Changyuan Yu

Changyuan Yu
National University of Singapore | NUS · Department of Electrical & Computer Engineering

PhD

About

322
Publications
16,080
Reads
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3,208
Citations
Additional affiliations
January 2010 - present
The Hong Kong Polytechnic University
January 2010 - present
December 2005 - present
National University of Singapore
Education
August 2000 - August 2005
University of Southern California
Field of study
  • Electrical Engineering
August 1997 - June 1999
University of Miami
Field of study
  • Electrical & Computer Engineering
September 1992 - July 1997
Tsinghua University
Field of study
  • Applied Physics and Enterprise Management

Publications

Publications (322)
Article
Ballistocardiography (BCG) is a vibration signal related to cardiac activity, which can be obtained in a non-invasive way by optical fiber sensors. In this paper, we propose a modified generative adversarial network (GAN) to reconstruct BCG signals by solving signal fading problems in a Mach-Zehnder interferometer (MZI). Based on this algorithm, ad...
Article
Light emitting diodes (LED) is a promising device in visible light communication (VLC), enabling simultaneous illumination and data transmission via visible light. However, the generation of modulated visible light signals causes variation to the LED intensity in intensity modulation/direct detection (IM/DD) transmission, which may cause flickering...
Article
Full-text available
Recently, ultrathin metalenses have attracted dramatically growing interest in optical imaging systems due to the flexible control of light at the nanoscale. In this paper, we propose a dual-wavelength achromatic metalens that will generate one or two foci according to the polarization of the incident. Based on geometric phase modulation, two unit...
Article
The advent of metasurface technology has revolutionized the field of optics and photonics in recent years due to its capability of engineering optical wavefronts with well-patterned nanostructures at subwavelength scale. Meanwhile, inspired and benefited from the tremendous success of the "lab-on-fiber" concept, the integration of metasurface with...
Article
Full-text available
With the widespread use of few-mode fibers, mode characteristics testing becomes essential. In this paper, current few-mode fiber testing techniques are discussed, and the S2 imaging technique is chosen and demonstrated to be capable of few-mode fiber characterization in principle. As a result, the few-mode fiber characterization system with the S2...
Article
Full-text available
A novel optical performance monitoring (OPM) method based on Fourier transform spectrum analysis (FTSA) is designed for optical signal-to-noise ratio (OSNR) monitoring, modulation format and baud rate recognition in the presence of fiber nonlinearities. The interference intensities, which reflect spectral features of signals, are obtained by exploi...
Article
Full-text available
Due to the improvement of living standards, people’s attention to health has gradually increased. More and more people are willing to spend money and time on health management. This article reviews work on the vital signs monitoring system based on fiber optic interferometers, including the design of sensor structures, signal demodulation methods a...
Article
We propose the asynchronous control of anisotropic diffusion (AD) algorithm, and such asynchronous anisotropic diffusion (AAD) algorithm is demonstrated experimentally to reduce noise from the sensing signals obtained from Brillouin distributed optical fiber sensors. The performance of the proposed AAD algorithm is analyzed in detail for different...
Preprint
div>We experimentally demonstrate a C band 100Gbit/s intensity modulation and direct detection entropy-loaded multi-rate Nyquist-subcarrier modulation signal over 100km dispersion-uncompensated link. A record capacity-reach of 10Tbit/s×km is achieved.</div
Preprint
Full-text available
div>We experimentally demonstrate a C band 100Gbit/s intensity modulation and direct detection entropy-loaded multi-rate Nyquist-subcarrier modulation signal over 100km dispersion-uncompensated link. A record capacity-reach of 10Tbit/s×km is achieved.</div
Article
An optimized design of 7-ring-core 5-mode-group fiber for mode-group-based dense space-division multiplexing (DSDM) is proposed. It is found that decreasing the refractive index of the center and trench of each ring core can increase the available ring-core thickness and meanwhile suppress the radial higher-order modes. Based on the simulation, a f...
Article
Full-text available
To increase the transmission capacity, ultra-wideband wavelength-division multiplexing (UWB WDM) has been exploited to enlarge the spectral range. However, inter-channel stimulated Raman scattering (ISRS) results in power transition from high-frequency channels to low-frequency channels in wideband scenarios, which degrades the Q-factor of signals....
Article
In this paper, to the best of our knowledge, we propose the first multi-rate Nyquist-subcarriers modulation (SCM) for C-band 100Gbit/s signal transmission over 50km dispersion-uncompensated link. Chromatic dispersion (CD) introduces severe spectral nulls on optical double-sideband signal, which greatly degrades the performance of intensity-modulati...
