Proposal for a Solid State Carrier-Envelope-offset phase (CEP) detector
description
Transcript of Proposal for a Solid State Carrier-Envelope-offset phase (CEP) detector
Slide 1 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
Proposal for a Solid State Carrier-Envelope-offset phase (CEP) detector
June 10 2008Cole Van Vlack, Stephen Hughes
Queen’s University, Kingston ON
Acknowledgements:S.T. Cundiff, J.E. Sipe, and M. Wegener
Slide 2 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
Motivation• Modern ultrafast laser techniques now allow precise control
of the absolute carrier envelope offset phase (CEP)
• Fundamentally interesting to look at the influence of the CEP on ultrafast carrier dynamics in semiconductors
• Solid state CEP detectors are highly sought after by the ultrafast laser community, but still remain elusive
• Note: Absolute CEP is different from relative CEP (eg. work by Cundiff, Sipe & co.)
CEP
Slide 3 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
Background• While the CEP has been measured previously in atomic
systems (e.g., Krausz group,... PRL `03 and T.Nakajima, et al, Opt. Lett. `06) there are several restrictions
• For semiconductors, several ideas have been proposed for measuring the CEP, eg. Wegener group, Opt. Lett `04, using carrier wave Rabi flopping (Hughes PRL `98)
– These high intensity regimes are not reliable for measuring the CEP (eg. Van Vlack, Hughes, Opt. Lett. `06)
• Although the CEP has also been measured in a solid state system using a gold cathode (Krausz group,... PRL `04), there are issues of geometrical averaging
Slide 4 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
Proposed Scheme for CEP detector
eg. [P. C. Planken et al., PRL `92]
GaAs thin film (20 nm)
Sapphire substrate
5 fs pulse
Emitted Dipole Field
Dipole Polarization
Slide 5 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
Theory• Solved with 1D FDTD, without using SVEA• Includes propagation effects
• Includes Surface SHG (Wegener & co, Opt. Lett. `04)
Slide 6 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
Material Equations• Field coupled to semiconductor Bloch equations, w/o RWA
• Employ two band approximation• Use tight-binding model for bands (w/ GaAs parameters)• Included intraband relaxation
Slide 7 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
Coulombic Effects
• Rabi frequency , ! E0=3 GV/m (corresponds to Ipeak ¼ 1 TW, or a 2.6 pulse)
Unscreened due to slow buildup of screening on ~10fs timescales (Haug & co., PR B. `94)
• Time dependent , which includes excitation induced dephasing (eg. Haug & co., PRL. `99)
Slide 8 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
Nonlinear Field Spectra and Ultrafast Carrier Dynamics
=0
=/2
Slide 9 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
=0
=/2
Nonlinear Field Spectra and Ultrafast Carrier Dynamics with excitonic contribution
Slide 10 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
Phase Map of Emitted Spectra
With excitonic interactionWithout excitonic interaction
Slide 11 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
Summary
• We have proposed a setup in which the effects of the CEP can be measured
• We have observed CEP effects at intensities low enough as to be below carrier wave Rabi flopping
• We have shown that they are fairly robust within a certain intensity range, and show no qualitative differences when excitons are included
• Future work: More sophisticated band structure
Slide 12 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
Beyond the two band approximation
Slide 13 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
2
Slide 14 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
Phase maps in regime of CWRF
2.5 pulse 5 pulse
Slide 15 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
Phase maps in regime of CWRF in transmission
2.5 pulse 5 pulse
Slide 16 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
Nonlinear Field Spectra and Ultrafast Carrier Dynamics for small amplitudes
=0
=/2
Slide 17 (of 11) C. Van Vlack et al., CAP Congress, June, 2008
Nonlinear Field Spectra and Ultrafast Carrier Dynamics for 10 fs pulses
=0
=/2