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Showing papers by "Daqing Zhang published in 2022"


Book ChapterDOI
01 Jan 2022
TL;DR: In this article, the authors present an overview of WiFi-based human respiration monitoring techniques, covering both pattern-based and model-based approaches, and then show how human- respiration sensing is achieved using WiFi signals and why blind spots occur sometimes using WiFi CSI amplitude.
Abstract: Human respiration monitoring plays an important role in healthcare applications, such as sleep apnea detection and sleep-stage recognition. We have witnessed a diversity of approaches developed for respiration monitoring, ranging from contact-based pulse oximeter to contact-free camera and CW (Continuous Wave) radar solutions. Recently, WiFi CSI-based contact-free sensing solutions have attracted a tremendous amount of research attention due to the pervasive deployment of WiFi infrastructure. In this chapter, we first present an overview of WiFi based-human respiration monitoring techniques, covering both pattern-based and model-based approaches. By introducing the Fresnel reflection and diffraction models, we then show how human respiration sensing is achieved using WiFi signals and why “blind spots” occur sometimes using WiFi CSI amplitude. To address the “blind spots” and short sensing-range issues, we further develop a series of solutions for single-person respiration monitoring. Finally, we also present a state-of-the-art solution for multi-person respiration sensing.

10 citations


Journal ArticleDOI
29 Apr 2022-PhotoniX
TL;DR: In this paper , an exact and robust design method for add-drop filters (ADFs) with an FSR-free operation capability, a sub-nanometer optical bandwidth, and a high out-of-band rejection (OBR) ratio was proposed.
Abstract: Abstract Free-spectral-range (FSR)-free optical filters have always been a critical challenge for photonic integrated circuits. A high-performance FSR-free filter is highly desired for communication, spectroscopy, and sensing applications. Despite significant progress in integrated optical filters, the FSR-free filter with a tunable narrow-band, high out-of-band rejection, and large fabrication tolerance has rarely been demonstrated. In this paper, we propose an exact and robust design method for add-drop filters (ADFs) with an FSR-free operation capability, a sub-nanometer optical bandwidth, and a high out-of-band rejection (OBR) ratio. The achieved filter has a 3-dB bandwidth of < 0.5 nm and an OBR ratio of 21.5 dB within a large waveband of 220 nm, which to the best of our knowledge, is the largest-FSR ADF demonstrated on a silicon photonic platform. The filter exhibits large tunability of 12.3 nm with a heating efficiency of 97 pm/mW and maintains the FSR-free feature in the whole tuning process. In addition, we fabricated a series of ADFs with different periods, which all showed reliable and excellent performances.

6 citations


Journal ArticleDOI
TL;DR: In this article , a polarization-independent electro-absorption modulator based on the trapezoid polymer-graphene waveguide (PGW) was proposed, and the modulator has a compact size and the extinction ratio (ER) of 37 dB can be achieved by reasonably setting working points of “OFF” and “ON” states with 800 μm long active graphene length.
Abstract: A polarization-independent electro-absorption modulator based on the trapezoid polymer-graphene waveguide (PGW) was proposed. The modulator was constructed on a trapezoid polymer waveguide, and the insulting dielectric spacer sandwiched in the two graphene layers was placed on the surface of the trapezoid polymer waveguide core. The simulation results show that by applying different gate voltages on the graphene layers, effective mode index of the TE and TM modes in the PGW can realize the similar changes in the C-band, which provides the possibility for realizing the polarization-independent modulation. Here, through simulation and optimization, the presented modulator has a compact size and the extinction ratio (ER) of 37 dB can be achieved by reasonably setting working points of “OFF” and “ON” states with 800 μm long active graphene length. The ER variation between the two operating modes is about 0.46 dB. The corresponding power consumption of the modulator is about 23.6 pJ/bit.

6 citations



Journal ArticleDOI
TL;DR: In this article , a polymer/silica hybrid waveguide thermo-optic variable optical attenuator (VOA) covering the O-band is demonstrated, which is fabricated by simple and low-cost direct ultraviolet (UV) lithography.
Abstract: In this paper, a polymer/silica hybrid waveguide thermo-optic variable optical attenuator (VOA), covering the O-band, is demonstrated. The switch is fabricated by simple and low-cost direct ultraviolet (UV) lithography. The multimode interferences (MMIs) used in the Mach–Zehnder interferometer (MZI)-VOA are well optimized to realize low loss and large bandwidth. The VOA shows an extinction ratio (ER) of 18.64 dB at 1310 nm, with a power consumption of 8.72 mW. The attenuation is larger than 6.99 dB over the O-band. The rise and fall time of the VOA are 184 μs and 180 μs, respectively.

