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 Mardi 2 décembre 2014Workshop INSIS - Optique électromagnétique

The high power and spatial coherence of laser light enabled the study of the nonlinear response of light to optical fields (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 (the first evidence of the second harmonic was removed as a speck of dirt) Nonlinear optics and lasers are natural partners

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 (2013)

Nonlinearity is often embedded within optical systems and applications Nonlinear Optics Fundamental Science Source Development Applications in Materials Information Technology etc New Wavelengths Ultrafast lasers Frequency Combs Machining Spectroscopy Analytical Tools Amplifiers Soliton-like pulses Sensors The uses of nonlinear optics … … … … E. Garmire, Nonlinear Optics in Daily Life, Optics Express (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?

Reliable techniques for fabricating small-core waveguides allows tailored linear guidance (dispersion) and controlled nonlinear interactions 1960’s saw low-loss optical waveguide development

Submarine cables

The need for disruptive photonic technologies Bandwidth Catastrophe

New optical waveguides Solution: all-optical integration and functionality Basic communication system Propagation control SOURCE MODULATOR DETECTOR Nonlinear functionalities

A Hype Cycle of Nonlinear Optics TIME Trigger Peak of Hype Depths of Despair Hard Work, Realism Low loss waveguides, new materials Nonlinear Solutions to every problem Limited real world use Nonlinearity RESEARCH Practical sources Alternative solutions …

A Hype Cycle of Nonlinear Optics TIME Trigger Peak of Hype Depths of Despair Hard Work, Realism Low loss waveguides, new materials Nonlinear Solutions to every problem Limited real world use Nonlinearity RESEARCH Practical sources Alternative solutions New Trigger

New waveguides enable other possibilities Nonlinear effects now observed using a wider range of sources Match wavelengths of source & waveguide zero dispersion The mid 1990’s saw the development of micro (then nano) structured waveguides with the ability to engineer nonlinearity and dispersion

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 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 1991

Nonlinear pulse propagation Polarization contains linear and nonlinear components In fibres we are concerned with nonlinear polarization from   Neglecting third harmonic generation yields : intensity-dependent refractive index n(I) = n 0 + n 2 I

Modelling the supercontinuum is more complex Linear dispersion SPM, FWM, Raman Self-steepening Three main processes Soliton ejection Raman – shift to long Radiation – shift to short  Physics: NLSE + perturbations We use a generalized nonlinear Schrödinger equation (NLSE)

Modelling agrees with experiment !! Linear dispersion SPM, FWM, Raman Self-steepening Three main processes Soliton ejection Raman – shift to long Radiation – shift to short  Physics: NLSE + perturbations We use a generalized nonlinear Schrödinger equation (NLSE) Experiment Simulation Wavelength (nm) Spectrum (20 dB/div) Output Spectra

Basic description of ultrashort pulses Ultrafast nonlinear fiber optics 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

Who would have predicted this ? Example: planetary discovery Periodic Doppler shift of stellar spectral lines is perturbed by planetary motion Astrocombs measure radial velocity changes of ~ 10 cm/s

Example: broadband light source Molecular fingerprinting S. Diddams et al. Nature 445, 627 (2007) Human breath analysis M. J. Thorpe et al. Opt. Express 16, 2387 (2008)

Supercontinuum applied in Terabit/s telecommunications D. Hillerkuss et al. Here, the nonlinear optics is enabling but the real breakthrough is the system 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

The ability to pressure-tune dispersion in hollow core fibres enables gas-phase nonlinear optics Nonlinear optics in gas-filled fibres enables UV Hollow-core photonic crystal fibres for gas-based nonlinear optics, Nat Photon 8, 278–286 (2014)

Exploiting and managing nonlinearity is critical in the design of a wide range of femtosecond sources in many different application regimes Nonlinear optics is central to fs source development W Sibbett et al. The development and application of femtosecond laser systems Optics Express Focus Issue on Modular Ultrafast Lasers (2012)

Nonlinear saturable absorption is a key component of pulsed lasers Nonlinear optics is central to fs source development

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 are extreme events appearing seemingly from nowhere Ocean Waves Kherif et al. Rogue Waves in the Ocean, Springer (2009) Rogue waves – rare and extreme surface waves Optics Dudley et al. Nature Photonics 8, (2014)

Rogue Waves in a Water Tank Chabchoub et al. Phys. Rev. Lett (2011) Now influencing research in fluid mechanics

Towards truly nanoscale nonlinear optics

Gatass, R. and Mazur, E. Nature Photonics 2,219 (2008) Nonlinear optics of permanent material modification

Tradeoff between interaction length and intensity Gaussian beams cannot penetrate deeply in materials Gaussian beams have an unavoidable tradeoff between interaction length and focal spotsize and power density White,Y. et al, Opt. Express 16,14411 (2008) Femtosecond ablation for machining extended channels is a difficult technology

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 Accelerating Airy Beams M. V. Berry and N. L. Balazs Am. J. Phys (1979) G. A. Siviloglou et al. Phys. Rev. Lett (2007) J. Durnin et al. Phys. Rev. Lett (1987)

New possibilities for micro and nano structuring High aspect ratio channels using Bessel beams Advanced surface machining using accelerating and vortex beams Expt 10  m High aspect ratio nanochannels M. Bhuyan et al. Appl. Phys. Lett (2010) Sending fs pulses in circles F. Courvoiser et al. Opt. Lett. (April 2012) Machining diamond and siliconA. Mathis et al. Appl. Phys. Lett. 101, (2012) Vortex Bessel beams in grapheneB. Wetzel et al. Appl. Phys. Lett. 103, (2013) Graphene

New materials enable progress to nanoscale

Theoretical challenges 1.Input pulse is a high-order soliton 2.Perturbation due to proximity to ZDW 3. Break up into fundamental solitons 4. Soliton dynamics - Raman self-frequency shift (RED) 5. Soliton dynamics - Dispersive wave generation (BLUE) Linear dispersion SPM, FWM, Raman Major Minor

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 (2010) Solitons Parametric amplification Raman scattering Phase conjugation Wavelength conversion

Where are we today with nonlinear nanophotonics? TIME Trigger Peak of Hype Depths of Despair Hard Work, Realism Low loss waveguides, new materials Nonlinear Solutions to every problem Limited real world use Nonlinearity RESEARCH Practical sources Alternative solutions …