Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multidimensional Coherent Photocurrent Spectroscopy of a Semiconductor
  Nanostructure   Multidimensional Coherent Optical Photocurrent Spectroscopy (MD-COPS) is
implemented using unstabilized interferometers. Photocurrent from a
semiconductor sample is generated using a sequence of four excitation pulses in
a collinear geometry. Each pulse is tagged with a unique radio frequency
through acousto-optical modulation ; the Four-Wave Mixing (FWM) signal is then
selected in the frequency domain. The interference of an auxiliary continuous
wave laser, which is sent through the same interferometers as the excitation
pulses, is used to synthesize reference frequencies for lock-in detection of
the photocurrent FWM signal. This scheme enables the partial compensation of
mechanical fluctuations in the setup, achieving sufficient phase stability
without the need for active stabilization. The method intrinsically provides
both the real and imaginary parts of the FWM signal as a function of
inter-pulse delays. This signal is subsequently Fourier transformed to create a
multi-dimensional spectrum. Measurements made on the excitonic resonance in a
double InGaAs quantum well embedded in a p-i-n diode demonstrate the technique.

25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
4
The categories of this paper are: cond-mat
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an