Showing papers by "Jinhui Yuan published in 2020"

Ultrahigh-sensitivity label-free optical fiber biosensor based on a tapered singlemode- no core-singlemode coupler for Staphylococcus aureus detection

Abstract: An ultra-high sensitivity label-free optical fiber biosensor for inactivated Staphylococcus aureus (S. aureus) detection is proposed and investigated in this study, with additional advantages of robust and stability compared to traditional tapered fiber structure. The proposed fiber biosensor is based on a tapered singlemode- no core-singlemode fiber coupler (SNSFC) structure, where the no core fiber was tapered to small diameter (taper-waist diameter of about 10 μm) and functionalized with the pig immunoglobulin G (IgG) antibody for detection of S. aureus. The measured maximum wavelength shift of the sensor for an S. aureus concentration of 7 × 101 CFU/mL (colony forming unit per milliliter) is 2.04 nm, which is equivalent to a limit of detection (LOD) of 3.1 CFU/mL (a highest LOD reported so far for optical fiber biosensors), considering the maximum wavelength variation of the sensor in phosphate buffered saline (PBS) is ±0.03 nm over 40 min, where 3 times of maximum wavelength variation (3 × 0.03 = 0.09 nm) is defined as measurement limit. The response time of the developed fiber sensor is less than 30 min. The ultra-sensitive biosensor has potential to be widely applied to various areas such as disease, medical diagnostics and food safety inspection.

Hollow-Core Negative Curvature Fiber with High Birefringence for Low Refractive Index Sensing Based on Surface Plasmon Resonance Effect

Abstract: In this paper, a hollow-core negative curvature fiber (HC-NCF) with high birefringence is proposed for low refractive index (RI) sensing based on surface plasmon resonance effect. In the design, the cladding region of the HC-NCF is composed of only one ring of eight silica tubes, and two of them are selectively filled with the gold wires. The influences of the gold wires-filled HC-NCF structure parameters on the propagation characteristic are investigated by the finite element method. Moreover, the sensing performances in the low RI range of 1.20-1.34 are evaluated by the traditional confinement loss method and novel birefringence analysis method, respectively. The simulation results show that for the confinement loss method, the obtained maximum sensitivity, resolution, and figure of merit of the gold wires-filled HC-NCF-based sensor are -5700 nm/RIU, 2.63 × 10-5 RIU, and 317 RIU-1, respectively. For the birefringence analysis method, the obtained maximum sensitivity, resolution, and birefringence of the gold wires-filled HC-NCF-based sensor are -6100 nm/RIU, 2.56 × 10-5 RIU, and 1.72 × 10-3, respectively. It is believed that the proposed gold wires-filled HC-NCF-based low RI sensor has important applications in the fields of biochemistry and medicine.

Surface plasmon resonance-based silicon dual-core photonic crystal fiber polarization beam splitter at the mid-infrared spectral region

Abstract: In this paper, a novel silicon dual-core photonic crystal fiber (Si-DC-PCF) polarization beam splitter (PBS) based on the surface plasmon resonance effect is proposed The mode-coupling characteristics between the X- and Y-polarized even and odd modes and surface plasmon polariton mode are analyzed by using the finite-element method and coupled-mode theory The influences of the structure parameters of the Si-DC-PCF on the coupling length and coupling length ratio are investigated The normalized output power of the X- and Y-polarized modes in cores A and B and the corresponding extinction ratio are also discussed By optimizing the structure parameters of the Si-DC-PCF, the PBS length of 192 µm and bandwidth of 830 and 730 nm in cores A and B are achieved It is believed that the proposed Si-DC-PCF PBS can find important applications in mid-infrared laser and sensing systems

Novel Microfiber Sensor and Its Biosensing Application for Detection of hCG Based on a Singlemode-Tapered Hollow Core-Singlemode Fiber Structure

