laser beam, after propagation through a transparent medium (water in this work), experiences self-focusing, thereby increasing the intensities in localized area to such high values so as to induce nonlinear optical effects like the generation of white light super-continuum and multi-photon absorption. We have carried out experiments for measuring super-continuum generation in water that contains ultra dilute solutes (of ethanol). Our observations of generation of super-continuum spectra in various solutes indicate that our measurements are able to make a distinction between normal water and water mixed with such ultra-dilute solutes i.e. Homoeopathic medicines.

White light supercontinuum generation in a Y-shaped microstructured tapered fiber pumped at 1064 nm

We report the generation of supercontinuum in a Ge-doped Y-shape tapered fiber pumped at 1064 nm in the ns pump regime. The taper was designed to have long taper transitions and a taper waist with a core diameter of 0.9 mum. The large air-filling fraction and diameter of the air-hole microstructure reduces the confinement loss at long wavelengths so, enabling the extension of the spectrum to longer wavelengths. Along the taper transition the zero-dispersion wavelength decreases as the diameter of the taper becomes smaller. The spectral components generated along the taper transition pump the taper waist, enhancing the generation of short wavelengths. A flat spectrum spanning from 420 nm to 1850 nm is reported.

Continuum generation in photonic crystal fibres by multi-wavelength amplified sub-nanosecond light pulses

We report the results of experimental study of a white-light supercontinuum generation in single-mode air-silica microstructured fibres under sub-nanosecond single and dual wavelength pumping. We show that simultaneous excitation of the microstuctured fibre in its normal and anomalous dispersion regimes using the fundamental and second harmonic signals of a passively Q-switched microchip laser results in extension of the spectral range covered by homogeneous supercontinuum to the UV range up to 375 nm. Keywords: supercontinuum, photonic crystal fibre

White-light cw-pumped supercontinuum generation in highly GeO_2-doped-core photonic crystal fibers

GeO(2)-doped-core photonic crystal fibers show greatly enhanced Kerr and Raman responses with respect to pure silica without any significant modification of the group-velocity dispersion curve. We show that such fibers allow a significant improvement of cw-pumped supercontinuum generation. We report for the first time to our knowledge the generation of a white-light cw-pumped supercontinuum spanning from 470 nm to more than 1750 nm.

Ten years of nonlinear optics in photonic crystal fibre

The year 2009 marks the tenth anniversary of the first report of white-light supercontinuum generation in photonic crystal fibre. This result had a tremendous impact on the field of nonlinear fibre optics and continues to open up new horizons in photonic science. Here we provide a concise and critical summary of the current state of nonlinear optics in photonic crystal fibre, identifying some of the most important and interesting recent developments in the field. We also discuss several emerging research directions and point out links with other areas of physics that are now becoming apparent.

Resonant Optical Antennas

We have fabricated nanometer-scale gold dipole antennas designed to be resonant at optical frequencies. On resonance, strong field enhancement in the antenna feed gap leads to white-light supercontinuum generation. The antenna length at resonance is considerably shorter than one-half the wavelength of the incident light. This is in contradiction to classical antenna theory but in qualitative accordance with computer simulations that take into account the finite metallic conductivity at optical frequencies. Because optical antennas link propagating radiation and confined/enhanced optical fields, they should find applications in optical characterization, manipulation of nanostructures, and optical information processing.

White-light supercontinuum generation in normally dispersive optical fiber using original multi-wavelength pumping system

We report on the experimental demonstration of a white-light supercontinuum generation in normally dispersive singlemode air-silica microstructured fiber. We demonstrate that the simultaneous excitation of the microstuctured fiber in its normal and anomalous dispersion regimes using the fundamental and second harmonic signals of a passively Q-switched microchip laser leads to a homogeneous supercontinuum in the visible range. This pumping scheme allows the suppression of the cascaded Raman effect predominance in favor of an efficient spectrum broadening induced by parametric phenomena. A flat supercontinuum extended from 400 to 700 nm is achieved.

Sub femto-joule sensitive single-shot OPA-XFROG and its application in study of white-light supercontinuum generation

We report a new design of single-shot cross-correlation frequency-resolved optical gating (XFROG) with sub femto-joule sensitivity for complete field characterization of ultrashort optical pulse using a 400- nm-pumped type-I noncollinear optical parametric amplifier. Optical parametric gain as high as 10(8) with 0.8-0.9 femto-joules sensitivity had been demonstrated with an un-cooled CCD in this study. The experimental FROG traces have been successfully retrieved with an error no worse than 0.0014. The device had been to be useful for studying the generation mechanism of white-light supercontinuum (WLS).

Simulation of femtosecond pulse propagation in air

We present numerical simulations of the propagation of intense spatio-temporal fields propagating in air. Characteristic parameters of the propagation like peak intensities, plasma densities and diameters of the plasma channels are obtained. The evolution of the spectral content of the pulses is investigated and, in agreement with recent experiments, white-light supercontinuum generation is observed. We show in which areas of the pulse the supercontinuum is generated and conclude that self-phase modulation is responsible for the spectral broadening. Furthermore we investigate azimuthal instabilities of intense rotationally symmetric pulsed beams propagating in air. Although the spatial-temporal evolution of the field is strongly influenced by the onset of plasma generation, the instabilities are basically caused by the Kerr effect. We conclude that calculations assuming rotational symmetry become unrealistic due to the fast growth of azimuthal instabilities in the focal region.

White-light supercontinuum generation with 60-ps pump pulses in a photonic crystal fiber

The generation of a spatially single-mode white-light supercontinuum has been observed in a photonic crystal fiber pumped with 60-ps pulses of subkilowatt peak power. The spectral broadening is identified as being due to the combined action of stimulated Raman scattering and parametric four-wave-mixing generation, with a negligible contribution from the self-phase modulation of the pump pulses. The experimental results are in good agreement with detailed numerical simulations. These findings demonstrate that ultrafast femtosecond pulses are not needed for efficient supercontinuum generation in photonic crystal fibers.