Events
Event Overview
Frequency Domain Nonlinear Optics
Speaker: François Légaré
Date & Time: September 1, 2016 11:00 - 12:15
Location: AMPEL 311
Local Contact: Andrea Damascelli
Intended Audience: Graduate
The universal dilemma of gain narrowing occurring in fs amplifiers prevents ultra-high power
lasers from delivering few-cycle pulses. This problem is overcome by a new amplification concept:
Frequency domain Optical Parametric Amplification – FOPA [1,2]. It enables simultaneous upscaling
of peak power and amplified spectral bandwidth and can be performed at any wavelength
range of conventional amplification schemes, however, with the capability to amplify single cycles
of light.
The key idea for amplification of octave-spanning spectra without loss of spectral
bandwidth is to amplify the broad spectrum “slice by slice” in the frequency domain, i.e. in the
Fourier plane of a 4f-setup [3]. Opposed to traditional schemes where amplification takes place in
time domain, we propose to amplify different spectral parts independently of each other in the
spectral domain. Therefore, the pulse’s input spectrum is spectrally dispersed and then several
individual narrowband optical parametric crystals are used whereby each is tuned for optimal
amplification of its corresponding spectral slice.
The striking advantages of this scheme, are its capability to amplify (more than) one octave
of bandwidth without shorting the corresponding pulse duration. This is because ultrabroadband
phase matching is not defined by the properties of the nonlinear crystal employed but the number
of crystals employed. In the same manner, to increase the output energy one simply has to increase
the spectral extension in the Fourier plane and to add one more crystal. Thus, increasing pulse
energy and shortening its duration accompany each other.
A proof of principle experiment was carried out at the Advanced Laser Light Source
(ALLS) on the sub-two cycle IR beam line [4] and yielded record breaking performance in the
field of few-cycle IR lasers. 100μJ two-cycle pulses from a hollow core fibre compression setup
were amplified to 1.43mJ without distorting spatial or temporal properties. Pulse duration at the
input of FOPA and after FOPA remains the same. Recently, we have started upgrading this system
to be pumped by 250 mJ to reach 40 mJ two-cycle IR few-cycle pulses and latest results will be
presented. Furthermore, the extension of the FOPA approach to other nonlinear optical processes
will be discussed.
References
[1] B. E. Schmidt, N. Thiré, M. Boivin, A. Laramée, F. Poitras, G. Lebrun, T. Ozaki, H. Ibrahim,
and F. Légaré, “Frequency domain optical parametric amplification.,” Nature Commun. 5,
3643 (2014).
[2] P. Lassonde, N. Thiré, L. Arissian, G. Ernotte, F. Poitras, T. Ozaki, A. Laramée, M. Boivin, H.
Ibrahim, F. Légaré, and B. E. Schmidt, “High gain Frequency domain Optical Parametric
Amplification”, IEEE JSTQE, in press (2015).
[3] A. M. Weiner, “Femtosecond optical pulse shaping and processing,” Progr. Quant. Electr. 19,
161-237 (1995).
[4] B. Schmidt, A. Shiner, P. Lassonde, J. Kieffer, P. B. Corkum, D. M. Villeneuve, and F. Légaré,
“CEP stable 1.6 cycle laser pulses at 1.8 μm,” Opt. Express 19, 6858-6864 (2011).