Dr. Dora J. Hu Profile

Dr. Dora J. Hu

Research Engineer at Institute for Infocomm Research

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Publications (8)

Proceedings Article | 10 April 2020 Presentation + Paper

Temperature sensor based on selective liquid-filled twin-core photonic crystal fiber

Chenlu Wang, Perry Ping Shum, Dora Juan Juan Hu, Zhilin Xu, Shuhui Liu, Yongwei Zhu, Yu Zheng, Baocheng Li, Yang Chen, Weijun Tong, Yue Meng, Georges Humbert

Proceedings Volume 11354, 113542U (2020) https://doi.org/10.1117/12.2556997

KEYWORDS: Temperature sensors, Photonic crystal fibers, Optofluidics

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We experimentally demonstrated a temperature sensor by selectively infiltrating refractive index liquid (RIL) in the central air hole of a twin-core photonic crystal fiber (PCF). The selective liquid infiltration was realized by putting the PCF in the bulk liquid with its central air hole open for liquid infiltration using capillary effect. The rest of the air holes were covered by UV glue. The three-dimensional stage was used to translate the PCF, and a tapered SMF was used to transfer the UV glue to cover the air holes under the microscope. After UV glue was solidified by exposing the fiber end under the UV light, the PCF end was dipped into the RIL to fill the central air hole by capillary effect. Due to the large thermos-optic coefficient of the RIL, the RIL filled air channel would act as a liquid core whose core modes would be highly dependent on the ambient temperature. The core modes of the RIL filled core would be phase matched to the fundamental mode of the two solid cores. Therefore, the phase matching wavelengths for the mode coupling among the two solid cores of PCF and the liquid core were highly temperature sensitive. The resonant dips in the transmission spectrum were measured to estimate the temperature sensitivity. The experiment used a commercially available twin core PCF, and blocked all but the central airhole at one of the ends facets by UV glue (NOA81, Norland), the remaining open holes are infiltrated over a length of 10 cm by capillary force with fluid (Cargille Laboratories Inc. index-matching fluid, series A) that possesses a refractive index of 1.46 at 589.3nm, 25°C, and the thermal coefficient is – 0.000389 RIU/°C, which is around 10 times of that coefficient of silica. Any temperature induced changes will have an influence on the propagation properties because of the highly temperature response of the refractive index of the fluid. With a fiber cleaver, a 1.8 cm long PCF was then cut from the longer length of the partially liquid filled twin core PCF and then fusion spliced with SMFs at both ends to observe its transmission spectrum when the sample is heated. When the temperature increase to around 54°C, the liquid RI drops quickly to match that of silica, and a three parallel waveguide structure is formed, in which the central liquid waveguide have the same index value with the two solid core. Because of the small separation between adjacent waveguides, a strong mode-field overlap occurs, which leads to a significant enhancement of the coupling coefficient, therefore, light energy can be easily transferred between two solid cores and the liquid rod in a short coupling length. Thus, the transmission spectrum of the device contain two sets of interference fringe pattern, the large spectrum envelope originated from the interference between the three eigenmodes generated by three-parallel waveguide structure based on the mode coupling theory, and fine interference fringes generated by the interference between the higher order modes in one core. By tracking the dip wavelength shift of the large spectrum envelope, the sensor exhibited a high temperature sensitivity of up to 37.011 nm/°C within the temperature range from 53.8°C to 55°C due to the satisfaction of phase match condition, and maintain a high sensitivity of 19.681 nm/°C from 55°C to 58.2°C, which is benefit from the high thermal optic coefficient of the selectively filled liquid in the twin core PCF.

Proceedings Article | 27 February 2015 Paper

Fiber-integrated second harmonic generation modules for visible and near-visible picosecond pulse generation

Thomas Legg, Andrew Robertson, Robert Eckardt, Timothy Runcorn, Dora Hu, Robert Murray, Edmund Kelleher, Sergei Popov, James Taylor

Proceedings Volume 9347, 93470B (2015) https://doi.org/10.1117/12.2078726

KEYWORDS: Second-harmonic generation, Picosecond phenomena, Crystals, Fiber lasers, Raman spectroscopy, Harmonic generation, Fiber amplifiers, Visible radiation, Stimulated emission depletion microscopy, Laser sources

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Proceedings Article | 11 November 2008 Paper

Hole-assisted lightguide fiber for dispersion tailoring

Dora Juan Hu, Ping Shum, Chao Lu, Huai Yu Meng

Proceedings Volume 7134, 71343F (2008) https://doi.org/10.1117/12.803352

KEYWORDS: Dispersion, Refractive index, Cladding, Waveguides, Solids, Structured optical fibers, Optical fibers, Optical properties, Silica, Polymers

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Proceedings Article | 4 December 2007 Paper

All-optical microwave photonic filters with Hi-Bi linearly chirped grating

Yandong Gong, YongXin Guo, O. L. C. Michael, G. X. Ning, Juanjuan Hu, Ping Shum, H. Dong, M. Tang, S. N. Fu, G. B. Ren, Lam Quoc Huy

Proceedings Volume 6781, 67813F (2007) https://doi.org/10.1117/12.738710

KEYWORDS: Linear filtering, Microwave radiation, Radio over Fiber, Microwave photonic filters, Optical filters, Bandpass filters, Single mode fibers, Polarization, Coherence (optics), Phase modulation

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Proceedings Article | 21 November 2007 Paper

Full-vectorial analysis of photonic crystal fibers using a compact two-dimensional finite-difference time-domain method

Juan Juan Hu, Ping Shum, Chao Lu, Guobin Ren

Proceedings Volume 6781, 67811J (2007) https://doi.org/10.1117/12.745218

KEYWORDS: Finite-difference time-domain method, Photonic crystal fibers, Silica, Dispersion, Magnetism, Polarization, Differential equations, Refractive index, Analytical research, Modal analysis

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Proceedings Article | 21 November 2007 Paper

Investigation on optimized launch power in the distributed Brillouin fiber sensor design

Y. D. Gong, Yongxin Guo, Ping Shum, Juanjuan Hu, H. Dong, S. N. Fu, M. Tang, X. L. Tian, Q. H. Lam, J. Z. Hao, O. L. C. Michael, J. H. Ng, V. Paulose

Proceedings Volume 6781, 67812I (2007) https://doi.org/10.1117/12.741242

KEYWORDS: Sensors, Signal to noise ratio, Fiber lasers, Fiber optics sensors, Optical fibers, Scattering, Temperature metrology, Modulators, Fiber Bragg gratings, Reflectometry

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Proceedings Article | 21 November 2007 Paper

Experimental investigation of tunable all-solid photonic bandgap fiber coupler

Guobin Ren, Ping Shum, JuanJuan Hu, Xia Yu

Proceedings Volume 6781, 678112 (2007) https://doi.org/10.1117/12.743478

KEYWORDS: Polishing, Fiber couplers, Micro optical fluidics, Cladding, Photomicroscopy, Silica, Fabrication, Surface finishing, Structured optical fibers, Single mode fibers

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Proceedings Article | 18 October 2006 Paper

Flexible bandwidth control of the single-mode guided band in a 2D photonic crystal coupled-cavity waveguide

Juan Juan Hu, Xiyao Chen, Ping Shum, Xia Yu, Chao Lu

Proceedings Volume 6369, 63690I (2006) https://doi.org/10.1117/12.684869

KEYWORDS: Waveguides, Photonic crystals, Dielectrics, Control systems, Single mode fibers, Dispersion, Multiplexers, Demultiplexers, Structural design, Optical design

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Showing 5 of 8 publications

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