Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Broadband sensitive pump-probe setup for ultrafast optical switching of
  photonic nanostructures and semiconductors   We describe an ultrafast time resolved pump-probe spectroscopy setup aimed at
studying the switching of nanophotonic structures. Both fs pump and probe
pulses can be independently tuned over broad frequency range between 3850 and
21050 cm$^{-1}$. A broad pump scan range allows a large optical penetration
depth, while a broad probe scan range is crucial to study strongly photonic
crystals. A new data acquisition method allows for sensitive pump-probe
measurements, and corrects for fluctuations in probe intensity and pump stray
light. We observe a tenfold improvement of the precision of the setup compared
to laser fluctuations, allowing a measurement accuracy of better than
$\Delta$R= 0.07% in a 1 s measurement time. Demonstrations of the improved
technique are presented for a bulk Si wafer, a 3D Si inverse opal photonic
bandgap crystal, and z-scan measurements of the two-photon absorption
coefficient of Si, GaAs, and the three-photon absorption coefficient of GaP in
the infrared wavelength range.

5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con