SOLITON PATTERNS FORMATION IN FIBER LASERS F. Sanchez 1 , M. Salhi 1 - PowerPoint PPT Presentation

SOLITON PATTERNS FORMATION IN FIBER LASERS F. Sanchez 1 , M. Salhi 1 , A. Komarov 1,2 , F. Amrani 1 , A. Niang 1 1 Laboratoire de Photonique d’Angers EA 4464, Université d’Angers, 2 Bd Lavoisier, 49000 Angers, France 2 Institute of Automation and Electrometry, Russian Academy of Sciences, Acad Koptyug Pr. 1, 630090 Novosibirsk, Russia francois.sanchez@univ-angers.fr 4-8 June 2012 Solitons, Collapses & Turbulence 1 Novosibirsk - RUSSIA

Outline of the presentation 1. Introduction 2. Nonlinear polarization rotation fiber laser 3. Figure-of-eight laser 4. 10 W NLPR fiber laser 5. Conclusion 4-8 June 2012 Solitons, Collapses & Turbulence 2 Novosibirsk - RUSSIA

1. Introduction Fiber laser operating in the anomalous dispersion regime β Tot < 0 Negative GVD Soliton regime (energy quantization) 2 Multiple pulsing � 100 - 1000 pulses / cavity round-trip High pumping power T=1/FSR Soliton interactions � Soliton pattern formation � Self-organized (or disorganized) structures analogous to the states of the matter � gas, liquid or solid 4-8 June 2012 Solitons, Collapses & Turbulence 3 Novosibirsk - RUSSIA

2. NLPR fiber laser Experimental setup Mode-locking through nonlinear polarization rotation PC VSP VSP β Tot = − 2 < L 0 . 04 ps 0 2 Er/Yb DCF ( β 2 < 0) Soliton regime Pump @ 980 nm Double-clad structure SMF 28 Er:Yb amplifier ( β 2 < 0) Polymer Doped Core Isolator Rejection port 10/90 1 st Clad Coupler λ /2 λ /4 λ /4 Pump Signal Output DSF (10%) ( β 2 > 0) Control of PBS � T= 105 ns dispersion � P p = 3.3 W Control of nonlinear losses 4-8 June 2012 Solitons, Collapses & Turbulence 4 Novosibirsk - RUSSIA

2. NLPR fiber laser Soliton Gas Time distribution Optical spectrum • � 380 solitons • No spectral modulation � • Fill all the available space along no mutual coherence between pulses the cavity � gas • Delays ��� strongly vary 4-8 June 2012 Solitons, Collapses & Turbulence 5 Novosibirsk - RUSSIA

2. NLPR fiber laser Soliton Gas Autocorrelation trace Histogram of the delays • No regular distribution ∆ τ = 236 ps Mean value • Large pedestal � solitons are σ τ = 207 ps in perpetual relative movement Standard deviation ∆ Analogous to a gas of solitons 4-8 June 2012 Solitons, Collapses & Turbulence 6 Novosibirsk - RUSSIA

2. NLPR fiber laser Soliton Liquid Time distribution Optical spectrum • � 400 solitons • Small spectral modulation � • Fill only a small part of the small mutual coherence between pulses the cavity � liquid or solid • Solitons move � liquid 4-8 June 2012 Solitons, Collapses & Turbulence 7 Novosibirsk - RUSSIA

2. NLPR fiber laser Soliton Liquid Autocorrelation trace • Small pedestal � solitons are in perpetual relative movement • Difficult to characterize due to the small separation between pulses and to their perpetual movement (bound states can be created and destroyed) Analogous to a liquid of solitons (or clusters of solitons) 4-8 June 2012 Solitons, Collapses & Turbulence 8 Novosibirsk - RUSSIA

2. NLPR fiber laser Soliton Polycrystal Time distribution Optical spectrum • � 520 solitons • Moderate spectral modulation � • Fill only a small part of the mutual coherence between pulses the cavity � liquid or solid • Solitons at rest � solid • No order at large scale � glass 4-8 June 2012 Solitons, Collapses & Turbulence 9 Novosibirsk - RUSSIA

2. NLPR fiber laser Soliton Polycrystal Autocorrelation trace Triangular envelop � bound-state of 23ps 8 solitons • No pedestal � solitons are at rest Incoherent mixture of bound-state of • Order at small scale � microcrystal variable number of solitons Analogous to a polycrystal of solitons 4-8 June 2012 Solitons, Collapses & Turbulence 10 Novosibirsk - RUSSIA

2. NLPR fiber laser Soliton Polycrystal How many bound-state in the pattern ? How many solitons in the different bound-states ? Regular spectral modulation � constant pulse separation in all bound-states, 23 ps Bound-states For a given bound-state k, the number of pulses is obtained from ∆ T ( ps ) = k N k 23 ps This is repeated for every ‘packet’ of solitons visible in the temporal trace ∆ T k 4-8 June 2012 Solitons, Collapses & Turbulence 11 Novosibirsk - RUSSIA

