Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Second-order coherence properties of amplified spontaneous emission from
  a high-power tapered superluminescent diode   We study the degree of second-order coherence of the emission of a high-power
multi-quantum well superluminescent diode with a lateral tapered amplifier
section with and without feedback. When operated in an external cavity, the
degree of second-order coherence changed from the almost thermal case of
g$^{(2)}$(0)$\approx$1.9 towards the mostly coherent case of
g$^{(2)}$(0)$\approx$1.2 when the injection current at the tapered section was
increased. We found good agreement with semi-classical laser theory near and
below threshold while above laser threshold a slightly higher g$^{(2)}$(0) was
observed. As a free running device, the superluminescent diode yielded more
than 400 mW of optical output power with good spatial beam quality of
$M^2_{slow} < 1.6$. In this case, the DSOC dropped only slightly from 1.9 at
low powers to 1.6 at the maximum output power. To our knowledge, this is the
first investigation of a high-power tapered superluminescent diode concerning
the degree of second-order coherence. Such a device might be useful for
real-world applications probing the second order coherence function, such as
ghost imaging.

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The categories of this paper are: comp-gas
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The categories of this paper are: adap-org
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The categories of this paper are: patt-sol
4
The categories of this paper are: cond-mat
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-th
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The categories of this paper are: nlin
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The categories of this paper are: cmp-lg
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The categories of this paper are: math-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: gr-qc
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The categories of this paper are: math
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The categories of this paper are: solv-int
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The categories of this paper are: cs
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The categories of this paper are: funct-an
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The categories of this paper are: eess