The Proposed MIT X-ray Laser Facility: Laser Seeding to Achieve the Transform Limit

Transcription

1 MIT X-ray Laser Project The Proposed MIT X-ray Laser Facility: Laser Seeding to Achieve the Transform Limit 30 or more independent beamlines Fully coherent milli-joule pulses at khz rates Wavelength range from 200 nm to 0.1 nm Envisioned as the next step after LCLS David E. Moncton Massachusetts Institute of Technology TESLA Collaboration Meeting January 21, 2004

2 MIT X-ray Laser Project To realize such a source, the most sophisticated laser and accelerator technology must be integrated together. The laser generates the coherent signal MIT Ultrafast Laser Group Franz Kaertner, Erich Ippen, et al An accelerated electron beam amplifies and frequency shifts the laser radiation MIT Bates Laboratory William S. Graves et al

3 MIT X-ray Laser Project Main oscillator Fiber link synchronization Seed laser UV Hall Pump laser Seed laser X-ray Hall Pump laser Undulators 200 nm 30 nm Undulators 1 nm Injector laser 10 nm 0.3 nm 1 GeV 2 GeV SC Linac 4 GeV 0.3 nm SC Linac 0.1 nm 10 nm 3 nm Upgrade: 0.1 nm at 8 GeV 1 nm Undulators Seed laser Nanometer Hall Pump laser

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5 Advances in Timing Distribution and RF-Synchronization Franz X. Kaertner Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology Cambridge, USA

6 Outline I. Challenges of MIT X-Ray Laser Project II. Compact and reliable Few-(Single)-Cycle Laser Sources III. Optical clocks and large scale timing distribution (10 fs) IV. RF-regeneration and synchronization V. Conclusion

7 Challenges of MIT X-Ray Laser Project Optical clock Optical master oscillator Mode-locked laser Frequency standard Timing distribution Timing stabilized fiber links High average power Few- Cycle Lasers Photo-Inj. t = 10 fs HHG-Seed t = 10 fs Opt. Probe t = 10 fs RF-Synch. Pulsed Klystron Gun RF-components, XGHz t = 10 fs Linac Undulator

8 5fs, Octave Spanning, Prismless Ti:sapphire Laser Compact and Reliable Source BaF2 Ti:Al 2 O 3 crystal PUMP OC BaF2 - wedges Base Length = 30cm for 82 MHz Laser L = 20 cm Spectrum [db] Wavelength [nm] Spectrum [a.u.] MHz 80 MHz Ultra-Broadband Double-Chirped-Mirror Pairs Reflectivity Pump Design Wavelength, nm Measured Pair Group Delay (fs) Few-Cycle Cr:Forsterite, Cr:YAG, Cr:LICAF Active synchronization of Ti:Sapphire Cr:Forsterite by balanced optical cross-correlation 0.3 fs measured from.2mhz - 2MHz Long term stable and drift free T. Schibli et al, Opt. Lett. 28, pp. 947, 2003.

9 Cr:fo Balanced Cross-Correlator Output ( nm) Δt Ti:sa (1/496nm = 1/833nm+1/1225nm). Rep.-Rate Control 0V SFG SFG 3mm Fused Silica

10 Measuring the residual timing jitter Output ( nm) SFG Jitter Analysis Cr:fo -GD/2 Ti:sa (1/496nm = 1/833nm+1/1225nm). Rep.-Rate Control SFG SFG 3mm Fused GD Silica

11 Experimental result: Residual timing-jitter Cross-Correlation Amplitude Time [fs] Timing jitter 0.30 fs (2.3MHz BW) 40 Time [s] The residual out-of-loop timing-jitter measured from 10mHz to 2.3 MHz is 0.3 fs (a tenth of an optical cycle) 60 Long Term Drift Free

12 Timing Stabilized Fiber Links (<1km) PZT Dichroic Beam Splitter 532 nm Pump laser Fiber Link Fixed Length L 10 fs Ti:sapphire laser Cross Correlator All Fiber Implementations at 1.5 µm with high repetition rates Two wavelength filter Assuming no fiber length fluctuations faster than 2L/c.

13 Sub-10 fs RF-Synchronization (with Mike Perrott, MIT Micro-Technology Laboratory ) Repetition Rate: f R RF: f = m f R Recovered from optical pulse train VCO Loop Filter

14 Self-balanced sub-10 fs RF- Synchronization λ opt /4 (2n+1) λ RF /2

15 Conclusions Laser seeding needs large scale 10-fs timing distribution Can be accomplished by length stabilized fiber links Scheme for phase stable RF-regeneration has been outlined Synchronization between independent lasers with less than 0.3 fs jitter has has been demonstrated HHG-provides enough seed energy to overcome SASE Highly reliable short pulse high power laser system based on Parametric Chirped-Pulse Amplification for HHG

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17 High-Harmonic Seed Generation by Parametric Chirped Pulse Amplification Today: HHG from 100 nm 30 nm, η = , nm needs 800 nm (pioneered by M. Murnane, H. Kapteyn, F. Krausz, ) Cryogenically cooled Ti:sapphire Lasers 800 nm with 1kHz rep.-rate Large Average Power (1kW) Fiber Lasers With High Beam Quality + Coherent Addition in Cavities, mj, at 1kHz, 1ns pulses 2 nd -Harmonic 1ns, 50mJ, 532 nm Carrier-Envelope Stabilized Ti:Sapphire, 4 fs, 100MHz GV-matched P-CPA with BBO Stretcher Compressor Phase Controlled 5fs, 5mJ, 1 khz Phase Control

18 Compact and low cost ultrashort pulse laser sources for biomedical imaging J. G. Fujimoto and F. X. Kaertner, ECS Advanced Technologies for Optical Clocks E. P. Ippen, D. Kleppner, MURI-ONR Lock to 1S-2S Lock 486 nm x2 972 nm Diode x2 Excite 2S-nS Cold hydrogen Standard versus ultrahigh resolution OCT image of human retina using a femtosecond laser. 100 µm Dye laser In-vivo ultrahigh resolution OCT image of African frog tadpole. Octave Spectra Direct Self-Referencing Semiconductor Devices for Control of Solid-State Laser Dynamics F. X. Kaertner, E. P. Ippen and L. Kolodziejski MIT, ECS Will enable high-repetition rate, low-jitter lasers at 1.5 µm W. Drexler, et al Nature Med., 7, (2001).

