11th Advanced Accelerator Concepts Workshop Stony Brook New York, June 22nd, 2004 Solid-State Laser Technology Prof. Craig W. Siders [email protected] College of Optics & Photonics / CREOL-FPCE The University of Central Florida Orlando FL University of Central Florida College of Optics & Photonics • CREOL • FPCE College of Optics & Photonics / CREOL-FPCE UCF College of Optics & Photonics/CREOL-FPCE College of Optics & Photonics / CREOL-FPCE UCF College of Optics & Photonics/CREOL-FPCE Historical Introduction UCF College of Optics & Photonics/CREOL-FPCE History: The Golden Age of Lasers UCF College of Optics & Photonics/CREOL-FPCE May 17, 1960: The Beginning. Ted Maiman’s Ruby Laser. Nature 187, 493 (August 6, 1960). • Nd:glass optical fiber laser: Snitzer, PRL 7, 444(1961). • Q-Switched Laser: Hellwarth, Bull. Am. Phys. Soc. 6, 414 (1961). • GaAs laser diode: GE, IBM, Lincoln Labs,1962. • Modelocking, 1963. • Nd:YAG laser, 1964. Early SSL Applications UCF College of Optics & Photonics/CREOL-FPCE Compliments A. Siegman New materials, techniques provide unprecedented laser intensities ... BBiigg SScc iieen nccee inin thethe bb LLaa aallll SSmm Focused Optical Focused 1020 Relativistic Intensity nonlinear optics LWFA Field (V/m) 2 + (W/cm ) Non perturbative 1012 non linear optics 1015 1010 mode-locking Chirped Pulse 10 Q-switching 10 Amplification (CPA) 1960 1970 1980 1990 2000 Perry & Mourou, Science 264, 917 (1994). year CWS Finishes PhD CWS Starts PhD w/ MCD Chirped Pulse Amplified Laser System UCF College of Optics & Photonics/CREOL-FPCE UCSDUCSD 2020--Hz,Hz, 2020--fsfs 55--TWTW LaserLaser SystemSystem •• CompactCompact •• UltrafastUltrafast –– 2020 fsfs •• Ti:SapphireTi:Sapphire •• SynchronousSynchronous PumpPump && ProbProbee •• 100100 mJmJ @@ 2020 HzHz Chirped Pulse Amplification UCF College of Optics & Photonics/CREOL-FPCE Strickland & Mourou, Opt. Comm. 56, 219 (1985). Short pulse oscillator Cook, Proc. IRE, 310 (1960). ∆t = F /I t stretch sat damage Nd:Glass ~ 1 ns Dispersive delay line Ti:Al2O3 ~ 200 ps t Solid state amplifiers t ! Saturation is Reached Safely: Ipeak << Idamage Inverse delay line ∆t ! Peak Power Increase Proportional to stretch >>1000 ∆t0 t Disperse-O-Matic Freeware (WARNING: Shameless Self-Promotion) UCF College of Optics & Photonics/CREOL-FPCE http://dom.creol.ucf.edu/ http://www.creol.ucf.edu/reu/ Chirped Pulse Amplified Laser System UCF College of Optics & Photonics/CREOL-FPCE UCSDUCSD 2020--Hz,Hz, 2020--fsfs 55--TWTW LaserLaser SystemSystem •• Ti:SapphireTi:Sapphire •• 800800--nmnm •• 100100--mJmJ // pulsepulse •• ExcellentExcellent focusingfocusing •• 101018 W/cmW/cm2 Ultrafast CPA Characteristics UCF College of Optics & Photonics/CREOL-FPCE Compactness and high repetition rate Nova Ultrafast CPA System Pulse duration 1 ns Pulse duration 20 fs 10 kJ/beam 100 mJ/beam 10 TW/beam 5 TW/pulse 1 shot/hour 72,000 shots/hour Ultrafast CPA systems allow high experimental “Utility” • Signal averaging even at extreme intensities • High average