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Fiber temperature sensor utilizing a
thermomechanical MEMS detector
H. Ozan Çirkinoğlu, Habib Bilgin, Fehmi Çivitci, Hamdi Torun, and Onur Ferhanoğlu
Abstract—We propose a novel fiber sensor utilizing a
thermomechanical MEMS element at the fiber tip. Owing to its
Parylene/Titanium bimaterial structure, the MEMS membrane
exhibits an out-of plane displacement with changing temperature.
Together with the MEMS element, the embedded diffraction
grating forms an in-line interferometer, from which the
displacement as well as the temperature can be deduced. The
fabricated detector is placed at the single-mode fiber output that
is collimated via a graded index lens. This novel architecture
allows for integrating MEMS detectors on standard optical
fibers, and easy substitution of the MEMS detector element to
alter the measurement range and the response time of the sensor.
Temperature and time-constant measurements are provided and
verified with reference measurements, revealing a temperature
sensitivity better than 20 mK temperature sensitivity and 2.5
msec response time, using low-cost laser source and
photodetectors.
Index
Terms—Optical
Microelectomechanical devices,
Optical device fabrication
fiber
Temperature
applications,
measurement,
I. INTRODUCTION
F
iber optic temperature sensors offer robust measurements
at harsh settings and measurement sites that are difficult to
access, owing to their small size and flexibility. Thanks to
their dielectric composition, these sensors are also immune to
electromagnetic radiation, making their use appealing for both
industrial (monitoring temperatures in circuits, civil structures,
and process control) and medical (monitoring temperature
during magnetic resonance imaging, microwave hyperthermia,
laser ablation) applications [1-3].
Interferometry has been a key detection technique
employed in fiber optic temperature sensors. Various types of
interference based schemes have been demonstrated, including
but not limited to fiber bragg gratings [4-5], Mach-Zehnder
interferometry, Fabry-Perot interferometry [6-7] , Sagnac
interferometry [8], and ring resonators [9].
Manuscript received, 2015; revised 2015, accepted 2016. Date of
publication 2016. This work was supported by the Scientific and
Technological Research Council of Turkey (TUBİTAK) under grant
114C077.
H. Ozan Çirkinoğlu, Fehmi Çivitci, and Onur Ferhanoğlu (email:
ferhanoglu@itu.edu.tr) are with the Electronics and Communication
Engineering Department of Istanbul Technical University, Istanbul, Turkey.
Habib Bilgin and Hamdi Torun (email: hamdi.torun@boun.edu.tr) are with
the Electrical and Electronics Engineering Department of Boğaziçi University,
Istanbul, Turkey.
Color versions of one or more of the figures in this paper are available
onlineat http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/JLT.2015.2436816
In an effort to further improve detection sensitivity,
Microelectromechanical System (MEMS) structures have been
fabricated on fiber tips as the moving arm of a Fabry-Perot
interferometer, at the expense of fabrication complexity. Here,
we propose a novel fiber optic temperature sensor architecture,
where a passive thermomechanical MEMS detector, with an
embedded diffraction grating, is coupled with a standard
single-mode optical fiber (Fig. 1).
Thermomechanical MEMS detectors have successfully
been utilized in thermal (Infrared) imaging applications,
providing temperature detection on the remote target with
100-200 mK sensitivity level, corresponding to sub-mK level
detection sensitivity on the detector itself [11–13].
Furthermore, MEMS detectors exploiting embedded
diffraction gratings have exhibited unprecedented detection
sensitivities in a variety of applications, such as atomic force
microscopy [13], biomolecular mechanics measurement
probes [14], and optical microphones [15]. Our temperature
sensing approach harnesses the combined benefits of i) using
passive MEMS elements with high thermomechanical
sensitivity, and ii) diffraction grating-based in-line
interferometric readout.
Fig. 1 illustrates the schematic drawing of the proposed
fiber temperature sensor. Narrow-band light source emitted
from a fiber is collimated via a graded index (GRIN) lens. The
ferrule that is surrounding the GRIN lens acts both as a
platform for the MEMS element and as a spacer to permit the
0th order light to couple back into the fiber while eliminating
other orders. The MEMS detector is defined as a bimaterial
structure, which bends in response to temperature change due
to thermal mismatch. A metallic cap (not shown in Fig. 1), on
top of the MEMS, is envisioned to provide a protection for the
membrane, also making the entire sensor system leak proof in
fully immersed applications. The metallic cap further provides
a thermal conduction path between
the surrounding
environment and the MEMS element. The MEMS element is a
simple square frame anchored to its substrate via four short
supports. All sensor components can be encapsulated within
0.5-1 mm diameter, given the availability of fiber optics and
GRIN lens components with < 250 µm diameter.
Towards realizing the proposed temperature sensor
architecture, here we demonstrate proof-of-principle testing of
our design via air coupling of the fabricated MEMS element
with the GRIN collimated fiber, and light detection at both
proximal and distal fiber ends.
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sensor distance (dGRIN), to isolate 1st and higher diffracted
orders from coupling back into the fiber as:
Fig 1. Proposed fiber optic temperature sensor architecture:
Thermomechanical MEMS element that bends in response to temperature,
together with the diffraction grating (shown underneath MEMS) form an inline interferometer. Temperature is measured through monitoring the 0th order
diffracted light, which is re-coupled back into the fiber.
II. MEMS DESIGN
A variety of thermomechanical sensor structures have been
presented in the literature, exhibiting crab-leg [16] , multilayered [17], and multi-joint [12] architectures. In this study,
the Thermomechanical MEMS detector is designed as a
simple, table-shaped structure that allows for a high-yield
microfabrication process and robust performance.
The thermomechanical response and speed of the device
can be tailored through altering the membrane and leg
geometries (thickness and width), respectively. Design and
fabrication effort focused on square framed devices, having 1mm width. Parylene and Titanium material were chosen as the
bimaterial pair. As the structural material, parylene, offers a
very high coefficient of thermal expansion (CTE) that enables
high thermomechanical sensitivity. Highly reflective metals
are preferred for fabricating the diffraction gratings and the
reflector on the membrane, in order to achieve high fringe
contrast. Though titanium offers worse reflectivity as opposed
to other metals, its low CTE together with superior adhesion
capability onto parylene, makes it an ideal choice for the
MEMS membrane.
The thickness of the parylene layer was chosen as 2 µm to
mitigate cracking that is induced due to thermomechanical
stress during fabrication. Furthermore, the 2 µm thick parylene
layer results in a mechanical resonance (0th order mode)
frequency of 5.5 kHz, ensuring the tolerance of the device to
environmental vibrations. Fig 2. illustrates the finite element
modeling (FEM) results, showing the deflection of a 1-mm
wide table-type MEMS element, with respect to the thickness
of deposited titanium layer on parylene. Maximum deflection
is achieved for 200-300 nm thick titanium, deposited on 2 µm
parylene. The thermomechanical displacement profile of the
MEMS element for 200 nm-thick titanium and 2 µm-thick
parylene layers, is illustrated in Fig 2b.
The grating period was chosen as 10 µm, for a costeffective mask printing and fabrication process. The grating
period determines the reflection angle of the 1st order
diffracted beam (θ1st = λ/Λ) and the minimum GRIN lens-
Fig 2. Thermomechanical FEM Analysis of a 1-mm wide table-shaped MEMS
element (having 200 µm wide, 5 µm long legs). a) Center displacement as a
function of titanium thickness, for 2 µm thick parylene structural layer. b)
Sensor displacement contour map, for 200 nm-thick titanium.
!!"#$ >
!!
2!
(1)
where D is the diameter of the collimating GRIN lens, λ is the
laser wavelength, and Λ is the grating period. For the
parameters used in this study (given in experimental results
section), the minimum distance between the collimation
assembly and the MEMS is calculated as 14.3 mm. The
fabrication process and illumination wavelength can be
tailored to significantly reduce the spacing between the GRIN
lens and the MEMS device that is crucial in maintaining the
flexibility of the sensor. The grating period can be reduced
down to 2 µm (1 µm line-width) using standard lithography
techniques, which would reduce the distance between the
GRIN lens and the MEMS device to less than 3 mm. Using
near Infrared wavelength for illumination would further
reduce the spacing.
III. MEMS FABRICATION
MEMS sensors were fabricated at the Microfabrication
Facility of the Center of Life Sciences and Technologies
(Boğaziçi University, Istanbul). The fabrication process,
illustrated in Fig. 3, uses a simple 4-mask process using
standard MEMS processes. The fabrication starts with the
definition of a titanium layer on a transparent quartz substrate
using a lift-off process. The titanium layer with a thickness of
200 nm is sputtered on a patterned layer of photoresist (AZ
4533 with a thickness of 1.3 µm) to form the diffraction
gratings. After stripping the photoresist, the sacrificial layer is
defined using the second mask. Another layer of photoresist
(AZ 4533 with a thickness of 5 µm) is used to define the
sacrificial layer. The sacrificial layer is baked at 115 °C for 50
s to prevent out-gassing problem in the subsequent steps. The
anchors are defined in this step. Then, a parylene layer with a
thickness of 2 µm is deposited as the structural layer of the
device. The parylene layer is deposited at room temperature
using a chemical vapor deposition process, followed by the
sputtering of the top titanium layer to form the bimaterial
structure. The thickness of the titanium layer is 200 nm and
the process of sputtering is completed at room temperature.
Then, the top titanium layer is masked using the third mask.
The soft and hard baking steps for the photolithography are
completed at 70 °C to prevent cracking on the parylene layer.
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independently. Both MEMS and digital thermometer sensors
were placed equidistant from the soldering iron. The
thermomechanical response of the MEMS sensor was
calculated based on the intensity change at both
photodetectors, while the temperature sensor chip measured
the absolute temperature. The thermal time constant of the
MEMS sensor was also measured using a fast heat source.
This was achieved by replacing the soldering iron with a high
power laser (50 mW power, λ=532 nm wavelength) that is
directed towards the sensor and chopped periodically at high
speed. The green laser beam was attenuated to provide 150
µW power to the MEMS sensor. The outputs of both
photodetectors were monitored using a multi-channel
oscilloscope (Tektronix MSO 4104), whereas the digital
thermometer chip was monitored using an Arduino (UNO R3)
platform that was connected to a personal computer.
Fig 3. Fabrication of MEMS sensors: a) 4 fabrication steps: definition of
grating layer, deposition and patterning of sacrificial photoresist, deposition
and patterning of structural parylene and titanium, release. b) SEM image of
fabricated 1 mm-wide sensor having square frame.
The titanium layer is wet etched using a diluted HF solution,
which is followed by another photolithography layer to mask
the Parylene layer. The Parylene layer is etched using oxygen
plasma. The etch rates of Parylene and photoresist are
identical in oxygen plasma. So, the thickness of the photoresist
mask is adjusted to be 4 µm for effective masking. Oxygen
plasma process defines the device structure on its sacrificial
layer. Finally, the sacrificial layer is etched using acetone and
released using a customized super-critical drying setup. Fig.
3b illustrates Electron microscopy image of the 1- mm width
table-shaped device.
IV. EXPERIMENTAL RESULTS
The characterization of the MEMS sensor was performed
using the setup that is illustrated in Fig. 4. A laser diode
(Thorlabs CPS196), 635 nm in wavelength and 1 mW in
power, was coupled into a single mode fiber, having a GRIN
fiber collimator at its distal end (Thorlabs 50-630-FC), via an
objective lens (0.25 NA, 10x magnification). The GRIN
collimator having 1.8 mm clear aperture, provides a beam with
full-width half maximum (FWHM) diameter of 0.5mm.
Considering coupling efficiency and transmission losses in our
system, the laser power arriving at the MEMS-based sensor is
measured as 30 µW.
A table-framed MEMS sensor with a width of 1 mm was
placed in front of the GRIN collimated fiber exit, at a distance
of ~4 cm to isolate higher diffracted orders so that only the
reflected beam is re-coupled back into the fiber. The MEMS
sensor was placed on a two-axes tilt stage to ensure efficient
coupling of the 0th diffracted order back into the fiber, which
is monitored using a photodetector (Thorlabs PDA36A) that is
placed at the proximal end of the fiber. The 1st order diffracted
light was also monitored at the distal end with another
photodetector of the same type. The functionality of the
MEMS sensor was tested using a soldering iron that was
placed at 3 mm distance from the sensor. A digital
thermometer chip (maxim DS18B20) was also placed right
next to the MEMS sensor to monitor the temperature
Fig 4. Experimental setup: Laser diode is coupled into fiber through 2
mirrors (M1, M2) and an objective lens (OBJ). The laser exiting the
fiber is collimated via GRIN lens. Intensity change of the diffracted
orders with applied temperature was monitored through
photodetectors that were placed at the proximal (PD1) and distal
(PD2) ends of the fiber. Temperature measurements were validated by
a reference temperature sensing chip (REF).
Fig. 5a illustrates the acquired 0th and 1st order laser
intensities (with 60 dB and 70 dB photodetector gains for PD1
and PD2, respectively), undergoing heating and cooling
cycles. The temperature of the soldering iron was increased by
200 oC during the heating cycle (0-200 seconds) and then
turned off during the cooling cycle of the experiment (200-400
seconds). The outputs of both detectors revealed about 5
fringes, in response to the temperature increase. The wellknown formulas for 0th and 1st diffraction order intensities (I0,
I1) as a function of sensor displacement (d), and input laser
intensity (Iin) are given as [18]:
!
(2)
!! = !!" (0.5cos 4!
+ 0.5)
!
4
!
(3)
!!" (0.5 − 0.5cos 4! )
!
!
!
th
Above formulas exhibit the intensity behavior of 0 and 1st
order diffracted light under ideal conditions considering; 50%
grating duty cycle (D), matching reflectivities for the
diffraction grating (R1) and the sensor reflector (R2), and a
perfect out-of-plane pumping motion of the sensor. On the
other hand, practically neither of these conditions are
!! =
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achieved, resulting in amplitude modulation and DC bias on
the diffracted order signals, as observed in Fig. 5a. The
diffracted order intensities under non-ideal conditions were
previously derived [19], as a function of sensor tilt and duty
cycle. The 0th order intensity further suffers from the
additional DC bias introduced due to reflections from other
components (beam splitter, objective lens) within the setup.
The spurious noise observed at the 0th order intensity is due to
the external vibrations, which decrease the coupling efficiency
of reflected light into the fiber. The integration of the MEMS
element onto the GRIN collimated fiber is expected to
mitigate the noise on 0th diffraction order.
Fig. 5b illustrates the calculated total displacement based on
0th and 1st order intensity data. The unambiguous detection
range of an interferometer output is λ/4, after which the
intensity values repeat themselves. Here, the displacement
calculation took place through deducing the relative
displacements of each quarter cycle (corresponding to λ/4
displacement). The deduced displacements were additively
stitched during the heating cycle, and subtracted from the total
displacement for the cooling cycle. The algorithm used to
calculate the total displacement is analogous to a typical phase
unwrapping algorithm. The calculations reveal a total
displacement of 1500 nm for the heating cycle. With the
addition of a secondary laser source, having slightly different
wavelength that could still be accommodated by the fiber, the
true displacement can be deduced based on two-wavelength
interferometry [20]. The two-wavelength interferometry
algorithm utilizes diffraction order intensity formulas to
calculate the displacement based on the outputs of two
sources. Note that, the secondary laser could be introduced
using an extra beam splitter within the incoming beam path,
however optical filters would be required in front of the
photodetectors to isolate the sources.
In Fig 5b, the temperature data acquired by the reference
sensor is overlaid on the 0th and 1st order intensity data. The
temperature behavior matches fairly well with the 0th and 1st
order intensity data, given that the speed of heating is mainly
dictated by the heat transfer from the soldering iron to the
sensors, and is independent from the response time of the
MEMS and reference sensors. Though general heating and
cooling trend exhibits similar behavior for the proposed sensor
and the reference sensor, there are instances (around t = 50s
and t = 400s) where a difference of up to ~0.2 oC is observed.
We attribute this error to the resolution (0.1 oC) and the
accuracy (± 0.5 oC) of the reference sensor, as cited by maxim
integrated [21], together with spurious vibrations induced on
our air-coupled setup.
The 1.8 oC temperature increase, observed for 1500 nm
MEMS sensor displacement, results in an experimental
thermomechanical sensitivity of 833 nm/ K, which is in good
agreement with the FEM simulation results (Fig. 2b). The
temperature measurement was also repeated with a K-type
bare thermocouple (FLUKE) to observe the absolute
temperature jump within the heating cycle, with which a
similar temperature increase was observed, indicating that the
package of the digital thermometer chip had minor influence
on the measurement result. Note that any difference between
the temperatures experienced by the reference sensor and the
MEMS membrane will directly affect the sensitivity
4
calculation. For the calculations below, we assume equal
temperature increase for the thermometer chip and the MEMS
detector. The temperature sensitivity (δT) is calculated based
on the ratio of total temperature increase (ΔT) to the signal-tonoise ratio (SNR):
Δ!
Δ!
!" =
=
(4)
!"# !"/δ!
where SNR value is calculated based on the ratio of amplitude
(Δd) and the root-mean-square noise (δd) of the deduced
displacement from the 0th order diffracted output. Based on the
quiescent interval at the first 4 seconds of the heating cycle,
the displacement noise is calculated as δd ≈ 16 nm. For ΔT =
1.8 K, Δd = 1500 nm, and δd = 16nm, the temperature
sensitivity of the sensor is calculated as: δT = 19 mK, based
on Eq. 5. The 0th order intensity (Fig 5a) exhibits increased
noise (3-4 folds) towards the end of the heating cycle (t = 150200s), caused by external vibrations. The noise, observed
when the temperature reaches its steady state, will be
mitigated upon integration of the MEMS detector on the fiber.
Fig 5. Thermomechanical response of the 1-mm wide MEMS sensor.
a) 0th and 1st order intensity in response to heating (0-200 seconds)
and cooling (200-400 seconds) cycles. b) Calculated displacement
based on a), in comparison to the reference temperature
measurements. c) Response of the MEMS sensor to laser actuation.
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Upon integration of the MEMS and the fiber, we further
expect the displacement noise to decrease to that of the 1st
diffraction order (δd = 5nm), improving the resolution to δT =
6 mK. The temperature range of the MEMS sensor (<T>), is
mainly limited by the gap between the structural layer and the
substrate (g), such that
!
< ! >= ±
(5)
Δ!/Δ!
where Δd/ΔT is the thermomechanical sensitivity of the sensor.
The 5 µm sensor gap corresponds to a temperature range of
±6 oC. Measurement range of ± 6 degrees is relevant to certain
applications (conducting implant safety experiments within
magnetic resonance imagers [22], [23]), while it poses a limit
for other applications. The temperature sensitivity is affected
by the thermomechanical sensitivity of, and the gap
underneath the MEMS detector as indicated in Equation 5.
The measurement range can be matched for the desired
application through tailoring thermomechanical sensitivity of
the MEMS, which depends on sensor size and layer
thicknesses. Improving the measurement range without
sacrificing from the sensitivity is possible through altering the
sensor gap, which can be achieved through increasing
sacrificial layer thickness. The gap should be adjusted
meanwhile considering plastic deformation. Plastic
deformation was observed after 100 µm displacement, for
millimeter sized parylene based MEMS membranes [24],
implying safe operation for the MEMS sensor, having 5 µm
gap, in this study.
Fig 5c illustrates the response of the MEMS sensor when
actuated with an external laser, chopped at ~ 5 Hz. The
transient response reveals a time constant of 2.5 msec,
allowing the device to acquire data at >100Hz rate. Note that
the data depicted in Fig 5c was acquired with 0.1 msec
intervals (10,000 data points / second), providing 25 data point
per time constant. The variability of acquired signal (standard
deviation / mean) of 20 periods (four of which are shown in
Fig 5c) is calculated to be < 4%. We attribute this deviation
mainly to the laser intensity noise that is present in our laser
diode module. Likewise the external laser used in the response
time experiment, the readout beam (having 30 µW power)
may also cause minor heating on the MEMS membrane,
however, its effect will be stationary.
V. CONCLUSIONS AND DISCUSSION
We demonstrated proof-of-principle testing of the proposed
fiber temperature sensor, via air coupling of the fabricated
MEMS element with the GRIN collimated fiber, and light
detection at the proximal fiber end. The MEMS sensor is
designed in a bimaterial structure. Owing to the thermal
mismatch between its layers with optimized thicknesses, the 1
mm wide MEMS sensor provides a thermomechanical
sensitivity of 833 nm/K. The temperature sensitivity of the
device was measured as 19 mK, which is comparable to offthe shelf fiber temperature sensors [25], [26].
With the integration of the MEMS element on the fiber, we
expect the displacement noise to decrease to a level observed
at the 1st diffraction order, improving the resolution to
δT = 6 mK. The measurements were conducted using a low-
5
cost laser diode source and photodetectors. The temperature
resolution could significantly be improved to sub-mK level
through utilizing a low-noise laser source, or through laser
noise cancellation techniques [27]. The transient response of
the MEMS sensor was acquired experimentally that indicates
a time constant of 2.5 msec, allowing the device to acquire
data at >100Hz rate.
Though the MEMS detector harbors subtle metal parts, the
sputtered metal thickness, volume and mass is only 200-nm, <
1-mm3, and < 2 µg respectively. The paramagnetic property of
titanium ensures that the proposed sensor will not be attracted
by magnetic fields. Besides magnetic attraction, the current
induced due to electromagnetic fields may heat the metal
parts, intervening with the accuracy of measurements.
However, the small diameter (< 1-mm) of the MEMS detector
will significantly limit the temperature that is induced due to
the electromagnetic radiation having greater than centimeterlong wavelength such as that encountered in magnetic
resonance imagers and microwave hyperthermia applications
[22].
Overall, the proposed design offers integration of MEMS
elements manufactured using standard microfabrication
techniques with standard fibers, enabling substitution of the
MEMS sensor (mounted on the ferrule) to alter detection
range and speed.
VI. ACKNOWLEDGMENT
The authors would like to thank Can Erkey from Koç
University for his support in releasing the MEMS sensor and
Semih Sevim for acquiring SEM images. This work was
supported by TUBITAK under grant 114C077.
[1]
[2]
[3]
[4]
[5]
[6]
[7]
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This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/JLT.2015.2502992, Journal of
Lightwave Technology
JOURNAL OF LIGHTWAVE TECHNOLOGY
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H. Ozan Çirkinoğlu received the B.Sc. degree from Istanbul
Technical University in 2015. He is currently a graduate
student at the optoelectronics and photonics engineering, Koç
University, Istanbul. His research interest includes
microphotonics and MEMS.
Habib Bilgin received the B.Sc. degree from Boğaziçi
University in 2013. He is currently running towards his M.Sc
degree at the same institution. His research interest includes
terahertz imaging and MEMS.
Fehmi Çivitci received the M.Sc. degree in the
Microelectromechanical Systems Group at the Middle East
Technical University, Ankara, Turkey, and the Ph.D. degree in
Integrated Optical Micro Systems Group at the University of
Twente, Enschede, the Netherlands. He worked as a
postdoctoral researcher in the Optical Microsystems
Laboratory at Koc University, during 2013-2015. He is now
with the Electronics and Communication Engineering of
Istanbul Technical University. His research interest includes
integrated optics, MEMS and optical coherence tomography.
Hamdi Torun received the B.S. degree from Middle East
Technical University, Ankara, Turkey, in 2003, the M.S.
degree from Koç University, Istanbul, Turkey, in 2005, and
the Ph.D. degree from the Georgia Institute of Technology,
Atlanta, GA, USA, in 2009, all in electrical engineering. He
was a Postdoctoral Fellow with the Department of Mechanical
Engineering, Georgia Institute of Technology, during 2009 to
2010. He is currently an Assistant Professor at the Department
of Electrical and Electronics Engineering and affiliated with
the Center for Life Sciences and Technologies, Bogazici
University, Istanbul. His research interest includes
development of microsystems for biomedical applications.
0733-8724 (c) 2015 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.
This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/JLT.2015.2502992, Journal of
Lightwave Technology
JOURNAL OF LIGHTWAVE TECHNOLOGY
7
Onur Ferhanoğlu received the B.S. and M.S. degrees from
Bilkent University, Ankara, Turkey, in 2003 and 2005,
respectively, in electrical engineering. In 2005, he joined the
Optical Microsystems Laboratory at Koc¸ University as a
Graduate Researcher, where he developed MEMS-based
thermal imaging sensor arrays. During graduate studies, he
visited The Johns Hopkins University in 2004, Georgia Tech.
in 2007, and the Ecole Polytechnique Federale de Lausanne in
2010, as a Research Scholar. After receiving the Ph.D. degree
in 2011, he became a Postdoctoral Fellow at Femtosecond
Laser Assisted Biophotonics Laboratory at the University of
Texas at Austin, Austin, TX, USA, where he played a key role
in the development of an ultrafast laser microsurgery scalpel
from 2011 to 2014. He is currently appointed with the
Electronics and Communications Engineering Department of
Istanbul Technical University, Istanbul, Turkey. His research
interests include biomedical optics and MEMS for medical
applications.
0733-8724 (c) 2015 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.