Abstract: A novel microfiber sensor is proposed and demonstrated based on a singlemode-tapered hollow core-singlemode (STHS) fiber structure. Experimentally a STHS with taper waist diameter of $26.5~\mu \text{m}$ has been fabricated and RI sensitivity of 816, 1601.86, and 4775.5 nm/RIU has been achieved with RI ranges from 1.3335 to 1.3395, from 1.369 to 1.378, and from 1.409 to 1.4175 respectively, which agrees very well with simulated RI sensitivity of 885, 1517, and 4540 nm/RIU at RI ranges from 1.3335 to 1.337, from 1.37 to 1.374, and from 1.41 to 1.414. The taper waist diameter has impact on both temperature and strain sensitivity of the sensor structure: (1) the smaller the waist diameter, the higher the temperature sensitivity, and experimentally 26.82 pm/°C has been achieved with a taper waist diameter of $21.4~\mu \text{m}$ ; (2) as waist diameter decrease, strain sensitivity increase and 7.62 pm/ $\mu \varepsilon $ has been achieved with a taper waist diameter of $20.3~\mu \text{m}$ . The developed sensor was then functionalized for human chorionic gonadotropin (hCG) detection as an example for biosensing application. Experimentally for hCG concentration of 5 mIU/ml, the sensor has 0.5 nm wavelength shift, equivalent to limit of detection (LOD) of 0.6 mIU/ml by defining 3 times of the wavelength variation (0.06 nm) as measurement limit. The biosensor demonstrated relatively good reproducibility and specificity, which has potential for real medical diagnostics and other applications.

Sensing Characteristics of Fiber Fabry-Perot Sensors Based on Polymer Materials

Abstract: A simple optic-fiber Fabry-Perot (FP) sensing technique was proposed and experimentally investigated by using polymer material to connect the ends of two singlemode fibers. Four different polymer materials (benzocyclobutene (BCB), UV88 (Relentless, China), Loctite3525 (HenKel, Germany), and NOA68 (Norland, USA)) filling the FP cavity were used to comparatively study the sensing performance of temperature, strain and refractive index. The result shows that the FP sensor with BCB has excellent repeatability with good linear response to temperature in a wide range from room temperature to 250 °C, which is much larger than that of other three materials (<; 90 °C), while UV88 with a cost of less than 1/10 of the other three polymer materials has the best sensitivity to strain and temperature. In addition, the FP sensor was firstly applied to measure ultraviolet (UV) light intensity. The test results demonstrate that the proposed FP sensor structure has a good linear response and repeatability to UV intensity for all four polymer materials, and Loctite3525 has the highest sensitivity (0.0087 nm/(mw/cm 2 )) and the best repeatability among the four polymer materials.

Dispersion-Engineered T-type Germanium Waveguide for Mid-Infrared Supercontinuum and Frequency Comb Generations in All-Normal Dispersion Region

Abstract: In this paper, a T-type germanium (Ge) waveguide with an all-normal dispersion profile is designed for mid-infrared (MIR) supercontinuum (SC) and frequency comb generations. The nonlinearity coefficient of the designed waveguide is calculated as 30.48 W-1·m-1 at the initial pump wavelength of 3.0 µm. Moreover, the group-velocity dispersion is kept low and flat in the considered wavelength range. Simulation results show that with the designed waveguide, the highly coherent and octave-spanning MIR SC can be generated in the wavelength range from 1.85 to 9.98 µm (more than 2.4 octaves) when the pump pulse with wavelength of 3.0 µm, peak power of 900 W, and duration of 120 fs is launched into the 5 mm long waveguide. When the pulse train including 50 pulses at a repetition rate of 100 MHz is used as the pump source, the SC-based frequency comb is obtained.

Theoretical and numerical analyses for PDM-IM signals using Stokes vector receivers

Abstract: Different from current coherent-detection-based long-haul transmission systems, inter- and intradatacenter transmissions require a simpler transmitter and receiver. A promising way to significantly meet the demands of datacenter transmission is polarization division multiplexing intensity modulation with direct detection (PDM-IM-DD) using a Stokes vector receiver (SVR). However, for different SVR architectures, the corresponding demultiplexing matrix is required to recover the Stokes vectors from the detected signals, which are combined with an arbitrary state of polarization (SOP), will change the effect of noise dynamically and significantly influence the system performance. In this study, PDM-IM signals using four SVRs, i.e., a 90° optical hybrid with 2 balanced photodetectors (BPDs) and 2 photodetectors (PDs), a 90° optical hybrid with 4 PDs, a Stokes analyzer and a 3 × 3 coupler with 4 PDs, are studied theoretically and numerically. Theoretical system models using the four SVRs are developed, and the noise power variations are analyzed quantitatively based on these models. Moreover, the performance of the systems is also investigated for 224 Gbit/s polarization division multiplexing pulse amplitude modulation 4 level with direct detection (PDM-PAM4-DD) transmission in a simulation. The simulation results show that the bit error rate (BER) performance of the systems is consistent with the theoretical noise power variation curves. The theoretical analysis scheme is helpful for the practical design of SVR-based systems.

