Feiliang Chen

Bio: Feiliang Chen is an academic researcher from China Academy of Engineering Physics. The author has contributed to research in topics: Materials science & Optoelectronics. The author has an hindex of 8, co-authored 53 publications receiving 320 citations. Previous affiliations of Feiliang Chen include Chinese Academy of Sciences.

A high-performance blue filter for a white-led-based visible light communication system

Abstract: A high-performance blue filter was demonstrated and employed to increase the modulation bandwidth and dramatically reduce the bit error rate of a white-LED-based VLC system. It has a very wide stopband (500–1050 nm), high transmittance passband (average 97.5 percent in the blue signal range of 430–485 nm), and a sharp and precise cutoff edge. Not only can the blue filter completely remove the slow phosphorescent component from modulated signals, but it can also effectively reject ambient solar radiation. Meanwhile, the blue light signals of the LED can almost be retained. This results in a high SNR and improves the performance of a VLC system, including increased modulation bandwidth and reduced BER. The BER can be dramatically reduced from 3.6 × 10–2 to 1.7 × 10–4 at 50 MHz bandwidth, and from 2.6 × 10–2 to 1.9 × 10–5 at a distance of 30 cm compared to a VLC system without our blue filter. More importantly, the stop band covers the whole response range of the receiver except for the blue signal band, which strongly increases the ability of a VLC system used in the sun or outdoors.

Tuning phase transition temperature of VO 2 thin films by annealing atmosphere

Abstract: A simple new way to tune the optical phase transition temperature of VO2 films was proposed by only controlling the pressure of oxygen during the annealing process. Vanadium films were deposited on glass by a large-scale magnetron sputtering coating system and then annealed in appropriate oxygen atmosphere to form the VO2 films. The infrared transmission change (at 2400 nm) is as high as 58% for the VO2 thin film on the glass substrate, which is very good for tuning infrared radiation and energy saving as smart windows. The phase transition temperature of the films can be easily tuned from an intrinsic temperature to 44.7 °C and 40.2 °C on glass and sapphire by annealing oxygen pressure, respectively. The mechanism is: V3+ ions form in the film when under anaerobic conditions, which can interrupt the V4+ chain and reduce the phase transition temperature. The existence of V3+ ions has been observed by x-ray photoelectron spectroscopy (XPS) experiments as proof.

Control of optical properties of TiN_xO_y films and application for high performance solar selective absorbing coatings

Abstract: TiNxOy films with controllable optical properties have been fabricated by reactive mid-frequency magnetron sputtering from titanium nitride target. The optical and electrical properties were studied as a function of the reactive gas flow and were correlated with the film stoichiometry. The results showed that the behavior of TiNxOy films can be adjusted from metallic to dielectric by increasing oxygen content, which is of great significance to their extensive applications. Owing to the accurate control of optical properties, a TiNxOy based solar selective absorbing coating has been designed and prepared with the aid of TiO2/Si3N4/SiO2 antireflection layers. Its solar absorbance is as high as 97.5% and thermal emissivity is 4.3% with total thickness of 230 nm. The solar absorbance can maintain above 90% for a broad incident angle range from 0° to 65°.

High performance colored selective absorbers for architecturally integrated solar applications

Abstract: Architecturally integrated solar thermal technologies such as solar water heaters and solar thermoelectric generators (STEGs) rely on spectrally selective solar absorbers. These solar absorbers need to have simultaneous high solar absorptivity (α) and low thermal emissivity (e), which always makes them look dark blue or black and so blocks architectural integrated solar applications. A colorful appearance should be taken into account for integration into architectural applications. Herein, colored absorbers with a TiNxOy absorbing layer and a TiO2/Si3N4/SiO2 dielectric stack are elaborately designed and can be fabricated with only two targets, Ti and Si, by using reactive magnetron sputtering. Both the theoretical and experimental results show that the color can be tuned a huge amount, while keeping solar absorptivity higher than 95% and thermal emissivity lower than 5%. The highest absorptivity and energy efficiency (α/e) values are 97.6% and 27.2, respectively. These materials can also be fabricated onto thermoelectric generators to demonstrate the conversion of solar energy into electricity. The open circuit voltage dramatically increases from 171 mV to 523 mV (3.1 times) when using the absorbers. Additionally, the colored solar absorbers can be deposited onto most types of substrate, even flexible substrates. They can simultaneously satisfy the aesthetic requirements and excellent energy performance required for architecturally integrated solar thermal and thermoelectric applications, as well as applications in other fields.

