1. Shaping Pulses Before They are Born Avi Pe’er Physics Department and BINA center for nano-technology, Bar Ilan University FRISNO 11 Shai Yefet, Naaman Amer ₪ - ISF, Kahn Foundation

2. Outline Why pulse shaping Standard techniques ◦ Mode locked oscillator cavity ◦ Extra-cavity shaping Intra cavity shaping – why not ? Gain shaping concept Results Conclusions

3. Pulse Shaping In Optics Control a pulse shape in time / spectrum Coherent quantum control Precision spectroscopy using frequency comb PRL 98, 113004 (2007) Label free Fluorescence microscopy with Stimulated Raman Science 322, 1857-1860 (2008). Frequency domain picture Pump Dump τ vib t rep PumpDump Time domain picture

4. Standard Mode Locked Cavity (Ti:S) OC HR gain medium Pump source @ 532 nm Mode competition (Gain, Loss, Dispersion) No knob on spectrum

5. Kerr Lens Mode Locked Cavities 1 st stability limit - Telescope 2 nd stability limit

6. Pulse Shaping (Extra-Cavity) Phase modulation: Simple, lossless Amplitude modulation: Lossy ! SLM

7. Intra Cavity Pulse Shaper ? OC HR gain medium Pump source @ 532 nm In cavity phase = frequency shift No phase shaping ! Amplitude shaping = loss shaping Mode competition ! Two Colors – Impossible !

8. Two-Colors so far ? Active locking of independent lasers Opt. Lett. 27, 312 (2002) Passive Locking – shared Kerr medium Opt. Lett. 29, 629 (2004) OPO – signal and idler Synchronously pumped OPOs Time lens technique - Active modulation of a CW laser Optics Express 18, 24019 (2010)

9. Gain Shaping Spatial shaper OC HR 1st gain medium 2nd gain medium Beam splitter Pump source @ 532 nm Spatial shape of pump = Spectral shape of gain

10. Results I Power (a.u.) 100 80 60 40 20 0 Wavelength (nm) 680 930 840 765 745

11. Results II

12. Conclusions Multi lobed spectra in mode locked oscillators are important for many applications No easy solution so far – Synchronization of independent sources Gain shaping allows for arbitrary control of the oscillation spectrum.