Liquid Crystal-Filled Dual-Core Photonic Crystal Fiber Single-Polarization Wavelength Splitter

Abstract: A nematic liquid crystal-filled dual-core photonic crystal fiber single-polarization wavelength splitter is proposed. The length of the splitter is 2.38 mm, and the crosstalk between the wavelengths 1.31 and 1.55 μm can achieve -68.18 dB.

Design of Photonic Crystal Fiber Refractive Index Sensor Based on Surface Plasmon Resonance Effect for the Dual-Wavebands Measurement

Abstract: In this paper, we propose a photonic crystal fiber (PCF) refractive index (RI) sensor based on the surface plasmon resonance (SPR) effect. The coupling and sensing characteristics of the proposed P...

Graphene-Coated Two-Layer Dielectric Loaded Surface Plasmon Polariton Rib Waveguide With Ultra-Long Propagation Length and Ultra-High Electro-Optic Wavelength Tuning

Abstract: A graphene-coated two-layer dielectric loaded surface plasmon polariton (GTDLSPP) rib waveguide is designed. The mode characteristics and electro-optic (EO) modulation performances of the four hybrid plasmonic modes (HPMs) in the designed waveguide are simulated by using the finite element method. The simulation results show that a 10 3 mm-scale propagation length and an effective mode field area of ~λ 2 /1333 are obtained by adjusting the bias voltage. The EO wavelength tunings are -68.6, -42.0, -49.7, and -11.1 nm/V for the HPM 1, HPM 2, HPM 3, and the peak 2 of HPM 4, which are two orders of magnitude larger than those of other EO modulation structures. For the peak 1 of the HPM 4, the EO wavelength tuning is the piecewise linear. For a 150-μm long waveguide, the modulation depths of ~98.7, ~87.9, and 99.5%, and FWHMs of ~450, ~100, and ~42 nm can be achieved for the HPM 1, HPM 2, and HPM 3. For the HPM 4, there are two peaks in the transmission spectrum. The modulation depths are ~97.3 and 75.2%, and FWHMs are ~92 and ~34 nm for the peaks 1 and 2. There is a tradeoff between the modulation depth and FWHM for different waveguide lengths. The GTDLSPP rib waveguide designed has small size, high modulation depth, broad bandwidth, and compatibility with the CMOS technology, soit has potential applications in the EO tunable devices, optical interconnects, and optical switches.

Passive Generation of the Multi-Wavelength Parabolic Pulses in Tapered Silicon Nanowires

Abstract: In this paper, passive generation of the multi-wavelength parabolic pulses (PPs) in tapered silicon nanowires (TSNs) is numerically investigated. The coupled inhomogeneous nonlinear Schrodinger equation (INLSE) is derived in the context of TSN to model the multi-wavelength PP generation. The TSN is designed based on the well-known self-similar theory that the group-velocity dispersion is decreased while the nonlinear coefficient is unchanged along the propagative direction. While the pump wavelengths for three input pulses are specially set with equal intervals of 18, 12, and 6 nm, the time-domain profiles are aligned at the same position. Simulation results show that except for wavelength interval, the waveguide length is also a critical factor that influences the quality of generated PP. Both of them reshape the pulse profile by the means of walk-off effect which depends on the cross-phase modulation between multiple pulses. By properly optimizing the input parameters of Gaussian pulses as well as the center wavelength interval and TSN length, we prove that the generation of two- even three-wavelength PPs with high-quality is feasible.

Mid-Infrared Supercontinuum and Frequency Comb Generations by Different Optical Modes in a Multimode Chalcogenide Strip Waveguide

Abstract: Supercontinuum (SC) with broad bandwidth and high coherence is crucial in the SC-based frequency comb source generation. In this paper, we numerically investigate the mid-infrared (MIR) SC generations with the three optical modes (TE00, TE10, and TE20) in a multimode chalcogenide (As2Se3) strip waveguide. The waveguide structure is carefully engineered to ensure that the pump pulses are propagated in the normal dispersion regions of the considered three optical modes. Highly coherent and octave-spanning MIR SCs are generated when the optimized pump pulse with 80-fs pulse duration, 3-kW peak power, and 3- $\mu \text{m}$ center wavelength is used. Moreover, the nonlinear dynamics of the SC generation are numerically analyzed. Finally, the SC-based frequency combs are numerically demonstrated when a pulse train with a repetition rate of 50 MHz is used as the pump source and launched into the multimode As2Se3-based strip waveguide. It is believed that the generated MIR SC and SC-based frequency comb sources have important applications in biophotonics, metrology, and sensing.