2. NLPR fiber laser Soliton Polycrystal Histogram of the number the bound-states containing a given number of solitons 4-8 June 2012 Solitons, Collapses & Turbulence 12 Novosibirsk - RUSSIA

2. NLPR fiber laser Soliton Crystal Time distribution Optical spectrum • Strong spectral modulation � • � 480 solitons mutual coherence between pulses • Fill only a small part of the • Regular modulation � pulses the cavity � liquid or solid • Solitons at rest � solid are equidistant 4-8 June 2012 Solitons, Collapses & Turbulence 13 Novosibirsk - RUSSIA

2. NLPR fiber laser Soliton Crystal Autocorrelation trace • Equidistant and identical pulses � Bound-state of hundreds of solitons 11 ns = ≈ N 480 pulses 23 ps Analogous to a crystal of solitons 4-8 June 2012 Solitons, Collapses & Turbulence 14 Novosibirsk - RUSSIA

3. Figure-of-eight fiber laser Experimental setup Mode-locking through a nonlinear β Tot = − 2 < L 0 . 04 ps 0 2 amplifying loop mirror Soliton regime DSF SMF 28 ISO � T= 136 ns PC � P p = 3.2 W Er/Yb DCF 50/50 Coupler Output 20 % PC Pump @ Pump @ 980nm (4W) 980nm (4W) Unidirectionnal ring (UR) Nonlinear Amplifying Loop Mirror (NLAM) 4-8 June 2012 Solitons, Collapses & Turbulence 15 Novosibirsk - RUSSIA

3. Figure-of-eight fiber laser Soliton Gas Time distribution Autocorrelation trace • Large pedestal � perpetual movement • Fill all the available space along • No spectral modulation � the cavity and perpetual movement � gas no mutual coherence between pulses Analogous to a soliton gas 4-8 June 2012 Solitons, Collapses & Turbulence 16 Novosibirsk - RUSSIA

3. Figure-of-eight fiber laser Soliton Liquid Time distribution Autocorrelation trace • The solitons fill only a small part of the cavity and are in relative motion. • The autocorrelation trace exhibits some sharp and nearly equidistant peaks revealing that there exist some clusters of solitons. • The optical spectrum points out a small modulation which suggests that a small coherence starts to occur between pulses Analogous to a liquid of solitons (or clusters of solitons) 4-8 June 2012 Solitons, Collapses & Turbulence 17 Novosibirsk - RUSSIA

3. Figure-of-eight fiber laser Soliton Polycrystal Autocorrelation trace Time distribution 1.0 Nearly triangular envelop 0.8 Intensity (a.u.) 0.6 0.4 0.2 0.0 -100 -75 -50 -25 0 25 50 75 100 Delay (ps) Optical � Autocorrelation trace: equidistant peaks with a nearly spectrum triangular envelope � soliton crystals. � Optical spectrum: strong modulation � constant phase relation between pulses inside a crystal (strong mutual coherence). Incoherent mixture of nearly identical bound-state Analogous to a polycrystal of solitons 4-8 June 2012 Solitons, Collapses & Turbulence 18 Novosibirsk - RUSSIA

3. Figure-of-eight fiber laser Soliton Crystal Autocorrelation trace Time distribution 14.5 ps 7 ns Optical spectrum • Regular train of identical and equidistant pulses • Strong spectral modulation � strong mutual coherence between pulses � Bound-state of hundreds of solitons 7 ns = ≈ N 480 pulses 14 . 5 ps 4-8 June 2012 Solitons, Collapses & Turbulence 19 Novosibirsk - RUSSIA

3. Figure-of-eight fiber laser Diphasic Mixture Autocorrelation trace Time distribution Optical spectrum • Peaks: solitons are at rest • Plateaus: solitons move • Autocorrelation trace: regular distribution inside the peaks • Optical spectrum: small mutual coherence Alternate series of solid and liquid states 4-8 June 2012 Solitons, Collapses & Turbulence 20 Novosibirsk - RUSSIA

3. Figure-of-eight fiber laser Diphasic Mixture Reconstruction The total electric field consists in an incoherent superposition of alternate solid and liquid states   N n ∑  ∑  = − ∆ E ( t ) E t T   n j   =  =  n 1 j 1 Odd n’s: cristal. Even n’s: liquid 4-8 June 2012 Solitons, Collapses & Turbulence 21 Novosibirsk - RUSSIA

4. 10 W NLPR fiber laser Experimental setup All-fiber laser β Tot = − 2 < L 0 . 12 ps 0 2 � T= 152.9 ns DSF � P p = 15 - 25 W 10 W Er:Yb DCF 10 W Er:Yb DCF Amplifier Amplifier Isolator Control Coupler 50/50% Output 10% Starter Starter Polarizing PC PC Isolator 4-8 June 2012 Solitons, Collapses & Turbulence 22 Novosibirsk - RUSSIA

4. 10 W NLPR fiber laser P p = 15 W 9.3 ns 10 ps Soliton crystal 9 .3 ns = ≈ N 930 pulses 10 ps 4-8 June 2012 Solitons, Collapses & Turbulence 23 Novosibirsk - RUSSIA