Article
Full-text available
In this paper, the hollow core Bragg fiber (HCBF)-based sensor based on anti-resonant reflecting optical waveguide (ARROW) model is proposed and experimentally demonstrated for simultaneous measurement of curvature and temperature by simply sandwiching a segment of HCBF within two single-mode fibers (SMFs). The special construction of a four-bilaye...
Article
A modified solid fiber-optic integrated Mach-Zehnder interferometer (IMZI) assisted with a thin piezoelectric sheet (TPS, ~ 130um thickness) and phase generated carrier (PGC) demodulation is proposed and investigated theoretically and experimentally. The IMZI’s two arms are respectively molded with epoxy resin (EP) and silicone rubber (SI). These t...
Article
Applications of machine learning (ML) models in optical communications and networks have been extensively investigated. For an optical wavelength-division-multiplexing (WDM) system, the quality of transmission (QoT) estimation generally depends on many parameters including the number and arrangement of WDM channels; launch power of each channel; nu...
Article
In this paper, the theoretical bit error rate (BER) of N-level pulse amplitude modulation (PAM-N) and M-ary quadrature amplitude modulation (M-QAM) have been studied and compared under different scenarios, including (i) PAM with intensity modulation with direct detection (IM/DD) and field modulation with detection (FMD) (including coherent detectio...
Preprint
Full-text available
In this paper, to the best of our knowledge, we propose the first multi-rate Nyquist-subcarriers modulation (SCM) for C-band 100Gbit/s signal transmission over 50km dispersion-uncompensated link. Chromatic dispersion (CD) introduces severe spectral nulls on optical double-sideband signal, which greatly degrades the performance of intensity-modulati...
Article
A solid unobtrusive fiber-optic sensor based on modal interference in dual mode fiber (DMF) embedded in a thin mat is proposed and investigated theoretically and experimentally, realizing real-time vital signs and activity monitoring. The whole sensing setup only consists of one laser diode, one section of DMF, one photo-detector and few standard s...
Article
We discuss the mode properties for orbital angular momentum (OAM) modes supporting multi-mode ring-core fiber (MM-RCF). For strongly-guiding MM-RCF, by introducing one more layer to the ring-core, a two-layer ring-core fiber (TL-RCF) is proposed. It is proven that this TL-RCF can increase the separation degree between the vector eigenmodes and mean...
Article
Full-text available
The orbital angular momentum (OAM) of light provides a new degree of freedom for carrying information. The stable propagation and generation of OAM modes are necessary for the fields of OAM-based optical communications and microscopies. In this review, we focus on discussing the novel fibers that are suitable for stable OAM mode transmission and co...
Article
Cardiovascular diseases (CVDs) are very common in modern society, such as atherosclerosis, hypertension, etc., which have a great impact on heart function. Therefore, hospitalization monitoring alone is far from enough. Long-term monitoring of the heart is needed in daily life. The technology of non-invasive monitoring of the cardiovascular system...
Article
In this paper, we present a field-trial C-band 72Gbit/s optical on-off keying (OOK) system over 18.8 km dispersion-uncompensated submarine optical cable in the South China Sea. Chromatic dispersion (CD) of 18.8 km submarine optical cable causes four spectral nulls on the 36 GHz bandwidth of 72Gbit/s OOK signal, which is the main obstacle for achiev...
Preprint
Full-text available
In this paper, we present a field-trial C-band 72Gbit/s optical on-off keying (OOK) system over 18.8km dispersion-uncompensated submarine optical cable in the South China Sea. Chromatic dispersion (CD) of 18.8km submarine optical cable causes four spectral nulls on the 36GHz bandwidth of 72Gbit/s OOK signal, which is the main obstacle for achieving...
Article
Full-text available
Red palm weevil (RPW) is a detrimental pest, which has wiped out many palm tree farms worldwide. Early detection of RPW is challenging, especially in large-scale farms. Here, we introduce the combination of machine learning and fiber optic distributed acoustic sensing (DAS) techniques as a solution for the early detection of RPW in vast farms. With...
Article
Full-text available
The advent of the ‘lab-on-fiber’ concept has boosted the prosperity of optical fiber-based platforms integrated with nanostructured metasurface technology which are capable of controlling the light at the nanoscale for multifunctional applications. Here, we propose an endless single-mode large-mode-area photonic crystal fiber (LMA-PCF) integrated m...
Article
In intensity-modulation and direct-detection (IM/DD) fiber-optic communications, it is hard to pre- or post-compensate for chromatic dispersion (CD) by digital signal processing due to one-dimensional modulation and detection. In this Letter, we propose joint optical and digital signal processing to effectively compensate for CD-caused distortions...
Article
Full-text available
