Sources supercontinuum visibles à base de fibres optiques microstructurées P. Leproux XLIM - Université de Limoges Journées Thématiques CMDO+, Palaiseau, 24-25 nov. 2008
Palaiseau, 25/11/2008 - P. Leproux - 2/29 Outline Motivations Supercontinuum (SC) generation in Photonic Crystal Fibres SC source based on dual-wavelength pumping SC source based on intermodal FWM Conclusion Biomedical applications of SC sources
Palaiseau, 25/11/2008 - P. Leproux - 3/29 Motivations Demand for broadband optical sources in the biomedical field: High resolution imaging Optial coherence tomography (OCT) Confocal microscopy Nonlinear techniques Cellular diagnosis Flow cytometry One solution combining spatial coherence, compactness and low cost: sub-nanosecond fibre-based supercontinuum sources compact white lasers
Palaiseau, 25/11/2008 - P. Leproux - 4/29 Motivations Coherent anti-stokes Raman scattering (CARS) microscopy CARS microscopy = imaging technique based on the detection of vibrational/rotational modes of molecules excitation of the molecules with a SC source multiplex CARS
Palaiseau, 25/11/2008 - P. Leproux - 5/29 Motivations Flow cytometry characterisation of living cells using an optical excitation information on the cell state provided through diffraction, absorption, fluorescence signals fluorophore response cells excitation cell response lasers λ 1 SC λsource 2 λ 3 sensors
Palaiseau, 25/11/2008 - P. Leproux - 6/29 Outline Motivations Supercontinuum (SC) generation in Photonic Crystal Fibres SC source based on dual-wavelength pumping SC source based on intermodal FWM Conclusion Biomedical applications of SC sources
Palaiseau, 25/11/2008 - P. Leproux - 7/29 SC generation in PCF Output spectrum LASER Input spectrum SC generation = very wide broadening of the incident wave spectrum λ p spectral broadening due to the combination of many 3 rd -order nonlinear effects
Palaiseau, 25/11/2008 - P. Leproux - 8/29 SC generation in PCF (3) Nonlinear effects related to the existence of χ : Optical Kerr effect (nonlinear refractive index) Self-phase modulation (self-kerr effect) Cross-phase modulation (cross-kerr effect) Parametric processes (no field medium energy transfer) Four-wave mixing Third-harmonic generation Inelastic scattering effects (energy transfer) Raman scattering Brillouin scattering
Palaiseau, 25/11/2008 - P. Leproux - 9/29 SC generation in PCF Specific behaviour of PCF? (solid-core air/silica holey fibres) d Λ
Palaiseau, 25/11/2008 - P. Leproux - 10/29 SC generation in PCF Use of small-core (= nonlinear) optical fibres strong confinement of the field over long propagation length Additional advantages of PCF? modification of the conditions of propagation BATH XLIM even more confinement dispersion tailoring high birefringence possible single-mode behaviour over extremely wide spectral range low damage threshold limited launching efficiency Chromatic dispersion (ps/nm/km) Wavelength (nm)
Palaiseau, 25/11/2008 - P. Leproux - 11/29 SC generation in PCF: review (1) First demonstration of visible continuum generation (pumping with 100-fs pulses @ 790 nm) Ranka et al.,, Opt. Lett. 25 (2000) White-light SC generation (pumping with 60-ps pulses @ 647 nm) Coen et al.,, Opt. Lett. 26 (2001)
Palaiseau, 25/11/2008 - P. Leproux - 12/29 SC generation in PCF: review (2) First demonstration of SC generation by using a passively Q-switched microchip laser (pumping with 0.8-ns pulses @ 532 nm) Dudley et al.,, JOSA B 19 (2002) + underlining of the temporal separation between IR solitons in the case of fs regime
Palaiseau, 25/11/2008 - P. Leproux - 13/29 SC generation in PCF: review (3) CW high-power IR continuum generation (15-W pumping @ 1065 nm) Avdokhin, Popov and Taylor, Opt. Lett. 28 (2003) Design of a compact and cost-effective white-light SC source (microchip laser + endlessly single-mode PCF) Wadsworth et al.,, Opt. Exp. 12 (2004) Visible SC generation in a submicron core Leon-Saval Saval, Birks et al.,, Opt. Exp. 12 (2004)
Palaiseau, 25/11/2008 - P. Leproux - 14/29 SC generation in PCF: review (4) Use of cascaded PCF Travers et al.,, Opt. Lett. 30 (2005) Use of long tapers Kudlinski et al.,, Opt. Exp. 14 (2006) Use of a particular device made up of 3 sections Xiong et al.,, Opt. Exp. 14 (2006)