flux of laser-generated x-rays, particles Big Science in the Small Laboratory UCF College of Optics & Photonics/CREOL-FPCE High-field High-rep-rate Ultrafast lasers High-flux ~10-keV x-rays Even Bigger Science in the Big Lab UCF College of Optics & Photonics/CREOL-FPCE JAERI Petawatt SAUUL Report: >10TW Facilities UCF College of Optics & Photonics/CREOL-FPCE SAUUL Report: PW Facilities UCF College of Optics & Photonics/CREOL-FPCE UT Austin 1PW Nd:glass 160fs 130J Under Construction What We Care About UCF College of Optics & Photonics/CREOL-FPCE v aI=≈osc 1 or ≈1018 W/cm2 0 c Laser Sources WG, AACW ‘96 Pulse Duration UCF College of Optics & Photonics/CREOL-FPCE Agostini & DiMauro, Rep. Prog. Phys. 67 813 (2004). Average Power Challenge UCF College of Optics & Photonics/CREOL-FPCE • Traditional USP lasers are limited to watt-level average powers. • Transitioning of short pulse high-intensity kW applications require W kW-level USP lasers. mW Efficiency & Saturation Perspective UCF College of Optics & Photonics/CREOL-FPCE Saturation Fluence UCF College of Optics & Photonics/CREOL-FPCE σ hν F = sat σ hν Efficient Solid-State Amplifier UCF College of Optics & Photonics/CREOL-FPCE • High Efficiency in Final Amplifier – Operate above the saturation fluence Fsat Compactness & Saturation Fluence UCF College of Optics & Photonics/CREOL-FPCE 1-J Beam Areas at Fsat RG6 & Semiconductors 2 Ti:Sapphire Fsat ~ 1 mJ/cm 2 Fsat ~ 1 J/cm Yb:YAG Yb:Glass Nd:YVO4 2 Fsat ~ 30-50 J/cm Nd:YAG Nd:YLF Nd:Glass Cr:YAG 2 Fsat ~ 5 J/cm Cr:Forsterite Cr:LiSAF Er:YAG Cr:LiCAF Er:Glass High Fsat materials can be more compact. Saturation Intensity UCF College of Optics & Photonics/CREOL-FPCE CW-Pumped Pulse Amplifier 30 30 Gain recovery time τ 25 25 20 B 20 B d d n 15 n 15 i i a a F hν G G sat 10 10 I sat == 5 5 τ στ 0 2 4 6 8 10 5.9 5.95 6 6.05 6.1 t @ns D t @ns D 1000 1000 2 2 m m c c 800 800 W W M M 600 600 t t u u o o _ _ I 400 I 400 n n i 200 i 200 _ _ I, I, 0 0 0 2 4 6 8 10 5.9 5.95 6 6.05 6. t @ns D t @ns D Energy Considerations in USPs UCF College of Optics & Photonics/CREOL-FPCE Laser Media UCF College of Optics & Photonics/CREOL-FPCE Damage Fluence Limits UCF College of Optics & Photonics/CREOL-FPCE Ultrashort-pulse damage thresholds Dielectrics limit usable fluences. Metals B. Stuart, et al., JOSA B 13, 459 (1996); ibid, PRL 74 (1995). Pronko, Opt. Comm. 114, 106 (1995). Laser Media UCF College of Optics & Photonics/CREOL-FPCE Optical Damage Limits UCF College of Optics & Photonics/CREOL-FPCE eXtreme Chirped Pulse Amplification UCF College of Optics & Photonics/CREOL-FPCE XCPA Semiconductor Amplifier Limits ASE & Nonlinearities Single-pulse CPA stretched compressed Solid-State Amp Burst mode SOA gain XCPA sub-µs to ms compressed SOA operated as CW amplifier. 