19 Experimental Results on Transmission of Optical Frequency Standards By active fiber induced phase noise cancelation

20 Balanced Cross-Correlator Output ( nm) Δt Δt Cr:fo -GD/2 Ti:sa (1/496nm = 1/833nm+1/1225nm). Rep.-Rate Control 0V SFG SFG 3mm Fused GD Silica

21 Balanced Cross-Correlator

22 Cooperation on Frequency Metrology and Timing Distribution Both at MIT and JILA-NIST: MURI-Projects funded by ONR Frequency Metrology and Femtosecond Technology for Optical Clocks MIT: E. P. Ippen (PI) Y. Fink F. Kaertner D. Kleppner L. Kolodziejski J. Shapiro F. Wong JILA-NIST: J. Ye (PI) S. Diddams L. Holberg.. J. Ye, JOSA B 20, (2003)

23 Spectra from 80 MHz and 150 MHz Laser 0 Spectrum [db] Spectrum [a.u.] Wavelength [nm] MHz 80 MHz

24 Broadband, Prismless Ti:sapphire Laser PUMP AOM PZT OC Loop filter Phase Detector 1:32 LO PMT Polarizer 580 nm Filter BBO DM DM 1160 nm Time delay 580 nm 1f-2f Self-referenceing: Reichert, et al. Opt. Comm. 172, 59 (1999) Telle, et al. Appl. Phys. B 69, 327 (1999) S. Diddams, et al. Science, 288, 635 (2000)

25 Pump- and Carrier-Envelope Phase Noise system noise floor pump noise fceo phase error PSD (rad^2/hz) PSD (a.u.) Frequency (Hz) φ 2 CE = 1.4 rad 20mHz 1MHz -60

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27 Directly Diode-pumped Photo-Injector To achieve a homogeneous e-beam bunch Temporal: Flat-top shaped Yb:Fiber Laser, 50fs 1 ps rep. Rate 100 MHz Pulse Selector Acusto-Optic Programable Pulse Shaper (Dazzler, Fastlight) Yb:fiber amplifier IPG-Photonics 20ps, 10µJ, nm 4 th -Harmonic 20ps, 1µJ, 1-10 nm All-Fiber, as much as possible No misalignment!

28 Long Pulse Seed Generation 2ps, (266) nm Yb:Fiber, 2ps rep. Rate 100 MHz Pulse Selector Acusto-Optic Programable Pulse Shaper (Dazzler, Fastlight) Yb:Fiber/ Yb:YAG-regen. 2ps, 200µJ, 1-10 nm 4 th -Harmonic 2ps, 20µJ, (266) nm

29 Sub-fs High-Harmonic Generation M. Hentschel, et al., Nature, 414, 509 (2001) A. Baltuska, et al., Nature, 421, 612 (2003) Electric Field Φ = 0 Φ = π/2 Time Highest wavelength emitted depends on carrier-envelope phase Single-Attosecond pulse (650 as) -> Stable seed energy is only possible with phase controlled laser source

30 Phase Controlled Laser Pulses Electric field of a 1.5-cycle optical pulse E-Field, a.u Carrier-Envelope Phase even odd φ CE Field Envelope Time, fs L. Xu, et al., Opt. Lett. 21, 2008, (1996) Maximum field depends on φ CE

31 Octave, Prismless Ti:sapphire Laser 1mm BaF2 OC 1 PUMP Laser crystal: 2mm Ti:Al 2 O 3 φ = 10 ο L = 20 cm BaF2 - wedges Base Length = 30cm for 82 MHz Laser OC 2

32 Carrier-Envelope Phase and Frequency Metrology Spectrum 0 f CEO SHG f o -... f f o f o + f Optical Clocks Frequency Periodic Pulse Train with T R = 1 f T. Udem, et al., PRL 82, 3568 (1999) D. Jones, et al., Science 288, (2000) Provides an ultrastable modelocked pulse train! The clock of the Facility

33 Current HHG - Seed Generation (CPA) Slow carrierenvelope phase control loop FemtoMeter PC-DAC 5W-Verdi pump laser Sub-10 fs Ti:Sapphire seed-oscillator Pulse selector of pulses with equal phase 1-10 khz repetition rate Dazzler pulse shaper Ti:Sapphire amplifier, 1mJ, 1-10 khz Microstructure fiber based carrier-envelope phase control (Menlo-Systems) Femtopower-Pro 5m vaccum line High Harmonic Generation in jet or hollow or PBG fiber 0.5 mj Hollow fiber compressor, 5fs (optional) A. Baltuska, et al., Nature, 421, 611 (2003)

34 Attosecond X-ray Pump-Probe Spectroscopy τ Seed nj 10 6 X-FEL (Amplifier) τ Pump mj Direct observation of inner atomic and molecular processes on a sub-femtosecond time scale Other Applications: Direct nano-machining with x-ray pulses,