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Coherent optical receivers have been widely used in free-space optical communication. We report on a coherent receiver with a homodyne optical phase-locked loop using a Costas loop. Differing from the conventional configuration, the demonstration in this paper with enhanced dynamic performance using an auxiliary acquisition and locking circuitry is able to achieve fast phase locking to signal laser...
In this paper, a free-space optical (FSO) communication system with supercontinuum source generated by dispersion shift fiber (DSF) from pulsed light modulated by optical switches is designed and constructed. In addition, the experimental results of free-space optical communication between broadband and narrowband light source are compared. Verifying the feasibility of broad-spectrum FSO communication...
We have proposed a novel hybrid software and hardware equalization scheme based on digital zero-padding pre-equalization and differential reception. We have experimental demonstrated a red LED based visible light communication system over 1-meter free space transmission with the measured BER below 7% FEC threshold. The signal is QAM-DMT modulated and the modulation level is varying from 32QAM to 128QAM...
Turbulent environment can highly affect the performance of free space optical (FSO) communication links. Therefore, how to obtain the turbulence intensity is a very important issue. The paper has shown the detailed analysis to calculate the log irradiance variance (σ2R) along with the experimental verification under an indoor laboratory controlled turbulence condition. This paper verifies the consistency...
To solve the phase deviation problem caused by antenna orientation centre deviation during the phase calibration of Monopulse tracking receiver on ship-borne sitcom station, a phase compensation method is proposed to enhance the phase calibration precision. The working principle of monopulse tracking receiver is discussed, the demodulation process of sum and difference signal, and the cause of phase...
This paper investigates the performance of underwater visible light communications (UVLC) systems employing multiple transmitters and/or multiple receivers to exploit the advantage of spatial diversity. Experimental results are further provided to evaluate the error performance of single input multiple outputs (SIMO), multiple inputs single output (MISO) and multiple inputs multiple outputs (MIMO)...
The non-line-of-sight ultraviolet single-scatter approximate model is usually used to study the channel characteristics and system performance due to its simplification. In this paper, a performance evaluation system based on the approximate model is established, which includes four aspects, namely, packet error rate, average transmitting power, bandwidth utilizing efficiency and data transmission...
This paper proposes a statistical method to detection of Topological Charges (TCs) based on calculating the similarity factor (SF) between the instantaneous crosstalk distribution and the standard crosstalk distributions. The values of SF are time-varying, and we set a threshold to recognize TCs. Then, the probability density function (PDF) of the SF is obtained to estimate error rate of TC detection...
The GaAsP/Si dual-junction solar cells have been systematically investigated in our paper by using AMPS (Analysis of Microelectronic and Photonic Structures). Based on the optimized results of single-junction solar cells, we propose a promising method to improve the properties of the dual-junction solar cell. And the monolithic GaAsxP1−x/Si dual-junction solar cells with various As compositions (x=0...
The wavefront compensation effect of the micro corner-cube-reflector arrays (MCCRAs) in modulating retroreflector (MRR) free-space optical (FSO) link is investigated by wave-optics (WO) simulation method that is based on the split-step beam propagation method and phase screen theory. Two kinds of the MCCRAs with the cell's apertures of the triangle and hexagon are considered with the aid of the numerical...
High radio-frequency phase-coded waveform generation based on dispersion-compensated optoelectronic oscillator (DCOEO) is proposed and experimentally demonstrated. The carrier frequency range of the generated phase-coded microwave, which exactly varies from 4 GHz to 45 GHz, can cover Ka band for Radar applications.
The attractive use of microwave photonic (MWP) technologies brings about immense benefits to the field of optical sensing. Recent new developments in microwave photonic signal processing techniques that have high potentialities to be used in a variety of sensing applications are presented in the paper, including exploring the use of finite impulse response MWP filters for distributed sensing applications,...
In this paper, a novel microfiber refractive index sensor prepared with tapering-twisting-tapering technique has been proposed and demonstrated for the first time. Experimental results show that the interference intensity of the novel microfiber increases with the increment of pre-tapered length and the intervening twist number. Furthermore, the refractive index sensitivity of this microfiber sensor...
A new scheme for fabricating microtapered long-period fiber gratings (LPFGs) and helical LPFGs is proposed and demonstrated successfully by periodically tapering and twisting a standard single-mode fiber, respectively, using a CO2 laser fusion splicer as heater. In comparison to previous fabrication methods, our scheme can significantly improve the quality of the microtapered and helical LPFGs. Considering...
The resonant fiber-optic gyroscope (RFOG) based on the Sagnac effect is a high-accuracy rotation sensor. The intermodulation error due to the laser noise at even harmonics of the modulation frequency deteriorates the performance of the RFOG. Aiming at the suppression of high-frequency laser noise, a phase-modulated feedback loop is developed and analyzed. The parameters of the servo loop is optimized...
In this paper, a fiber-optic sensing system for simultaneous measurement of temperature and transversal loading based on a fiber-ring microwave photonic filter (MPF) has been proposed and experimentally demonstrated. The temperature variation will induce the central frequency shift of the MPF's passband, while the micro-bend loss induced by transversal loading will cause the change of extinction ratio...
As the differences in user business demand increasing, in order to effectively reduce the network delay and improve resource utilization, a High-priority Assignment First Dynamic Wavelength and Bandwidth Allocation algorithm (HAF-DWBA) in TWDM-PON is proposed. According to the Service-Level Agreement to determine the priority of ONUs, this algorithm can implement five types of T-CONT and four kinds...
Both channel and phase noise blind recover are proposed and demonstrated to recover the orthogonal-frequency-division-multiplexing (OFDM) signal without using any training symbols or pilot subcarriers in direct-detection optical OFDM. The proposed receivers can achieve similar performance compared to conventional OFDM receivers.
In this paper, we propose a block decision-aided (BL-DA) laser phase noise (LPN) estimation algorithm for coherent optical OFDM (CO-OFDM) systems. The OFDM symbols are divided into several blocks and the LPN estimation and compensation procedure is performed based on the decisions between these blocks. The proposed BL-DA algorithm can be applied for higher LPN estimation while at the same time ensuring...
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