We design and fabricate an on-substrate bowtie photonic crystal (PhC) cavity in silicon. By optimizing the bowtie shapes in the unit cells of the PhC cavity, the maximum of the electric field can be highly confined in the bowtie tips. Due to such confinement, an ultra-low mode volume of ∼0.1(λ/n) is achieved, which is more than an order of magnitude smaller than the previous on-substrate nanobeam cavities. An ultra-high quality (Q) factor as large as 10 is predicted by simulation, and up to 1.4×10 is measured in experiment. The observation of pronounced thermo-optic bistability is consistent with the strong confinement of light in the cavities.
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http://dx.doi.org/10.1364/OE.27.030692 | DOI Listing |
Nanophotonics
January 2024
State Key Laboratory of Extreme Photonics and Instrumentation, Center for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Ningbo Innovation Center, Zhejiang University, Hangzhou 310058, China.
The weakly ionized plasma in the Earth's ionosphere is controlled by a complex interplay between solar and magnetospheric inputs from above, atmospheric processes from below, and plasma electrodynamics from within. This interaction results in ionosphere structuring and variability that pose major challenges for accurate ionosphere prediction for global navigation satellite system (GNSS) related applications and space weather research. The ionospheric structuring and variability are often probed using the total electron content (TEC) and its relative perturbations (dTEC).
View Article and Find Full Text PDFSensors (Basel)
November 2024
State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China.
As the mainstream type of gas sensors, metal oxide semiconductor (MOS) gas sensors have garnered widespread attention due to their high sensitivity, fast response time, broad detection spectrum, long lifetime, low cost, and simple structure. However, the high power consumption due to the high operating temperature limits its application in some application scenarios such as mobile and wearable devices. At the same time, highly sensitive and low-power gas sensors are becoming more necessary and indispensable in response to the growth of the environmental problems and development of miniaturized sensing technologies.
View Article and Find Full Text PDFWe propose and experimentally demonstrate an injection-locked broadband optoelectronic oscillator (OEO) to generate freely tunable phase-locked dual-frequency microwave signals. When two single-tone signals inside and outside the passband of the electrical broadband bandpass filter (BPF) are, respectively, injected into the OEO, a phase-locked dual-frequency microwave signal with ultra-low near-end side-mode spurs can be generated from the OEO cavity. Therefore, one frequency of the output signal is equal to the frequency of the injected signal within the BPF, and the other frequency is equal to the sum frequency or the differential frequency of two injected signals.
View Article and Find Full Text PDFWe present two distinct ultra-low frequency noise lasers at 729 nm with a fast frequency noise of 30 Hz/Hz, corresponding to a Lorentzian linewidth of 0.1 kHz. The characteristics of both lasers, which are based on different types of laser diodes, are investigated using experimental and theoretical analysis with a focus on identifying the advantages and disadvantages of each type of system.
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