Colorful solar selective absorber integrated with different colored units

Abstract: Solar selective absorbers are the core part for solar thermal technologies such as solar water heaters, concentrated solar power, solar thermoelectric generators and solar thermophotovoltaics. Colorful solar selective absorber can provide new freedom and flexibility beyond energy performance, which will lead to wider utilization of solar technologies. In this work, we present a monolithic integration of colored solar absorber array with different colors on a single substrate based on a multilayered structure of Cu/TiNxOy/TiO2/Si3N4/SiO2. A colored solar absorber array with 16 color units is demonstrated experimentally by using combinatorial deposition technique via changing the thickness of SiO2 layer. The solar absorptivity and thermal emissivity of all the color units is higher than 92% and lower than 5.5%, respectively. The colored solar selective absorber array can have colorful appearance and designable patterns while keeping high energy performance at the same time. It is a new candidate for a number of solar applications, especially for architecture integration and military camouflage.

Quantum emission from hexagonal boron nitride monolayers

Abstract: We demonstrate first room temperature, and ultrabright single photon emission from a color center in two-dimensional multilayer hexagonal boron nitride. Density Functional Theory calculations indicate that vacancy-related centers are a likely source of the emission.

Plasmonic colour generation

Abstract: Plasmonic colours are structural colours that emerge from resonant interactions between light and metallic nanostructures. The engineering of plasmonic colours is a promising, rapidly emerging research field that could have a large technological impact. We highlight basic properties of plasmonic colours and recent nanofabrication developments, comparing technology-performance indicators for traditional and nanophotonic colour technologies. The structures of interest include diffraction gratings, nanoaperture arrays, thin films, and multilayers and structures that support Mie resonances and whispering-gallery modes. We discuss plasmonic colour nanotechnology based on localized surface plasmon resonances, such as gap plasmons and hybridized disk–hole plasmons, which allow for colour printing with sub-diffraction resolution. We also address a range of fabrication approaches that enable large-area printing and nanoscale lithography compatible with complementary metal-oxide semiconductor technologies, including nanoimprint lithography and self-assembly. Finally, we review recent developments in dynamically reconfigurable plasmonic colours and in the laser-induced post-processing of plasmonic colour surfaces. Plasmonic colours can be used to colour large surfaces, can be mass-produced and dynamically reconfigured, and can provide sub-diffraction resolution. In this Review, basic properties of plasmonic colours, different platforms supporting them and recent developments in the field are discussed.

Pathways and challenges for efficient solar-thermal desalination

Abstract: Solar-thermal desalination (STD) is a potentially low-cost, sustainable approach for providing high-quality fresh water in the absence of water and energy infrastructures. Despite recent efforts to advance STD by improving heat-absorbing materials and system designs, the best strategies for maximizing STD performance remain uncertain. To address this problem, we identify three major steps in distillation-based STD: (i) light-to-heat energy conversion, (ii) thermal vapor generation, and (iii) conversion of vapor to water via condensation. Using specific water productivity as a quantitative metric for energy efficiency, we show that efficient recovery of the latent heat of condensation is critical for STD performance enhancement, because solar vapor generation has already been pushed toward its performance limit. We also demonstrate that STD cannot compete with photovoltaic reverse osmosis desalination in energy efficiency. We conclude by emphasizing the importance of factors other than energy efficiency, including cost, ease of maintenance, and applicability to hypersaline waters.

1.6 Gbit/s phosphorescent white LED based VLC transmission using a cascaded pre-equalization circuit and a differential outputs PIN receiver.

Abstract: We proposed a cascaded amplitude equalizer used for high speed visible light communications (VLC) system. With the cascaded pre-equalization circuit, the -3dB bandwidth of VLC system can be extended from 17MHz to 366MHz using a commercially available phosphorescent white LED, a blue filter and a differential outputs PIN receiver. The data rate is 1.60Gbit/s exploiting 16QAM-OFDM with 400MHz modulation bandwidth over 1m free-space transmission under pre-forward error correction (pre-FEC) limit of 3.8 × 10(-3). To our knowledge, this is the highest data rate ever achieved by using a commercially available phosphorescent white LED in VLC system.

Controlling the Polarization State of Light with a Dispersion-Free Metastructure

Abstract: Metamaterials, artificial structures with unexpected properties, only function over a limited spectral window. Scientists have recently determined that the technique of combining a metallic metamaterial with a dielectric interlayer creates a device that modulates light over a wide range of frequencies.