Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fabrication of an integrated high-quality-factor (high-Q) optofluidic
  sensor by femtosecond laser micromachining   We report on fabrication of a microtoroid resonator of a high-quality factor
(i. e., Q-factor of ~3.24x10^6 measured under the critical coupling condition)
integrated in a microfluidic channel using femtosecond laser three-dimensional
(3D) micromachining. Coupling of light into and out of the microresonator has
been realized with a fiber taper that is reliably assembled with the
microtoroid. The assembly of the fiber to the microtoroid is achieved by
welding the fiber taper onto the sidewall of the microtoroid using CO_2 laser
irradiation. The integrated microresonator maintains a high Q-factor of
3.21x10^5 as measured in air, which should still be sufficient for many sensing
applications. We test the functionality of the integrated optofluidic sensor by
performing bulk refractive index sensing of purified water doped with tiny
amount of salt. It is shown that a detection limit of ~1.2x10^-4 refractive
index unit can be achieved. Our result showcases the capability of integration
of high-Q microresonators with complex microfluidic systems using femtosecond
laser 3D micromachining.

34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
4
The categories of this paper are: cond-mat
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
35
The categories of this paper are: mtrl-th