We report an irradiation sensor based on a fluorescent “flying particle” that is optically trapped and propelled inside the core of a water-filled hollow-core photonic crystal fiber. When the moving particle passes through an irradiated region, its emitted fluorescence is captured by guided modes of the fiber core and so can be monitored using a filtered photodiode placed at the fiber end. The particle speed and position can be precisely monitored using in-fiber Doppler velocimetry, allowing the irradiation profile to be measured to a spatial resolution of ∼10 μm. The spectral response can be readily adjusted by appropriate choice of particle material. Using dye-doped polystyrene particles, we demonstrate detection of green (532 nm) and ultraviolet (340 nm) light.

1.
C.
Fitzpatrick
,
C.
O'Donoghue
,
J.
Schöbel
,
B.
Bastiaens
,
P.
van der Slot
,
E.
Lewis
, and
D.
Pendrill
, “
A large core polymer optical fibre sensor for x-ray dosimetry based on luminescence occurring in the cladding
,”
Meas. Sci. Technol.
15
,
1586
1590
(
2004
).
2.
C.
Fitzpatrick
,
C.
O'Donoghue
, and
E.
Lewis
, “
A novel multi-point ultraviolet optical fibre sensor based on cladding luminescence
,”
Meas. Sci. Technol.
14
,
1477
(
2003
).
3.
D.
McCarthy
,
S.
O'Keeffe
,
E.
Lewis
,
D. G.
Sporea
,
A.
Sporea
,
I.
Tiseanu
,
P.
Woulfe
, and
J.
Cronin
, “
Radiation dosimeter using an extrinsic fiber optic sensor
,”
IEEE Sens. J.
14
,
673
685
(
2014
).
4.
M.
McSherry
,
C.
Fitzpatrick
, and
E.
Lewis
, “
An optical fiber sensor for the detection of germicidal UV irradiation using narrowband luminescent coatings
,”
IEEE Sens. J.
4
,
619
626
(
2004
).
5.
V. K.
Shinoj
and
V. M.
Murukeshan
, “
Hollow-core photonic crystal fiber based multifunctional optical system for trapping, position sensing, and detection of fluorescent particles
,”
Opt. Lett.
37
,
1607
(
2012
).
6.
D. S.
Bykov
,
O. A.
Schmidt
,
T. G.
Euser
, and
P. St.J.
Russell
, “
Flying particle sensors in hollow-core photonic crystal fibre
,”
Nat. Photonics
9
,
461
465
(
2015
).
7.
C.
Rajapakse
,
F.
Wang
,
T. C. Y.
Tang
,
P. J.
Reece
,
S. G.
Leon-Saval
, and
A.
Argyros
, “
Spectroscopy of 3D-trapped particles inside a hollow-core microstructured optical fiber
,”
Opt. Express
20
,
11232
(
2012
).
8.
F.
Gebert
,
M. H.
Frosz
,
T.
Weiss
,
Y.
Wan
,
A.
Ermolov
,
N. Y.
Joly
,
P. O.
Schmidt
, and
P. St.J.
Russell
, “
Damage-free single-mode transmission of deep-UV light in hollow-core PCF
,”
Opt. Express
22
,
15388
(
2014
).
9.
N.
Yamamoto
,
L.
Tao
, and
A. P.
Yalin
, “
Single-mode delivery of 250 nm light using a large mode area photonic crystal fiber
,”
Opt. Express
17
,
16933
(
2009
).
10.
W. P.
Leung
,
M.
Kulkarni
,
D.
Krajnovich
, and
A. C.
Tam
, “
Effect of intense and prolonged 248 nm pulsed-laser irradiation on the properties of ultraviolet-grade fused silica
,”
Appl. Phys. Lett.
58
,
551
553
(
1991
).
11.
T. G.
Euser
,
M. K.
Garbos
,
J. S. Y.
Chen
, and
P. St.J.
Russell
, “
Precise balancing of viscous and radiation forces on a particle in liquid-filled photonic bandgap fiber
,”
Opt. Lett.
34
,
3674
(
2009
).
12.
M. K.
Garbos
,
T. G.
Euser
,
O. A.
Schmidt
,
S.
Unterkofler
, and
P. St.J.
Russell
, “
Doppler velocimetry on microparticles trapped and propelled by laser light in liquid-filled photonic crystal fiber
,”
Opt. Lett.
36
,
2020
2022
(
2011
).
13.
E. A. J.
Marcatili
and
R. A.
Schmeltzer
, “
Hollow metallic and dielectric waveguides for long distance optical transmission and lasers
,”
Bell Syst. Tech. J.
43
,
1783
1809
(
1964
).
14.
N. H.
Bingham
and
J. M.
Fry
, “
Multiple regression
,” in
Regression
, Springer Undergraduate Mathematics Series (
Springer
,
London
,
2010
), pp.
61
97
.
15.
R. F.
Harrington
,
Time-Harmonic Electromagnetic Fields
(
McGraw-Hill
,
New York
,
1961
).
16.
P.
Uebel
,
M. C.
Günendi
,
M. H.
Frosz
,
G.
Ahmed
,
N. N.
Edavalath
,
J.-M.
Ménard
, and
P. St.J.
Russell
, “
Broadband robustly single-mode hollow-core PCF by resonant filtering of higher-order modes
,”
Opt. Lett.
41
,
1961
(
2016
).
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