Low complexity OFDM VLC system enabled by spatial summing modulation.

Commercial-off-the-shelf (COTS) devices enabled visible light communication (VLC) for Internet of things (IoT) applications has attracted extensive attentions from both academic and industrial communities, thanks to the pervasive deployments of light emitting diode (LED) lighting infrastructure. However, due to the limitation of frequency response and non-linearity of the commercial illuminating LED light consisting of multiple LED chips, the achievable data rate is far less than that provided by the experimental VLC system with a single LED with specialized devices, e.g.

Secure and private NOMA VLC using OFDM with two-level chaotic encryption.

In this paper, we propose and demonstrate a secure and private non-orthogonal multiple access (NOMA) based visible light communication (VLC) system. Orthogonal frequency division multiplexing (OFDM) modulation is applied in the system and a two-level chaotic encryption scheme is further implemented, which can guarantee both the security of legitimate users against eavesdroppers and the privacy among all the legitimate users. An experimental demonstration with two legitimate users and one eavesdropper successfully verifies the feasibility of the proposed secure and private NOMA VLC system.

Column generation algorithms for virtual network embedding in flexi-grid optical networks.

Network virtualization provides means for efficient management of network resources by embedding multiple virtual networks (VNs) to share efficiently the same substrate network. Such virtual network embedding (VNE) gives rise to a challenging problem of how to optimize resource allocation to VNs and to guarantee their performance requirements. In this paper, we provide VNE algorithms for efficient management of flexi-grid optical networks.

Improving performance of channel equalization in RSOA-based WDM-PON by QR decomposition.

In reflective semiconductor optical amplifier (RSOA)-based wavelength division multiplexed passive optical network (WDM-PON), the bit rate is limited by low modulation bandwidth of RSOAs. To overcome the limitation, we apply QR decomposition in channel equalizer (QR-CE) to achieve successive interference cancellation (SIC) for discrete Fourier transform spreading orthogonal frequency division multiplexing (DFT-S OFDM) signal. Using an RSOA with a 3-dB modulation bandwidth of only ~800 MHz, we experimentally demonstrate a 15.

Investigation of PMD in direct-detection optical OFDM with zero padding.

We investigate the polarization-mode dispersion (PMD) effect of zero padding OFDM (ZP-OFDM) in direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM) systems. We first study the conventional equalization method for ZP-OFDM. Then an equalization method based on sorted QR decomposition is proposed to further improve the performance.

An efficient energy-saving scheme incorporating dozing and sleep modes for CLS-based WDM-PONs with colorless ONUs.

We propose and demonstrate an efficient energy-saving scheme incorporating dozing and sleep modes for WDM-PONs with centralized light sources (CLS). The novel scheme is based on simple power detection and local transmission request. Two logic control units are designed to switch the operation modes of the respective ONUs and their associated transceivers in the OLT.

Performance of dimming control scheme in visible light communication system.

We investigate the performance of visible light communication (VLC) system with a pulse width modulation (PWM) dimming control scheme. Under this scheme, the communication quality in terms of number of transmitted bits and bit error rate (BER) of less than 10(-3) should be guaranteed. However, for on-off-keying (OOK) signal, the required data rate becomes 10 times as high as the original data rate when the duty cycle of dimming control signal is 0.

Performance improvement of on-off-keying free‑space optical transmission systems by a co‑propagating reference continuous wave light.

In this paper, we analytically investigate an optical signal detection scheme to mitigate the scintillation effect with the assistance of a co-propagating reference continuous wave (CW) light. Using the correlation coefficient between the intensities of the data light and the reference CW light, we mathematically derive their joint intensity distributions under two widely used atmospheric turbulence channel models, namely log-normal distributed channel model and Gamma-Gamma distributed channel model, respectively. We also carry out the Monte-Carlo (MC) simulation and show that theoretical results agree with simulation results well.

Performance of a novel LED lamp arrangement to reduce SNR fluctuation for multi-user visible light communication systems.

This paper investigates the performance of our recently proposed LED lamp arrangement to reduce the SNR fluctuation from different locations in the room for multi-user visible light communications. The LED lamp arrangement consists of 4 LED lamps positioned in the corners and 12 LED lamps spread evenly on a circle. Our studies show that the SNR fluctuation under such a LED lamp arrangement is reduced from 14.

Performance improvement by tilting receiver plane in M-QAM OFDM visible light communications.

We propose a scheme to improve the SNR distribution as well as the spectral efficiency of M-QAM OFDM signal for indoor visible light communication by tilting the receiver plane. Newton method is employed for the photo-detector to receive maximum power by finding the optimal tilting angle. This method is a fast algorithm that only three searching steps are needed.

