The document discusses femtosecond lasers and optical frequency combs and their applications. It describes how carrier envelope phase control allows generation of optical arbitrary waveforms. Frequency combs have enabled advances in optical clocks and precision sampling. Applications include spectroscopy, imaging, and communications. The author discusses using integrated modulators to generate complex waveforms spanning multiple octaves.

1. Clocks, Combs and OAWG Erich P. Ippen Massachusetts Institute of Technology Cambridge, MA 02139 [email_address] NEOSA September 15, 2011 MIT Optics and Quantum Electronics

2. Outline Femtosecond lasers – few cycle pulses Carrier envelope phase control Optical frequency combs Arbitrary optical waveforms Applications Clocks Precision sampling and timing MIT Optics and Quantum Electronics

3. The 5-fs Ti:sapphire Laser Kerr lens modelocking (KLM) Double-chirped mirrors All-solid state, prismless cavity 5 fs = less than 2 cycles Octave-spanning spectrum MIT Optics and Quantum Electronics

4. Under Each Pulse is a Short Waveform The electric field waveform slips under the envelope from pulse to pulse – if group delay and phase delay differ. Carrier-envelope phase slip  2n G L/c MIT Optics and Quantum Electronics BBO 570 nm filter PBS RF spectrum analyzer PMT Second harmonic generation

5. Control Over the Optical Phase Carrier-envelope phase stabilization An optical clockwork ! The optical frequency is an exact multiple of the pulse rep-rate. MIT Optics and Quantum Electronics

6. A Clock an oscillator a clockwork Pendulum - Christiaan Huygens 1656 Chronometer - John Harrison (H4) 1761 (10 -6 ~ 1 sec/ 9 days ) Quartz - W. Marrison, Bell Labs, 1928 (10 -8 ~ 1 sec/3yrs ) Cesium atom - 1955 (10 -10 ~ 1sec/300yrs) Hg ion – 5x10 -18 ~ 10sec since big bang Atomic fountain - NIST-F1 (1.7x10 -15 ~ 1sec/20Myrs) and MIT Optics and Quantum Electronics

7. Clockwork by Frequency Multiplication From the 9.192 GHz Cs frequency standard to the 456 THz (657nm) Ca transition 1999 10 -14 accuracy 10 lasers 8 phase-lock loops MIT Optics and Quantum Electronics

8. The Clockwork in the Frequency Domain 1f-to-2f frequency locking Octave-spanning frequency comb This locks the rep rate to the optical frequency. Still need an optical reference. MIT Optics and Quantum Electronics laser modes exact multiples of f rep 2 nd harmonics

9. Locking to the 3.39  m HeNe Reference via DFG He-Ne/CH 4 Laser 3.39  m Transportable Stability ~ 10 -14 Difference frequency generation in PPLN DFG MIT Optics and Quantum Electronics

12. Optical Arbitrary Waveform Generation (OAWG) Amplitudes and phases of all these frequencies are now determined. How about: MIT Optics and Quantum Electronics

13. Completely Arbitrary Waveforms Fast modulator array Spectrum locked to “absolute” grid Arbitrary electrical field waveform ! Pulse-to-pulse AM & PM Arbitrary spectrum MIT Optics and Quantum Electronics f t

15. InP Encoder: 10channel 14.2 mm UC Davis S.J. Ben Yoo et al. Trial output waveforms 10.7 mm PM AM MIT Optics and Quantum Electronics

16. Packaged InP OAWG (10 Ch AM+ 10 Ch PM) x 10 GHz InPhi & UC Davis MIT Optics and Quantum Electronics

20. GHz Er:Fiber Laser Technology MIT Optics and Quantum Electronics

25. 1 GHz Octave-Spanning 1µm-2µm Continuum 1012nm 7.09mW 2024nm 65.37mW 1 GHz Source 1 GHz Supercontinuum 1082nm 8.56mW 1590nm 47.02mW 1f-2f DFG MIT Optics and Quantum Electronics

28. Precision Sampling for ADC G.C. Valley, Opt.Exp. 15, 1955 (2007) R. H. Walden IEEE J.Sel.Areas in Comm 17, 539 (1999) ADC limited by timing jitter in sampler The Walden Wall MIT Optics and Quantum Electronics

30. Synchronization of a Large Scale X-Ray FEL Kim et al., MIT/DESY MIT Optics and Quantum Electronics

31. Acknowledgments Andrew Benedick Hyunil Byun Jeff Chen David Chao Jonathan Morse Michelle Sander Jason Sickler Franz Kärtner Noah Chang Jung-Won Kim MIT Optics and Quantum Electronics

33. Linearly Chirped Waveform – 100 Modes 100 x 10GHz (1ps pulses), Supergaussian amplitude apodized 27  quadratic phase Chirp over timeslot - 1THz/100ps Spectral domain Time domain – chirped pulse Phase vs. time Chirp Amplitude Initial vs. chirped pulse MIT Optics and Quantum Electronics

34. Linearly Chirped Waveform 10-Modes Blue Curve – Target Intensity Black Curve -- Measured Intensity Blue dots – Target Phase Red Curve – Measured Phase Circles – Target Intensity Black Stems -- Measured Intensity Blue X – Target Phase Red Dots – Measured Phase Experiment MIT Optics and Quantum Electronics