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Frontières et défis de l'optique non-linéaire nouveaux guides d’ondes, nouvelles non linéarités, nouvelles directions … John Dudley CNRS Institut FEMTO-ST Université de Franche-Comté Besançon, France Workshop INSIS - Optique électromagnétique Mardi 2 décembre 2014 Nonlinear optics and lasers are natural partners The high power and spatial coherence of laser light enabled the study of the nonlinear response of light to optical fields 1960 1961 (the first evidence of the second harmonic was removed as a speck of dirt) Nonlinear optics and lasers are natural partners The high power and spatial coherence of laser light enabled the study of the nonlinear response of light to optical fields 1960 1961 (the first evidence of the second harmonic was removed as a speck of dirt) The uses of nonlinear optics Does this mean that nonlinear optics has only very few applications? E. Garmire, Nonlinear Optics in Daily Life, Optics Express 21 30532 (2013) The uses of nonlinear optics Nonlinear Optics Fundamental Science Source Development Applications in Materials Information Technology etc … New Wavelengths Machining Amplifiers Ultrafast lasers Spectroscopy Soliton-like pulses Frequency Combs Analytical Tools Sensors … … … Nonlinearity is often embedded within optical systems and applications E. Garmire, Nonlinear Optics in Daily Life, Optics Express 21 30532 (2013) A selection of topics • Where is nonlinear optics useful today? • • • Supercontinuum and applications Telecommunications Source development Other areas of physics • Towards true nanoscale nonlinear optics Nanoscale material processing Proof of principle results Challenges • Where is nonlinear optics useful today? 1960’s saw low-loss optical waveguide development • Reliable techniques for fabricating small-core waveguides allows tailored linear guidance (dispersion) and controlled nonlinear interactions Submarine cables www.submarinecablemap.com The need for disruptive photonic technologies Bandwidth Catastrophe Solution: all-optical integration and functionality Basic communication system SOURCE MODULATOR DETECTOR Propagation control New optical waveguides Nonlinear functionalities Optical response A Hype Cycle of Nonlinear Optics Low loss waveguides, new materials Nonlinear Solutions to every problem Peak of Hype RESEARCH Practical sources Alternative solutions Hard Work, Realism Nonlinearity Trigger Limited real world use Depths of Despair TIME … A Hype Cycle of Nonlinear Optics Low loss waveguides, new materials Nonlinear Solutions to every problem Peak of Hype New Trigger RESEARCH Practical sources Alternative solutions Hard Work, Realism Nonlinearity Trigger Limited real world use Depths of Despair TIME New waveguides enable other possibilities The mid 1990’s saw the development of micro (then nano) structured waveguides with the ability to engineer nonlinearity and dispersion Nonlinear effects now observed using a wider range of sources Match wavelengths of source & waveguide zero dispersion The effects observed were unexpected … The effects observed were unexpected … (Note on history) • Russell’s initial idea was to create a photonic bandgap guidance mechanism in contrast to the refractive index guidance mechanism 1991 • The first fibers they tried to make failed to show a photonic bandgap, but they tested them anyway, and discovered the fact that the microstructure provided new possibilities to engineer refractive index guidance Nonlinear pulse propagation Polarization contains linear and nonlinear components In fibres we are concerned with nonlinear polarization from c(3) Neglecting third harmonic generation yields : intensity-dependent refractive index n(I) = n0 + n2 I Modelling the supercontinuum is more complex We use a generalized nonlinear Schrödinger equation (NLSE) Linear dispersion Self-steepening Physics: NLSE + perturbations Three main processes Soliton ejection Raman – shift to long l Radiation – shift to short l SPM, FWM, Raman Modelling agrees with experiment !! We use a generalized nonlinear Schrödinger equation (NLSE) Linear dispersion Self-steepening SPM, FWM, Raman Three main processes Soliton ejection Raman – shift to long l Radiation – shift to short l Spectrum (20 dB/div) Physics: NLSE + perturbations Output Spectra Experiment Simulation Wavelength (nm) Ultrafast nonlinear fiber optics Basic description of ultrashort pulses An octave-spanning spectrum allows comb position