Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High resolution optical time domain reflectometer based on 1.55um
  up-conversion photon-counting module   We implement a photon-counting Optical Time Domain Reflectometer (OTDR) at
1.55um which exhibits a high 2-point resolution and a high accuracy. It is
based on a low temporal-jitter photon-counting module at 1.55um. This detector
is composed of a periodically poled Lithium niobate (PPLN) waveguide, which
provides a wavelength conversion from near infrared to visible light, and a low
jitter silicon photon-counting detector. With this apparatus, we obtain
centimetre resolution over a measurement range of tens of kilometres.

29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg