Dr. Jun Long LIM
Nanyang Technological University, Singapore, Central Singapore, Singapore
Optics | Sensors | Specialty Optical Fiber | Photonics Cryst...
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Academic Career Length
16Years (2011-Present)
(Calculated once Scilit publication data is synced: current year − year of first publication + 1)
Representative Publications
View All Publications7 June 2012 in Optics Letters
Journal Article
DHDora Juan Juan Hu
Dora Juan Juan HuJun Long LIMMJMeng Jiang
Meng Jiang
YWYixin Wang
Yixin Wang
FLFeng Luan
Feng Luan
WTWeijun Tong
Weijun Tong
+2
We propose and demonstrate a novel and simple dual-parameter measurement scheme based on a cascaded optical fiber device of long-period grating (LPG) and photonic crystal fiber (PCF) modal interferometer. The temperature and refractive index (RI) can be measured simultaneously by monitoring the spectral characteristics of the device. The implemented sensor shows distinctive spectral sensitivities of (refractive index unit) and by the LPG, and and by the PCF modal interferometer. The simultaneous measurement of the temperature and external RI is experimentally demonstrated by the sensor. The temperature shift and RI shift calculated by the sensor matrix agree well with the actual temperature and RI change in the experiment.
12 June 2012 in IEEE Photonics Journal
Journal Article
DHDora Juan Juan Hu
Dora Juan Juan HuJun Long LIMYCYing Cui
Ying Cui
KMKarolina Milenko
Karolina MilenkoYWYixin Wang
Yixin Wang
Tomasz Woliński +1
We report on the fabrication and characterization of a highly sensitive temperature sensor by selectively filling the nematic liquid crystal (NLC) 6CHBT into a single void within the photonic crystal fiber (PCF) structure. The temperature response of the device is experimentally characterized, showing good linearity, repeatability, and sensitivity at around -3.90 nm/°C within the temperature range from 44°C to 53°C. The mode properties of the device are theoretically investigated, confirming the mode coupling principle and the temperature sensitivity of the device.
12 April 2012 in Optics Letters
Journal Article
KMKarolina Milenko
Karolina MilenkoDHDora Juan Juan Hu
Dora Juan Juan HuPSPerry Ping SHUM
Perry Ping SHUMTZTaishi Zhang
Taishi Zhang
Jun Long LIMWTWeijun Tong
Weijun Tong
+3
In this paper we present an interferometer based on photonic crystal fiber (PCF) tip ended with a solid silica-sphere for refractive index sensing. The sensor is fabricated by splicing one end of the holey PCF to a single mode fiber (SMF) and applying arc at the other end to form a solid sphere. The sensor has been experimentally tested for refractive index and temperature sensing by monitoring its wavelength shift. Measurement results show that the sensor has the resolution of the order of over the refractive index range of 1.33–1.40, and temperature sensitivity of the order of in the range of 20–100 °C.
23 September 2011 in IEEE Sensors Journal
Journal Article
DHDora Juan Juan Hu
Dora Juan Juan HuYWYixin Wang
Yixin Wang
Jun Long LIMTZTaishi Zhang
Taishi Zhang
KMKarolina Milenko
Karolina MilenkoTomasz Woliński +8
In this paper, we report and demonstrate a novel miniaturized intrinsic Fabry-Perot interferometer (IFPI) based on a simplified hollow core fiber ended with a hollow silica sphere tip. The hollow core fiber is spliced to single mode fiber and subsequently applied with fusion arc at the end, forming a hollow sphere with a thin silica wall. The reflection spectrum is modulated by the environment of the sensor head such as refractive index and temperature. By monitoring and measuring the fringe visibility, the measurement of refractive index of the calibrated solution is carried out experimentally. The achievable refractive index (RI) resolution is about 6.2 × 10-5 by measuring the fringe visibility. This sensor offers key features and advantages of IFPI including easy fabrication, low loss, low cost, and good fringe visibility. Furthermore, the sensor head is made of single material and therefore has the potential for measurements in harsh environments. Measurements at high temperatures up to ~ 1000°C are carried out. Results reveal that the sensor has low temperature.
