Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Determination of the Carrier-Envelope Phase of Few-Cycle Laser Pulses
  with Terahertz-Emission Spectroscopy   The availability of few-cycle optical pulses opens a window to physical
phenomena occurring on the attosecond time scale. In order to take full
advantage of such pulses, it is crucial to measure and stabilise their
carrier-envelope (CE) phase, i.e., the phase difference between the carrier
wave and the envelope function. We introduce a novel approach to determine the
CE phase by down-conversion of the laser light to the terahertz (THz) frequency
range via plasma generation in ambient air, an isotropic medium where optical
rectification (down-conversion) in the forward direction is only possible if
the inversion symmetry is broken by electrical or optical means. We show that
few-cycle pulses directly produce a spatial charge asymmetry in the plasma. The
asymmetry, associated with THz emission, depends on the CE phase, which allows
for a determination of the phase by measurement of the amplitude and polarity
of the THz pulse.

21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
14
The categories of this paper are: math-ph