Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Wavelength Conversion Efficiency Enhancement in Modal Phase Matched
  $\chi^{(2)}$ Nonlinear Waveguides   Modal phase matching (MPM) is a widely used phase matching technique in
Al$_x$Ga$_{1-x}$As and other $\chi^{(2)}$ nonlinear waveguides for efficient
wavelength conversions. The use of a non-fundamental spatial mode compensates
the material dispersion but also reduces the spatial overlap of the three
interacting waves and therefore limits the conversion efficiency. In this work,
we develop a technique to increase the nonlinear overlap by modifying the
material nonlinearity, instead of the traditional method of optimizing the
modal field profiles. This could eliminate the limiting factor of low spatial
overlap inherent to MPM and significantly enhance the conversion efficiency.
Among the design examples provided, this technique could increase the
conversion efficiency by a factor of up to $\sim$290 in an Al$_x$Ga$_{1-x}$As
waveguide. We further show that this technique is applicable to all
$\chi^{(2)}$ material systems that utilize MPM for wavelength conversion.

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The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
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The categories of this paper are: ao-sci
2
The categories of this paper are: math
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The categories of this paper are: atom-ph
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The categories of this paper are: econ
10
The categories of this paper are: q-bio
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The categories of this paper are: mtrl-th
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The categories of this paper are: astro-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: alg-geom
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The categories of this paper are: gr-qc
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-fin