9 October 2012 in IEEE Photonics Journal
Journal Article
DHDora Juan Juan Hu
Dora Juan Juan HuPSPerry Ping SHUM
Perry Ping SHUMJun Long LIMYCY. Cui
Y. Cui
KMKarolina Milenko
Karolina MilenkoTomasz Woliński +1
A directional coupler structure formed by a nematic liquid crystal (NLC)-filled photonic crystal fiber (PCF) represents a promising configuration in sensing applications. Because of large refractive index difference between the NLC and silica material, the mode coupling between the NLC waveguide and the silica core is more complicated than the situation of coupling between two fundamental modes of the waveguides. Therefore, it is necessary to perform a theoretical investigation of the mode properties associated with the experimental studies of the coupling characteristics. In this paper, we present a thorough analysis, both theoretically and experimentally, of the directional coupler structure, including the mode properties, coupling characteristics, and thermal sensing properties. The temperature response of the device is experimentally measured, showing a polynomial curve in nematic phase and a linear curve in isotropic phase. The nonlinearity of the temperature response of the device in nematic phase and the linearity in isotropic phase are attributed to the temperature dependence of the refractive index of the NLC. Specifically, the sensitivity is -3.86 nm/°C in isotropic phase of the 6CHBT with good linearity and shows good agreement with simulation results.
26 September 2011 in IEEE Journal of Selected Topics in Quantum Electronics
Journal Article
DHDora Juan Juan Hu
Dora Juan Juan HuJun Long LIMMPMi Kyoung Park
Mi Kyoung Park
LKLinus Tzu-Hsiang Kao
Linus Tzu-Hsiang Kao
YWYixin Wang
Yixin Wang
WTWeijun Tong
Weijun Tong
+1
We report the fabrication of a highly sensitive refractometer based on photonic crystal fiber (PCF) interferometry. Using fusion arc splicing technique, a short length of PCF (∼3 mm) was spliced to conventional single-mode fibers on both sides. The voids of the PCF were completely collapsed in the splice region, which acted as mode splitter and combiner on both sides. Microbubbles were formed in the splice region and acted as diverging lens for exciting cladding modes efficiently. The transmission spectrum exhibited detectable “dips” for refractive index (RI) sensing. The bulk liquid sensitivity can reach up to 320 nm/RIU (RI unit) based on the linear curve fit for RI ranging from 1.33 to 1.34. Biosensing experiment was carried out using streptavidin and biotin as respective analyte and receptor. To the best of authors’ knowledge, this is the first time of reporting bioaffinity test on the external surface of PCF using modal interferometry.
About Me
Jun Long LIM received the B.Eng. (Hons.) and Ph.D degree in electrical and electronic engineering from Nanyang Technological University, Singapore, in 2010 and 2018 respectively.
Between 2010 to 2024, he had been with the Agency for Science, Technology and Research (A*STAR), Singapore, where he was a research engineer, became a senior research engineer in 2016, and changed track (emplacement) to a scientist in 2019. He held key research appointments with A*STAR’s I2R as deputy lab head and strategic planning manager from 2014 to 2016, and principal investigator from 2019 to 2023. He holds four patents, has published more than 25 international scientific papers and has editorial roles at Photonics. His current research interests include Photonic Crystal Fiber (PCF), harsh environment sensor, numerical simulation, interferometry, and fiber refractometry.
Dr. Lim is the recipient of the A*STAR Scientific Staff Development Award in 2015, the SMP Outstanding Mentor Award in 2016, and the A*STAR Champion Award in 2021, 2022, 2023. He was also the co-recipient of the ASEAN Outstanding Engineering Achievement Award and the IES Prestigious Engineering Achievement Award in recognition of his outstanding research work in the area of Fiber Bragg Grating (FBG) sensors for security fence in 2013. #limjunlong #limexploration
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