Search Results - Deming Liu

Digital coherent combining (DCC) technique can increase the free space optical signal collection area by combining the signals received by an array of small apertures in a coherent manner. To realize DCC the different versions of signals must be aligned in phase by the digital phase alignment algori...

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Integrating multiple functionalities into one single device is of great importance for ever-growing demand of photonic device. Optical vortex beam contains orbital angular momentum (OAM) and spin angular momentum (SAM) associated with phase and polarization singularities respectively, which has cont...

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Single-photodiode-per-polarization coherent receivers (SCRs) can preserve all of the merits of the conventional digital coherent receivers (DCRs) such as supporting chromatic dispersion (CD) compensation and polarization multiplexing, whilst have much lower optical complexity. But the overall algori...

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The reference optical spectrum (ROS) based in-band optical signal-to-noise-ratio (OSNR) monitoring methods are accurate and inherently robust to fiber chromatic dispersion and polarization mode dispersion. They are also very simple and suitable to be deployed ubiquitously in the transmission system....

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We propose a novel method for the deterministic formation and manipulation of a single cavity soliton (CS) in anomalous dispersion microresonators via parametric seeding. Our numerical simulations demonstrate that, through choosing a proper power, a seed signal which is one free-spectral range (FSR)...

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The free space optical communication (FSOC) signals often exhibit a much larger dynamic range and much lower OSNR than optical fiber communication signals, due to the large-scale relative motion of the terminals, change of atmospheric channel conditions and large transmission loss. For this reason f...

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We develop a two-step infrared (IR) femtosecond fiber laser exposure technique to flexibly fabricate long period fiber gratings (LPFGs) with a high peak band-rejection efficiency of 35.4 dB, insertion loss of 4.36 dB, and 3 dB bandwidth of 13 nm. First, we...

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In this paper, we propose our observation, analysis, and alleviation method of the beat frequency fluctuation in short-cavity dual-polarization distributed Bragg reflector (DBR) fiber grating laser sensor in time and frequency domain. According to our observation, beat frequency fluctuation varies f...

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High-resolution optical spectroscopy is a significant approach to reveal the inherent laws of devices and systems. Although optical spectrum analyzer (OSA) based on stimulated Brillouin scattering (SBS) has achieved a resolution of ∼10 pm, when the signal power increases, the Brillouin ga...

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We propose and experimentally demonstrate an all-fiber tunable <inline-formula><tex-math notation="LaTeX"> ${\rm{LP}}_{11}$</tex-math></inline-formula> mode rotator with 360&#x00B0; range, based on the bending and twisting of the two-mode fiber (TMF). A theoreti...

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We propose a simultaneous optical signal recognition (OSR) and optical signal-to-noise ratio (OSNR) monitoring method by using multi-task learning convolutional neural network (MTL-CNN) in conjunction with optical spectrums, which enables optical performance monitoring (OPM) in the optical transmiss...

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A simple and efficient manufacture method of helical long period fiber grating (HLPFG) in a single-mode fiber (SMF) is designed and verified through experiment. Different from the previous fabricating methods, the SMF is heated by a double-side CO₂ laser beam after being twist...

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Acoustic measurement is the most widely used non-electric method to detect partial discharge (PD) signals by detect the ultrasonic waves arisen from partial discharge. To solve the shortages of low sensitivity and susceptibility to interferences, a gold diaphragm based Fabry-Perot interferometer ult...

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A low-complexity adaptive equalizer including equalization, rotation of state of polarization (RSOP) tracking, and phase recovery is proposed for coherent optical polarization-division-multiplexing (PDM) quadrature phase-shifting keying (QPSK) transmission system. A conventional N-tap 2 &#x00D7;...

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A novel highly nonlinear optical fiber with enhanced stimulated Brillouin scattering for narrow-band filtering is proposed. Herein, we initially discuss the tailoring of the Brillouin gain spectrum in germanium and fluorine co-doped single cladding fibers. By adjusting the fiber structure and the do...

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High sensitivity, small size, light weight and low power are the most critical requirements for the lasercom terminals used in free space optical communication (FSOC) systems. Coherent receivers have an exceptionally high sensitivity but their optical complexity and power consumption are too high, e...

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Polarization-maintaining (PM) all-fiber cavity is always essential to realize stable ultrafast-pulse generation. With the help of five sections of PM fibers with independently specific splicing angles, we successfully obtain a femtosecond pulse output from a PM Ytterbium-doped fiber laser (YDFL) mod...

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In the optical communication systems, the optical spectrum (OS) provides useful informations for optical performance monitoring and optical link diagnosis. In this paper, we investigate the neural-network based OS analysis (OSA) techniques able to simultaneously recognize the OS and estimate the opt...

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Based on electrical arc discharges mechanisms, we inscribed spatially arrayed long period gratings (LPGs) into a heterogeneous seven-core fiber. The LPG fabrication platform was built upon the commercial fiber fusion splicer with a self-developed real-time control software. With the help of homemade...

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In this paper, in order to achieve low differential mode group delay (DMGD) over the C&#x002B;L band, we propose the hole-assisted graded-index few mode fiber (FMF) design supporting four nondegenerated linear polarized (LP) modes for a mode division multiplexing system. In order to determine th...

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