Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Enhanced Second-harmonic Generation Using Nonlinear Metamaterials   We demonstrate a nonlinear metamaterial which enhance higher order harmonics
in microwave frequency regime. Nonlinearity in the structure is introduced by
adding a varactor diode in the common slit of the double split ring resonator
(DSRR) design. By engineering the structure such that inner ring resonance
frequency of the DSRR is twice as the outer ring resonance frequency, we have
demonstrated that the second harmonic of the outer ring can be enhanced
significantly. By comparing with a single ring (SRR) unit cell structure, DSRR
has an enhancement factor of 70. Furthermore, we elucidate that the second
harmonic signals generated by two identical double split rings interfere and we
can use its constructive interference positions to construct an array of DSRRs
that gives a maximum second harmonic signal with phase matching condition. When
the phase matching condition occurs the enhancement factor of an array is more
than the contribution of individual unit cells which proves that the
enhancement is due to not only constructive interference of the second harmonic
generated by individual unit cells but also due to cavity mechanism occurred in
the array structure.

1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
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The categories of this paper are: q-fin
18
The categories of this paper are: econ
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
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The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int