Multipoint free-space optics system for short-range communications between flight platforms.

The problems associated with using typical free-space optics (FSO) transceivers for multipoint communications on flight platforms, such as satellites and unmanned aerial vehicles, in a cluster are discussed and the transceivers are found to be unsuitable for concurrent multipoint communications in those platforms. To overcome the problems, a multipoint FSO system design is proposed. The design of the multipoint system is described and the performance of the multipoint receiver is evaluated in terms of receive gain under different conditions.

Beam divergence changing mechanism for short-range inter-unmanned aerial vehicle optical communications.

The problems associated with using a single fixed beam divergence for short-range inter-unmanned aerial vehicle free-space optical communications are discussed. To overcome the problems, a beam divergence changing mechanism is proposed. Four different methods are then proposed to implement the beam divergence changing mechanism.

Fiber-optic parametric amplifier and oscillator based on intracavity parametric pump technique.

A cost-effective fiber optical parametric amplifier (FOPA) based on the laser intracavity pump technique has been proposed and demonstrated experimentally. The parametric process is realized by inserting a 1 km highly nonlinear dispersion-shifted fiber (HNL-DSF) into a fiber ring-laser cavity that consists of a high-power erbium-doped fiber (EDF) amplifier and two highly reflective fiber Bragg gratings. Compared with the conventional parametric pump schemes, the proposed pumping technique is free from a tunable semiconductor laser as the pump source and also the pump phase modulation.

Stable and spacing-adjustable multiwavelength Raman fiber laser based on mixed-cascaded phosphosilicate fiber Raman linear cavity.

A novel multiwavelength Raman fiber laser based on the mixed-cascaded Stokes effects of phosphosilicate fiber is proposed and demonstrated experimentally. By using stimulated Raman scattering of both P(2)O(5) and SiO(2) along 1 km phosphosilicate fiber pumped with a 1064 nm double-clad fiber laser, the mixed-cascaded Raman linear cavity is formed by a pair of fiber Bragg gratings at 1239 nm, a polarization-maintaining fiber (PMF) Sagnac loop filter, and a conventional optical loop mirror. Up to 15-wavelength stable oscillations around 1320 nm are obtained with a wavelength spacing of 0.

Production of hybrid phage displaying secreted aspartyl proteinase epitope of Candida albicans and its application for the diagnosis of disseminated candidiasis.

The secreted aspartyl proteinases (Saps) of Candida albicans have been implicated as immunodominant antigens and virulence factors associated with adherence and tissue invasion. A hybrid phage displaying the Sap epitope VKYTS was constructed by cloning the corresponding DNA fragments into the pfd88 vector. Similar to native Sap, the phage-displayed epitope showed reactivity to sera from mice and patients with systemic C.

High-speed WDM-PON using CW injection-locked Fabry-Pérot laser diodes.

We propose a new WDM-PON architecture using Fabry-Pérot laser diodes (FP-LDs) that are injection-locked by continuous wave (CW) seed light. The modulation characteristics of the CW light injection-locked FP-LD are first investigated. Both uplink and downlink transmissions at 10 Gb/s are experimentally demonstrated using the proposed CW injection-locked FP-LDs.

New transmitter configuration for subcarrier multiplexed DPSK systems and its applications to chromatic dispersion monitoring.

We present a new transmitter configuration using a single dual-electrode Mach-Zehnder Modulator (DE-MZM) for generating DPSK signal and subcarrier simultaneously. We then apply this new configuration to monitoring chromatic dispersion (CD) in DPSK systems by detecting the RF power at both of the clock and subcarrier frequencies. Our investigations show that the method can greatly improve CD monitoring capability.

Comparison of phage pVIII and KLH as vector in inducing the production of cytokines in C57BL/6J mice.

We have demonstrated that phage display Candida albicans (C. albicans) LKVIRK epitope was protective in systemically infected C57BL/6J mice. The different development from precursor Ths, Th1 or Th2, will result in a protective or nonprotective immune response.

New bit-error-rate monitoring technique based on histograms and curve fitting.

We propose a new method for estimating the bit error rate (BER) of optical channels suffering from crosstalk and waveform distortion. We demonstrate experimentally that the new method can provide a good BER estimation with an error range less than one order of magnitude.

High-birefringence linearly chirped grating based optical device for PMD compensation.

We propose a novel delay element for polarization mode dispersion (PMD) compensation by employing a tunable high-birefringence linearly chirped grating. The device can adjust differential group delay in a linearly continuous way and its performance is demonstrated by compensating 10-Gb/s signal with the first-order PMD. The tradeoff between PMD compensation capability of the device and the power penalty caused by the chromatic dispersion of the grating has also been studied.