A cost-effective optical performance monitoring (OPM) scheme is proposed to realize modulation format identification (MFI), baud rate identification (BRI), chromatic dispersion identification (CDI) and optical signal-to-noise ratio (OSNR) estimation of optical signals simultaneously. This technique is based on multi-task learning (MTL) neural netwo...
Conference Paper
Full-text available
Effect of bandwidth of direct detection receiver on multiparameter optical performance monitoring," ABSTRACT Our proposed optical performance monitoring (OPM) technique, based on the multi-task learning, is able to realize modulation format identification (MFI), baud rate identification (BRI), chromatic dispersion identification (CDI), and optical...
Article
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...
Article
An optical fiber interferometer-based ballistocardiography (BCG) monitoring system aided with the IJK complex detection algorithm is proposed in this paper. A new phase modulation method based on a moving-coil transducer is developed to address the problem of signal fading in the optical fiber interferometer and keep the system in quadrature by the...
Article
Full-text available
The first results of the study on photobleaching and thermally induced recovery in Bi-doped phosphosilicate fiber have been presented. It was revealed that the rate of bleaching of phosphor-related Bi active center (BAC-P) becomes slower with the decrease of photon energy. The quadratic dependence of the bleaching rate of BAC-P on laser power is ob...
Article
Anisotropic diffusion (AD) is employed to enhance the signal-to-noise ratio (SNR) of Brillouin distributed optical fiber sensor. A Brillouin optical time-domain analyzer (BOTDA) with 99-km-long fiber under test is set up, where a section of 2.3 m and another 182 m section at the end of the fiber are heated for experimental verification. The SNR of...
Article
In this paper, we propose adaptive channel-matched detection (ACMD) to effectively compensate channel distortions for C-band 64-Gbit/s intensity-modulation and direct-detection (IM/DD) optical on-off keying (OOK) system over a 100-km dispersion-uncompensated link. The proposed ACMD can adaptively compensate most of the link distortions based on cha...
Article
In this paper, an asynchronous single channel sampling (ASCS) based joint modulation format and baud rate identification (MF–BRI) method is proposed for M-QAM optical systems using Convolutional Neural Network (CNN), which significantly reduces the cost and complexity of monitoring system setup. Based on the three influencing factors of OSNR, CD an...
Article
Few-mode and multi-core fibers are proposed and demonstrated for contactless vital signs monitoring in this paper. In-line optical fiber interferometers using few-mode and multi-core fibers are designed and offset splicing is utilized for mode excitation. Extinction ratio and insertion loss are analyzed experimentally under different offset distanc...
Preprint
In this paper, we propose adaptive channel-matched detection (ACMD) for C-band 64-Gbit/s intensity-modulation and direct-detection (IM/DD) optical on-off keying (OOK) system over a 100-km dispersion-uncompensated link. The proposed ACMD can adaptively compensate most of the link distortions based on channel and noise characteristics, which includes...
Article
We propose a bend-insensitive grapefruit-type holey ring-core fiber to support orbital angular momentum (OAM) modes. The large air domain in the cladding results in a large refractive index contrast between the ring-core and the cladding, which makes this fiber bend-insensitive and makes the vector eigenmodes well separated. Therefore, the proposed...
Article
We first design and optimize a hollow-core conjoined-tube antiresonant fiber (CT-ARF) for weakly coupled LP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> and LP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> modes transmission. The cri...
Article
To the best of our knowledge, for the first time, we propose an adaptive moment estimation (Adam) algorithm based on batch gradient descent (BGD) to design a time-domain equalizer (TDE) for pulse-amplitude modulation (PAM)-based optical interconnects. The Adam algorithm has been applied widely in the fields of artificial intelligence. For TDE, the...
Conference Paper
We propose a novel demodulation method of strong FBG sensor array based on wavelength-to-time mapping and multiloop OEO. The oscillating frequency shift caused by the time shift encodes measurable variation and location information.
Article
In this Letter, we present a record C-band 56 Gbit/s intensity-modulation/direct-detection optical on/off keying (OOK) system over a 100 km dispersion-uncompensated link using only the receiver-side digital signal processing (DSP). The proposed DSP mainly includes an adaptive moment estimation (Adam)-based polynomial nonlinear equalizer (PNLE), aut...
Article
A method of robust and fast temperature extraction for Brillouin optical time-domain analyzer (BOTDA) sensing systems using the denoising autoencoder (DAE) based deep neural networks (DNN) is demonstrated. After appropriate training, the DAE suppresses the noise on the measured Brillouin gain spectrum (BGS), and improves the signal-to-noise ratio (...