11th Advanced Accelerator Concepts Workshop Stony Brook New York, June 22nd, 2004

Solid-State 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

UCF College of Optics & Photonics/CREOL-FPCE

May 17, 1960: The Beginning. Ted Maiman’s . Nature 187, 493 (August 6, 1960).

• Nd:glass optical : Snitzer, PRL 7, 444(1961). • Q-Switched Laser: Hellwarth, Bull. Am. Phys. Soc. 6, 414 (1961). • GaAs : 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 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/ 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. UCF College of Optics & Photonics/CREOL-FPCE Ti:Sapphire UCF College of Optics & Photonics/CREOL-FPCE

• Sapphire great optical quality, high damage threshold – Also superior thermal material. Sapphire is often used as transparent heat sink • Ideal saturation fluence 2 –Fsat = 1 J/cm yields a stretching requirement of only 200 ps – Just below damage threshold • Huge bandwidth – Theoretically could support 3-fs pulses • Short lifetime – 3 us requires laser pumping or heroic flashlamp circuitry • SHG-Nd pumping. No high-power green laser diodes. • Widely implemented for 1-100 TW class systems. • PW’s: JAERI, FOCUS Cr4+:YAG

UCF College of Optics & Photonics/CREOL-FPCE

• Versatile Pumping – Diode-pumped @ 940-nm, 980-nm – Laser-pumped by Nd, Yb lasers • Operates at telecomm wavelengths (1.3 and 1.5um) • Excellent optical quality material available (Passive Q- Switch Use) • Ideal saturation fluence – Fsat ~ 0.5 J/cm2 yields a stretching requirement of only 100 ps – Just below damage threshold • Large bandwidth – Theoretically could support sub-10 fs pulses • Short lifetime – 4.5 us requires laser pumping – High rep-rate pulsed amplifier for 10-100 kHz applications Er:fiber UCF College of Optics & Photonics/CREOL-FPCE

• Telecom wavelengths: much hardware available – EDFA: The most common telecommunication fiber amplifier • All diode pumped • Short pulses – 100 fs possible • Large scale hosts not available so limited energy out • Reliable source of sub-100-fs pulses at 1550nm. • Sub-MW peak powers: TW/cm2 at 10’s MHz rep-rates OPCPA?

UCF College of Optics & Photonics/CREOL-FPCE

(T. Ditmire) Cr:LiSAF UCF College of Optics & Photonics/CREOL-FPCE

• Flashlamp pumpable and diode pumpable – 67 µs lifetime, absorption at diode wavelengths – Diode pumped fs oscillators have been made with this material • Good but not best bandwidth – Theoretically around 10 fs • Inferior material properties – Early crystals dissolved in their water cooled housings – Easily fractured • Inferior optical quality Pros & Cons of Amp Shape

UCF College of Optics & Photonics/CREOL-FPCE

Rod Zigzag Slab Fiber Disk

Thermal Lensing Significant, but can be None in y-z (zigzag Significant, but can be Minimal due to 1D heat dealt with. averaging), weak in x-z. dealt with. flow.

Stress Significant, but can be None in ideal case. None for glass fibers. Minimal due to 1D heat dealt with. flow. Birefringence

Mode Control Good at low power. Challenging, especially at Good for single mode. Good large aspect ratios. More challenging for large mode fibers.

Mode Fill Factor Up to ~80% Up to ~80% ~100% Up to 95% (TEM00)

Best Power with 500 W, M2 ~ 1.5 3 kW, M2 ~ 2.5 1.3 kW, M2 ~1.3 13 kW, M2 ~ 4 good Beam Qual

Key Challenge Thermal Lensing & Mode Mode, Mode, and Mode Aperture limit & beam Thermal Distortions combining. USP nonlinearities. ASE. What Does the Future Hold?

UCF College of Optics & Photonics/CREOL-FPCE

• Diode-pumped Fiber Osc’s & Amps: – Yb (1um), Er (1.5um) – High rep-rates, limited by USP NLO • Disk Amps: Yb, Cr4+ • X-CPA & SOA’s • Nano-photonics & Integrated Optics • Dispersion Management – Improved Gratings (~J/cm2 Damage Thresh.) – Chirped Fiber Bragg Gratings – Compact Free-Space Systems • Engineered Composite Media – Large-area “crystals”: ceramic, fused, etc. – Thermal Management Improvements (because we must!) • Multi-kW, Multi-kHz USPs soon! • GHz GW and MHz TW? X-CPA Generic Architecture

Pre Optical Primary Optical Modelocked Amplification Amplification Laser

Final Compression

Pre-Stretch ~100 psec

Primary Stretch – 20 nsec Primary Compress DARPA Challenge UCF College of Optics & Photonics/CREOL-FPCE Stu’s Shoe UCF College of Optics & Photonics/CREOL-FPCE DARPA Challenge UCF College of Optics & Photonics/CREOL-FPCE Size Reduction Obtainable from XCPA

UCF College of Optics & Photonics/CREOL-FPCE

1 inch 0.5 inch

A packaged mode locked laser diode X-CPA USPL

46 inches

This is the laser diode based Mode locked laser to the same scale as the traditional mode 10inches Locked laser for a Ti Sapphire Traditional mode locked laser for Ti:Sapphire USPL (KM Labs, Boulder). 2760 in3 for the volume for the traditional Ti Sapphire ML source 0.125 in3 for the ML source for the X-CPA 22080 time reduction in volume X-CPA Impact UCF College of Optics & Photonics/CREOL-FPCE

9in = 48in 10in 24in 14in 8in

Volume 10368in3 for a 1 Watt Ave Power Ti:Sapphire Power Supply and Water cooling Volume 1120in3 for a 0.5 Watt Ave Power system are not shown in the photograph XCPA Power Supply not shown.

3 Volume of power supply 3456in3 Volume of power supply ~560in Volume of water cool 3000in3 Water Cool Not Required