50-MHz pulse train stretched to ~ 20ns y 00 n t i 100 i 50 _ s I n e - t 20 n t I u 10 10 eXtreme CPA o UCF College of Optics & Photonics/CREOL-FPCE _ I 10000 10 100 1000 10000 2 D Pulse Durations: 2-ps (red), 20-psG0 (yellow)I_in, 200-ps@MW (green),cm D 2-ns (blue), 20-ns (violet) 10000 2 2 10000 m m c 1000 c J 1000 J m m 100 100 n n i i _ 10 _ 10 F F - 1 - 1 t t u u o 0.1 o 0.1 _ _ F F 500 1000 10 100 1000 10000 10 G0 I_in @MW cm 2D 200-ps gain lifetime, 30-dB gain 2 2 Fsat = 1.0-mJ/cm ; Isat = 5.1 MW/cm λ = 980-nm; σ = 2.5x10-16 cm2 Optical Damage Limits UCF College of Optics & Photonics/CREOL-FPCE Thermal Damage Limits UCF College of Optics & Photonics/CREOL-FPCE Sub-0.5ps Materials UCF College of Optics & Photonics/CREOL-FPCE High-power laser diodes UCF College of Optics & Photonics/CREOL-FPCE LightStack from Coherent 2-kW @ 940-nm. 50% wallplug efficiency 2 19-bar arrays in series electrically, parallel cooling Pump Stack Originally developed for Ytterbium Fiber Pump High-power laser diodes UCF College of Optics & Photonics/CREOL-FPCE Sub-0.5ps Materials UCF College of Optics & Photonics/CREOL-FPCE High-Power Diode Pump-able UCF College of Optics & Photonics/CREOL-FPCE What We Care About UCF College of Optics & Photonics/CREOL-FPCE v aI=≈osc 1 or ≈1018 W/cm2 0 c Laser Sources WG, AACW ‘96 Systems Which Access AAC-Relevant Rep-Rates UCF College of Optics & Photonics/CREOL-FPCE 103 102 Co:MgF2 Yb:Glass ] Alexandrite 2 Er:Glass 1 m 10 Yb:YAG c Yb:KGW Nd:Glass 0 10 Nd:YLF CTir4:S+a:Fpphorsitrerie te Nd:KGW Cr4+:YAG Nd:YAG Cr4+:CUNYite 10-1 Nd:Vanadate on Fluence [J/ i -2 10 AAC Saturat 10-3 10-4 10-1 100 101 102 103 Saturated Rep-Rate [kHz] Energy Storage Density UCF College of Optics & Photonics/CREOL-FPCE 103 102 Co:MgF2 Yb:Glass ] Alexandrite 2 Er:Glass 1 m 10 Yb:YAG Yb:KGW /c Nd:Glass J e [ 0 Cr4+:Forsterite 10 Ti:SapphireNd:YLF Cr4+Nd:YAG:KGW Nd:YAG Cr4+:CUNYite 10-1 Nd:Vanadate tion Fluenc a 10-2 Satur R6G Semi 10-3 10-4 10-1 100 101 102 103 104 Energy Storage Density [J/cm3] Nd:Glass UCF College of Optics & Photonics/CREOL-FPCE • Energy storage good 2 –Fsat = 7 J/cm • Pumping straightforward – 400 microsecond lifetime easily flashlamp pumpable • Dispersion control easier – Picosecond pulses require only GDD and maybe cubic compensation • Repetition limited – Thermal loading a problem. Must wait to re-equilibrate • Pulse duration limited to around a picosecond – Typically 300 fs to 1 ps • First PW Laser – LLNL/NOVA PW • Majority of planned PW’s are Nd:Glass Yb:Glass UCF College of Optics & Photonics/CREOL-FPCE • High energy storage 2 –Fsat = 30-50 J/cm – Damage is a major issue in efficiency and robustness • Diode pumpable – Very long lifetime (840 µs) and absorption at diode wavelengths (915nm, 980nm). Not optimal for 10-100kHz rep-rate applications. • Shorter pulses possible – Fluoresence bandwidth should support ~100 fs • Stretching requirements difficult - CFBG? – ∆t = 6ns to reach one times saturation safely • Can be easily implemented in Fiber geometry – >kW CW average powers, 65% slope efficiency demonstrated (Limpert CLEO ‘04) – 0.6-mJ, 1.6-kHz, 800-ps stretched, 400-fs compressed (Limpert CLEO ‘04) • Yb:glass PW’s under construction • Yb:SFAP - Mercury Laser @ LLNL. 100J, 10 Hz, ns.