Thermo-optic switch based on double-slot photonic crystal waveguide is demonstrated, high extinction ratio of 17 dB has been experimentally achieved under a switching power as low as 9.2 mW while the device is only 16-µm-long.
Music is important in everyday life because it affects our emotions while changing the rhythm within our own body. With the popularity of music, targeted and personalized music is extra important to people. We have built such an interactive system, which plays melodies with different rhythms based on the real-time heart rate of the human body, which can also be generated by adjusting different types of musical elements. It is studied that through data interaction, the changes of human physiological signals measured in real time are used as the medium, and the fluctuations are associated with the music generation through programming, and then the real-time generated melody is played to the test subjects to initially form a closed loop of the system. The system introduces the concept of real-time feedback, highlighting methods that combine musical and physiological signals. Altogether, this study provides preliminary prerequisites for a viable computational application using physiological responses in real life. Future research directions and applications are also suggested.
We demonstrate a compact thermo-optic variable optical attenuator (VOA) based on the cutoff effect of W1 photonic crystal waveguide (PCW). In experiment, a variable attenuation range of 29 dB is achieved with a device length of only 16.8 μm. The coupling loss is also reduced by 7.5±2.5 dB through introducing low-group-index tapers between the W1 PCW and strip waveguide. This VOA provides the largest variable attenuation range in the reported tunable PCW device to our knowledge.
The composition, elastic strain, and structural defects of an InGaN/GaN multiple quantum well (MQW) are investigated using a combination of x-ray diffraction, transmission electron microscopy, and Rutherford backscattering/channeling. None of the applied techniques alone can unambiguously resolve the thickness of the individual layers, the In composition in the wells, and the elastic strain. These three parameters directly determine the optical properties of the MQW. It is shown that only a combination of these measurements reveals the full structural characterization of the nitride multilayer. A clear correlation between the defect density of In distribution and strain relaxation is evidenced. The experimental result of the ratio of the average perpendicular elastic strain 〈e⊥〉 and the average parallel elastic strain 〈e∥〉, 〈e⊥〉/〈e∥〉=−0.52, is in excellent agreement with the value deduced from the elastic constants.
With the rapid development of data analysis technology, the implementation of smart grid construction, the mass installation and use of smart sensing devices, the combination of data analysis technology and smart grid is an inevitable trend. The power data will bring great benefits to power companies. Among them, the topology estimation of distribution network is the cornerstone of smart grid data analysis technology. This paper firstly introduces the voltage deviation analysis of the users on the distribution network, and uses the relationship to conduct a series of topology analysis of the distribution network, such as topology verification, phase identification and topology estimation. The data used in this paper is the actual electricity data of a city, and the result of topology verification is validated through actual investigation.
In this paper, we propose and demonstrate a novel microwave photonics architecture consisting of a transmitter and a receiver, designed for spread spectrum communication. The transmitter is capable of spreading and up-converting a baseband signal to a wideband spread spectrum signal at a frequency of 10 GHz. On the other hand, the receiver can despread and down-convert the wideband spread spectrum signal back to the baseband signal. The architecture exhibits remarkable capabilities in handling large instantaneous bandwidth signals across a wide operating band, making it suitable for various application scenarios. Additionally, our experimental results highlight the architecture's excellent performance in image suppression (up to 56 dB) and dynamic range (SFDR3: 127.2 $\text{dB}\cdot \text{Hz}^{2/3})$ .
Adaptive camouflage in thermal imaging, a form of cloaking technology capable of blending naturally into the surrounding environment, has been a great challenge in the past decades. Emissivity engineering for thermal camouflage is regarded as a more promising way compared to merely temperature controlling that has to dissipate a large amount of excessive heat. However, practical devices with an active modulation of emissivity have yet to be well explored. In this letter we demonstrate an active cloaking device capable of efficient thermal radiance control, which consists of a vanadium dioxide (VO2) layer, with a negative differential thermal emissivity, coated on a graphene/carbon nanotube (CNT) thin film. A slight joule heating drastically changes the emissivity of the device, achieving rapid switchable thermal camouflage with a low power consumption and excellent reliability. It is believed that this device will find wide applications not only in artificial systems for infrared camouflage or cloaking but also in energy-saving smart windows and thermo-optical modulators.
We present a photonic based broadband DSSS system with photonic matched filter. The optical delay line and optical switch-based encoder/decoder is used in signal spreading/de-spreading. The simulation results show that the photonic matched filter could achieve fast acquisition of PN sequence.
Resonance lineshapes of a side-coupled waveguide-microring resonator (MRR) is crucial for the performances of MRR-based on-chip photonic devices. Much efforts have been made to modify the resonance lineshapes to other types, such as asymmetric Fano profiles. However, complex photonic structures are required to integrate with waveguide-MRR. Here, we model the light propagation in a waveguide-MRR into the interactions of a discrete resonance mode and a continuum waveguiding mode and propose the phase delay between the two states plays great roles in controlling the resonance lineshape into symmetric Lorentzian dips, Lorentzian peaks, and Fano lineshapes with arbitrary asymmetric factors. We experimentally verify this by fabricating silicon waveguide-MRR with an air-hole inserted in the bus-waveguide section coupled with the MRR, where the air-hole with varied dimensions could control the phase delay. The results not only have potentials to strengthen the performances of MRR-based devices, but also provide a simple strategy to control resonance lineshapes in other optical resonators, including photonic crystal cavity, microtoroid, etc.
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