Presentation is loading. Please wait.

Presentation is loading. Please wait.

In Search of the “Absolute” Optical Phase Xiaoqin (Elaine) Li Ryan Smith Jessica Pipis Steve Cundiff Rich Mirin Tara Fortier David Jones Ravi Bhat John.

Similar presentations


Presentation on theme: "In Search of the “Absolute” Optical Phase Xiaoqin (Elaine) Li Ryan Smith Jessica Pipis Steve Cundiff Rich Mirin Tara Fortier David Jones Ravi Bhat John."— Presentation transcript:

1 In Search of the “Absolute” Optical Phase Xiaoqin (Elaine) Li Ryan Smith Jessica Pipis Steve Cundiff Rich Mirin Tara Fortier David Jones Ravi Bhat John Sipe JILA, NIST, CU (Boulder)U of T (Toronto) Pete Roos (JILA, NIST, CU)

2 Outline Important concepts and motivation How fast is ultrafast? The “Absolute” optical phase. Why do we care? Creation and control of ultrashort pulses Modelocking. “Absolute” phase evolution – time vs. frequency. Detection methods. Quantum interference control (QIC) in semiconductors Background. Concepts and theory. Experimental studies and stabilization using QIC.

3 How Fast is Ultrafast? Within an order of magnitude or two of 10 fs (1 fs = s). 1 s 1 fs Scaling example:

4 “Absolute” Optical Phase Carrier Envelope Pulse envelope provides “absolute” phase reference. Carrier-envelope (CE) phase Ultrafast optics approaching interesting regime: Optical carrier cycle (~ 3fs) Pulse Duration (~10 fs)

5 Why do we care? Not only control of intensity envelope … field. Optical waveform synthesis. AWG at optical frequencies. 2. Ultimate control of light. Extreme nonlinear optics. Photoionization and x-ray generation. Photoelectron emission from metal surfaces. Coherent control experiments. 1. Can a ffect light-matter interactions. 3. Precision measurements. Optical frequency metrology. Linear / nonlinear spectroscopy.

6 Outline Important concepts and motivation How fast is ultrafast? The “Absolute” optical phase. Why do we care? Creation and control of ultrashort pulses Modelocking. “Absolute” phase evolution – time vs. frequency. Detection methods. Quantum interference control (QIC) in semiconductors Background. Concepts and theory. Experimental studies and stabilization using QIC.

7 Short Laser Pulses External switch: Gain Mirrors Output beam Switch Pulses Internal switch: Gain Mirrors Switch Pulses

8 Ultrashort Laser Pulses Requires phase locked modes. Modelocking: Frequency Intensity Time Intensity 30 modes random phases 30 modes all in phase Coherent interference effect.

9 Output Coupler High Reflector Laser Cavity Free Space CE Phase Instability In laser cavity: v group ≠ v phase CE phase evolves from pulse to pulse outside cavity.

10 Random Evolution Uncontrolled CE phase evolution: Limits meaningful physics and applications.

11 No Evolution Fixed CE phase: Enables meaningful physics and applications.

12 Controlled Evolution Controlled CE phase evolution:  Also enables meaningful physics and applications.

13  ce Time vs. Frequency Domain I( ) 0 Frequency Domain Time Domain t E(t) F.T.  ce x2  ce  ce  ce  ce f rep   pp  p

14 Time vs. Frequency Domain Time Domain t E(t) 0 Frequency Domain I( ) F.T.   x2 +f 0 +f0+f0 +f0+f0 f0f0 f 0 =f rep 

15 Some Detection Methods Second harmonic generation ( -to-2 ) Telle et al., Appl. Phys. B (1999); Jones et al., Science 288, 635 (2000); Apolonski et al., PRL 85, 740 (2000) Rabi sideband interference Vu et al., PRL 92, (2004); Mücke et al., Opt. Lett (2004) Photoionization of gases Durfee et al., PRL (1999); Paulus et al., Science 414, 182 (2002) Photoelectron emission from metals Lemell et al., PRL 90, (2003); Apolonski et al., PRL 92, (2004)   semiconductor  Rabi metal vapor

16 Outline Important concepts and motivation How fast is ultrafast? The “Absolute” optical phase. Why do we care? Creation and control of ultrashort pulses Modelocking. “Absolute” phase evolution – time vs. frequency. Detection methods. Quantum interference control (QIC) in semiconductors Background. Concepts and theory. Experimental studies and stabilization using QIC.