The Pre-configured Kramers-Kronig Scheme

Abstract: A pre-configured Kramers-Kronig (Pre-KK) scheme is proposed for single sideband (SSB) systems and demonstrated that a better performance can be achieved than traditional KK scheme because of reducing the requirement of DAC and ADC resolution.

Boardband Coherent Comb Generation in an All-Normal-Dispersion AlGaAs-on-Sapphire Waveguide

Abstract: We experimentally demonstrate coherent comb generation in a 5-mm long all-normal-dispersion AlGaAs-on-sapphire waveguide with a 47% pump-to-comb conversion efficiency. We achieve a 20-dB bandwidth of 24.5 THz covering from the S- to U-band wavelength ranges.

Dual-Core Photonic Crystal Fiber Polarization Beam Splitter Based on Surface Plasmon Resonance Effect

Abstract: We design a dual-core photonic crystal fiber (PCF) polarization beam splitter (PBS) based on surface plasmons resonance effect. The maximum extinction ratio of the PBS can be up to -160.56 dB at wavelength 1.55 μm.

Nonlinear correction of frequency-modulated continuous-wave lidar frequency modulation based on singular value decomposition-least square algorithm

Abstract: Frequency-modulated continuous-wave (FMCW) lidars combine the advantages of lasers and FMCW radars and have a wide range of applications in three-dimensional imaging and meteorological observation. However, its spatial resolution is directly limited by the nonlinearity of laser frequency sweep. A nonlinear correction method is proposed using a singular value decomposition (SVD)-least squares algorithm, which can calculate the nonlinear coefficient of each order accurately by minimizing the error between the actual phase and the fitted phase. In the simulation, the results demonstrate that the proposed method can achieve significantly better performance on nonlinearity and root-mean-square error (RMSE) than that of the conventional high-order ambiguity function (HAF) algorithm. Calculation results show that, for the SVD algorithm, the nonlinearity and RMSE are reduced by 50.37% and 52.55%, respectively, compared with those of the HAF algorithm under the signal-to-noise ratio of 25 dB, proving the performance improvement of the proposed algorithm.

Refractive index sensor based on multimode interference in a twin-hole fiber

Abstract: We report a simple refractive index (RI) sensor based on a twin-hole fiber (THF). The THF is fused with the single-mode fiber to realize sensing by the multimode interference. The mode transmission characteristics in the THF are numerically investigated. In the sensing experiment, when the surrounding RI changes, the wavelength shift of the transmission spectrum shows approximate linearity in the low RI region and nonlinearity in the high RI region. When a THF with the length of 10 mm is used, the highest sensitivity can be up to 1351 nm / RIU in the RI range from 1.430 to 1.445. Moreover, the effect of the temperature on the transmission spectrum relative to the RI is much smaller when the external temperature changes from 30°C to 80°C.

Directional bend sensing based on high birefringence dual-core photonic crystal fiber

Abstract: We propose and demonstrate a directional bend sensing based on Mach-Zehnder interferometer in a high birefringence dual-core photonic crystal fiber. Its curvature sensitivity is up to 4.24 nm/m-1 within the curvature range of 2.19-3.99 m-1. © 2019 The Author(s)

Multi-view 3D light field video broadcast system

Abstract: Large viewing angle, dense viewpoints, high-resolution 3D light field display technology can achieve large viewing angle, high resolution, and high dynamic reconstruction of the objective world scene light field, which is an important direction for the development of future display technology. The application of advanced 3D light field display technology is getting more and more attention. However, the current lack of efficient access to large viewing angles, dense viewpoints, and high-resolution 3D light field content limits its development and application. To this end, here proposes a dense viewpoints video generation, coding, transmission method, and build a super multi-view 3D light field video live broadcast system. The method and system are composed of 3D light field video generation, light field video coding, light field video transmission and a display part. It can provide viewers with a real-time, high-quality 3D visual experience.

Ultra-Broadband Silicon Dual-Core Photonic Crystal Fiber Polarization Beam Splitter at Mid-Infrared Spectral Region Based on Surface Plasmon Resonance

Abstract: An ultra-broadband silicon dual-core photonic crystal fiber polarization beam splitter at mid-infrared spectral region based on surface plasmon resonance is proposed. The bandwidths of the cores A and B are 730 and 580 nm, respectively.

A tunable-order all-optical temporal differentiator based on phase-shifted Bragg gratings

Abstract: A method for adjusting the differential order of a silicon-based waveguide grating differentiator by inputting light, which is through two-photon absorption and free carrier absorption effects, is proposed. The simulation results are demonstrated.