to be readily stabilized We can bridge the gap between a known optical frequency locked to definition of the second and any optical frequency Frequency combs find very wide use Example: planetary discovery Periodic Doppler shift of stellar spectral lines is perturbed by planetary motion Astrocombs measure radial velocity changes of ~ 10 cm/s Who would have predicted this ? Example: broadband light source Molecular fingerprinting Human breath analysis S. Diddams et al. Nature 445, 627 (2007) M. J. Thorpe et al. Opt. Express 16, 2387 (2008) Supercontinuum applied in Terabit/s telecommunications Here, the nonlinear optics is enabling but the real breakthrough is the system D. Hillerkuss et al. Supercontinuum is used for broad spectrum for spectral slicing and OFDM Materials New materials enable progress to-mid infrared Organic fingerprint region – gas sensing, medicine, food analysis etc Nonlinear optics in gas-filled fibres enables UV The ability to pressure-tune dispersion in hollow core fibres enables gas-phase nonlinear optics Hollow-core photonic crystal fibres for gas-based nonlinear optics, Nat Photon 8, 278–286 (2014) Nonlinear optics is central to fs source development Exploiting and managing nonlinearity is critical in the design of a wide range of femtosecond sources in many different application regimes W Sibbett et al. The development and application of femtosecond laser systems Optics Express Focus Issue on Modular Ultrafast Lasers 20 6989-7001 (2012) Nonlinear optics is central to fs source development Nonlinear saturable absorption is a key component of pulsed lasers Optical “toy models” for other physical systems Nonlinear wave evolution in fiber and on deep water are described by the same nonlinear propagation model Rogue waves – rare and extreme surface waves Rogue Waves are extreme events appearing seemingly from nowhere • Ocean Waves • Optics 1974 1995 Kherif et al. Rogue Waves in the Ocean, Springer (2009) Dudley et al. Nature Photonics 8, 755-764 (2014) Now influencing research in fluid mechanics Rogue Waves in a Water Tank Chabchoub et al. Phys. Rev. Lett. 106 204502 (2011) • Towards truly nanoscale nonlinear optics Nonlinear optics of permanent material modification Gatass, R. and Mazur, E. Nature Photonics 2,219 (2008) Gaussian beams cannot penetrate deeply in materials Tradeoff between interaction length and intensity Gaussian beams have an unavoidable tradeoff between interaction length and focal spotsize and power density Femtosecond ablation for machining extended channels is a difficult technology White,Y. et al, Opt. Express 16,14411 (2008) Enhanced interaction lengths also possible in free space The spatial phase of femtosecond Gaussian beams can be tailored to yield important classes of non-diffracting and accelerating beams Non-diffracting Bessel Beams J. Durnin et al. Phys. Rev. Lett. 58 1499 (1987) Accelerating Airy Beams M. V. Berry and N. L. Balazs Am. J. Phys. 47 264 (1979) G. A. Siviloglou et al. Phys. Rev. Lett. 99 213901 (2007) New possibilities for micro and nano structuring High aspect ratio channels using Bessel beams Advanced surface machining using accelerating and vortex beams Graphene 10 mm Expt High aspect ratio nanochannels Sending fs pulses in circles Machining diamond and silicon Vortex Bessel beams in graphene M. Bhuyan et al. Appl. Phys. Lett. 97 081102 (2010) F. Courvoiser et al. Opt. Lett. (April 2012) A. Mathis et al. Appl. Phys. Lett. 101, 071110 (2012) B. Wetzel et al. Appl. Phys. Lett. 103, 241111 (2013) New materials enable progress to nanoscale Theoretical challenges Major Linear dispersion 1. 2. 3. 4. 5. Input pulse is a high-order soliton Perturbation due to proximity to ZDW Break up into fundamental solitons Soliton dynamics - Raman self-frequency shift (RED) Soliton dynamics - Dispersive wave generation (BLUE) Minor SPM, FWM, Raman Characterisation challenge Time resolved near-field microscopy needs to become an easy technology! Metamaterials, plasmonics Enhanced SHG Nonlinear phase modulation Fano resonances Bistability Metamaterial NLSE Allan Boardman Opt. Commun. 283 1585 (2010) Solitons Parametric amplification Raman scattering Phase conjugation Wavelength conversion Where are we today with nonlinear nanophotonics? Low loss waveguides, new materials Nonlinear Solutions to every problem Peak of Hype RESEARCH Practical sources Alternative solutions Hard Work, Realism Nonlinearity Trigger Limited real world use Depths of Despair TIME …