17 Quantum Interference ~sin  a  b  c  d  aa bb cc dd ~sin        Two distinct quantum mechanical pathways. Connect same initial and final states. State population Shapiro et al, J Chem Phys 84, 4103 (1986) Atomic photoionization Yin et al, PRL 69, 2353 (1992) Molecular photodissociation Sheehy et al, PRL 74, 4799 (1995) Semiconductor spin currents Bhat et al, PRL 85, 5432 (2000) Semiconductor charge currents Haché et al, PRL 78, 306 (1997) Relative optical phase can coherently control:

18 QIC in Semiconductors Quantum interference between 1 and 2 photon absorption. Sensitive to relative phase between and 2  Asymmetry in momentum space  directional current. sin     Photocurrent direction and magnitude sensitive to CE phase.  sin  ce  ce  sin(  ce )  ce

19 QIC in Semiconductors { } Atanasov et al., PRL 76, 1703 (1996); Haché et al., PRL 78, 306 (1997) Velocity Charge Transition Amplitudes One-photonTwo-photon From Fermi’s Golden Rule:

20 QIC in Semiconductors {} One-photon absorption Two-photon absorption Atanasov et al., PRL 76, 1703 (1996); Haché et al., PRL 78, 306 (1997) Velocity Charge Transition Amplitudes Quantum Interference

21 QIC in Semiconductors {} One-photon absorption Two-photon absorption Quantum Interference Even in k

22 QIC in Semiconductors {} One-photon absorption Two-photon absorption Quantum Interference Even in k Odd in k

23 QIC in Semiconductors {} One-photon absorption Two-photon absorption Quantum Interference Even in k Odd in k

24 Simplified Setup Stabilized Ti:sapphire modelocked laser Split mirror  Time delay adjust Fiber broadening Lock-in amplifier I/V Lens Sample RF spectrum analyzer Prism ~15 fs, 93 MHz rep. rate, up to 400 mW avg. power LT-GaAs

25 Signal Amplitude Current ≈ 100 pA Now have >500 pA.

26 Incident Power ~ I  (I 2 ) 1/2 Roos et al., JOSA B (to be published)

27 CE Phase Sensitivity Verification that phase of QIC signal varies with shifts in carrier-envelope phase. Fortier et al., PRL 92, (2004)

28 Detection Bandwidth With transimpedance amplifier: 830 kHz. Roos et al., JOSA B (to be published)

29 Simplified Stabilization Setup Output coupler High reflector Pump Ti:sapphire crystal Prism Split mirror  Time delay adjust Fiber broadening Stabilization electronics I/V Lens Sample To phase noise analysis Ti:sapphire laser ~ Mixer Synthesizer

30 Stabilization via QIC CE phase evolution stabilized. Roos et al., Opt. Lett. (to be published)

31 Summary “Absolute” (carrier-envelope) phase: phase difference between carrier peak and envelope peak. Important for light-matter interactions, optical waveform synthesis, precision measurements. Modelocked lasers enable access to “absolute” phase. To detect: compare phase of spectral components in frequency domain through nonlinear process. Quantum interference control (QIC) in semiconductors gives phase-sensitive photocurrent. “Absolute” phase stabilization using QIC.


Download ppt "In Search of the “Absolute” Optical Phase Xiaoqin (Elaine) Li Ryan Smith Jessica Pipis Steve Cundiff Rich Mirin Tara Fortier David Jones Ravi Bhat John."

Similar presentations


Ads by Google