Palaiseau, 25/11/2008 - P. Leproux - 15/29 SC generation in PCF: review (5) Recent results Visibly white light generation in uniform photonic crystal fiber using a microchip laser Stone et al.,, Opt. Exp. 16 (2008) Visible CW SC generation Kudlinski et al.,, Opt. Lett. 33 (2008) Travers et al.,, Opt. Exp. 16 (2008)
Palaiseau, 25/11/2008 - P. Leproux - 16/29 SC generation in PCF Importance of dispersion regime at λ p ZDW (1) Discrete generation of longer wavelengths (1) (2) (3) (2) Homogeneous spectral broadening on both sides of the pump SRS (3) + (1) = dual-wavelength pumping parametric + solitonic
Palaiseau, 25/11/2008 - P. Leproux - 17/29 Outline Motivations Supercontinuum (SC) generation in Photonic Crystal Fibres SC source based on dual-wavelength pumping SC source based on intermodal FWM Conclusion Biomedical applications of SC sources
Palaiseau, 25/11/2008 - P. Leproux - 18/29 SC source based on dual-wavelength pumping Dual-wavelength pumping system? τ = 600 ps, F = 5.4 khz, P peak ~ 10 kw PCF L ~ 4 m Nd:YAG 1064 nm χ (2) 1064 + 532 nm Continuum
Palaiseau, 25/11/2008 - P. Leproux - 19/29 SC source based on dual-wavelength pumping Dual-wavelength pumping system? Characteristics of the PCF: 870 nm (ps/nm/km) 532 nm 1064 nm d ~ 1.5 µm Λ ~ 2.2 µm
Palaiseau, 25/11/2008 - P. Leproux - 20/29 SC source based on dual-wavelength pumping Visible range 532 nm 0 Infrared range 0 1064 + 532 nm -10 Level (db) -10-20 -30 Level (db) -20-30 1000 1200 1400 1600 Wavelength (nm) -40 400 500 600 700 Wavelength (nm) Homogeneous broadening on both sides of the pump @ 532 nm Spatially singlemode Bandwidth ~ 300 nm Smooth supercontinuum No OH - absorption peak Bandwidth: 700 nm at least Champert et al.,, Opt. Exp. 12 (2004) Couderc et al.,, Opt. Exp. 13 (2005)
Palaiseau, 25/11/2008 - P. Leproux - 21/29 SC source based on dual-wavelength pumping Which nonlinear mechanism for visible spectral broadening? XPM from the IR spectrum (solitons) onto the 532-nm pump propagation of green and IR pulses with Vg 532 Vg IR red or blue shift according to the sign of (Vg 532 Vg IR ) Vg IR = Vg 532 XPM red shift v gir > v g532 XPM blue shift v gir < v g532 Genty et al.,, Opt. Lett. 30 (2005) Schreiber et al.,, Opt. Exp. 13 (2005) Räikkönen et al.,, Opt. Exp. 14 (2006) Tombelaine et al.,, IEEE Photon. Technol. Lett. 18 (2006)
Palaiseau, 25/11/2008 - P. Leproux - 22/29 Outline Motivations Supercontinuum (SC) generation in Photonic Crystal Fibres SC source based on dual-wavelength pumping SC source based on intermodal FWM Conclusion Biomedical applications of SC sources
Palaiseau, 25/11/2008 - P. Leproux - 23/29 SC source based on intermodal FWM Use of a highly birefringent PCF Nd:YAG 1064 nm LP 01 LP 11 LP 11 λ C = 500 nm
Palaiseau, 25/11/2008 - P. Leproux - 24/29 SC source based on intermodal FWM Use of a highly birefringent PCF y 500 600 Chromatic dispersion disperion (ps/nm.km) 400 500 300 400 300 200 200 100 100 0 0-100 -100-200 -200-300 -300 LP 1101 x x LP 1101 y y λ ZDW = 825 nm x λ ZDW x = 750 nm λ ZDW = 866 nm y λ ZDW y = 766 nm Pump Pump @ 1064 @ 1064 nm nm -400-500 -600 0,0 0,2 0,2 0,4 0,4 0,6 0,60,8 0,81,0 1,01,2 1,21,4 1,41,6 1,61,8 1,82,0 2,0 Wavelength (µm) (µm) x
Palaiseau, 25/11/2008 - P. Leproux - 25/29 SC source based on intermodal FWM Use of a highly birefringent PCF SC build-up based on wideband intermodal degenerate FWM 0 LP01 1064 nm Lesvigne et al., Visible SC on LP11 mode Level (db) Opt. Lett. Lett. 32 (2007) LP11-1 0 1482 nm -2 0 830 nm -3 0 LP01-4 0 LP11-5 0 200 400 600 800 1000 1200 W a v e le n g th (n m ) 1400 1600
Palaiseau, 25/11/2008 - P. Leproux - 26/29 Conclusion PCF = attractive media for handling the nonlinearity by controlling the dispersion SC generation in PCF design of spatially coherent white-light sources (UV IR) Use of sub-ns microchip lasers design of very compact white lasers SC sources = helpful for many biomedical applications but still a huge effort to be devoted for their adaptation
PRODUITS 370 2400 nm
Palaiseau, 25/11/2008 - P. Leproux - 28/29 Exemples d applications démontrées Spectro-tomographie (OCT spectroscopique) (signal OCT obtenu sur une solution test d éosine) Microscopie CARS (image de cellules de tabac Nicotiana tabacum, type BY2) L. Froehly et al., M. Okuno et al., Inter. Journal of Biomed. Imaging, Article ID 752340, 2008 Optics Letters 33, 923-925, 2008 (collab. Univ. de Besançon, France) (collab. Univ. de Tokyo, Japon)
Palaiseau, 25/11/2008 - P. Leproux - 29/29 Questions?