3 citations


Journal ArticleDOI
TL;DR: In this paper , a mode-selective modulator and switch to individually modulate or switch the TE11, TE12 and TE21 modes in a few-mode waveguide was proposed.
Abstract: The mode-division multiplexing (MDM) is an effective technology with huge development potential to improve the transmission capacity of optical communication system by transmitting multiple modes simultaneously in a few-mode fiber. In traditional MDM technology, the fundamental modes of multiple channels are usually modulated by external individual arranged electro-optic modulators, and then multiplexed into the few-mode fiber or waveguide by a mode multiplexer. However, this is usually limited by large device footprint and high power consumption. Here, we report a mode-selective modulator and switch to individually modulate or switch the TE11, TE12 and TE21 modes in a few-mode waveguide (FMW) to overcome this limitation. Our method is based on the graphene-polymer hybrid platform with four graphene capacitors buried in different locations of the polymer FMW by utilizing the coplanar interaction between the capacitors and spatial modes. The TE11, TE12 and TE21 modes in the FMW can be modulated and switched separately or simultaneously by applying independent gate voltage to different graphene capacitor of the device. Our study is expected to make the selective management of the spatial modes in MDM transmission systems more flexible.

3 citations


Journal ArticleDOI
TL;DR: In this article , a 1 × 1 optical switch based on the optical phase change material, Ge2Sb2Se4Te1 (GSST), was proposed for GSST-assisted silicon racetrack microring.
Abstract: In this work, we have proposed and designed a 1 × 1 optical switch based on the optical phase-change material, Ge2Sb2Se4Te1 (GSST), for GSST-assisted silicon racetrack microring. Its optical power can periodically be exchanged between the straight silicon waveguide and the GSST/Si hybrid racetrack waveguide due to the formed directional coupling structure. By changing GSST from the crystalline state to the amorphous state, the switch shifts from the ON state to the OFF state, and vice versa. With finite-difference time-domain method optimization, the proposed switch shows an extinction ratio of 18 dB at 1547.4 nm. The insert losses at the ON and OFF states are both less than 1 dB. The proposed switch unit has the potential to build an N × N switch matrix.

3 citations


Journal ArticleDOI
TL;DR: In this paper , a polarization-insensitive graphene-assisted electro-optic modulator is proposed, where the orthogonal T-shaped metal slot hybrid plasmonic waveguide allows the polarizationindependent propagation of transverse electric field mode and complex mode.
Abstract: A polarization-insensitive graphene-assisted electro-optic modulator is proposed. The orthogonal T-shaped metal slot hybrid plasmonic waveguide allows the polarization-independent propagation of transverse electric field mode and complex mode. By the introduction of dual-layer graphene on the ridge waveguide, the polarization-insensitive modulation depths of the TE mode and complex mode are 0.511 dB/µm and 0.502 dB/µm, respectively. The 3 dB bandwidth of the modulator we have proposed is about 127 GHz at the waveguide length of 20 μm. The power consumption of 72 fJ/bit promised potential graphene electro-optic modulator applications for on-chip interconnected information transfer and processing.

3 citations


Journal ArticleDOI
TL;DR: In this article , an interlayer directional coupling (DC) thermo-optic (TO) waveguide switches were designed and fabricated using functionalized epoxy-crosslinking polymers.
Abstract: In this study, interlayer directional coupling (DC) thermo-optic (TO) waveguide switches were designed and fabricated using functionalized epoxy-crosslinking polymers. Fluorinated SU-8 (FSU-8) with a photo-initiating epoxy-crosslinking network was self-synthesized as a waveguide core material. A copolymer of methyl methacrylate and glycidyl methacrylate P(MMA-co-GMA) with a thermo-initiating epoxy crosslinking structure was self-synthesized as a waveguide cladding material. Compared with commercial pure SU-8 and PMMA, FSU-8 exhibited a lower absorption loss and P(MMA-co-GMA) exhibited a higher thermal stability. Using epoxy-crosslinking functionalized polymers, the structure of the waveguides and electrode heaters were optimized, and the performance parameters of the interlayer DC TO switches were simulated. At a signal wavelength of 1550 nm, the insertion loss, extinction ratio, and power consumption of the actual interlayer devices were measured as 6.7 dB, 15.6 dB, and 9 mW, respectively. The rising and falling response times of the TO switches were obtained as 631.6 µs and 362 µs, respectively. The self-leveling ability and solvent resistance characteristic of the epoxy-crosslinking network for FSU-8 and P(MMA-co-GMA) may guarantee the realization of interlayer DC TO waveguide switches. The proposed technique will be suitable for photonic integrated waveguide chips with multilayer stacking dynamic optical information interactions.

2 citations


Journal ArticleDOI
01 Apr 2022-Polymers
TL;DR: In this paper , an ultra-broadband and compact TM-pass polarizer based on graphene-buried polymer waveguides was proposed. But the polarizers exhibit high polarization-dependent transmission imposing a TE mode cutoff while leaving the TM mode almost unaffected.
Abstract: We report an ultra-broadband and compact TM-pass polarizer based on graphene-buried polymer waveguides. The characteristic parameters of the polarizer were carefully designed and optimized. The standard microfabrication processes were employed to fabricate the device. The presented polarizers exhibit high polarization-dependent transmission imposing a TE mode cutoff while leaving the TM mode almost unaffected. We experimentally demonstrated the polarizer that has an ultra-high extinction ratio of more than 22.9 dB and 41.9 dB for the monolayer graphene film placed on the surface of core layer and buried in the center of core layer, respectively, and as low insertion loss as ~4.0 dB for the TM mode with the bandwidth over 110 nm. The presented polarizer has the advantages of high extinction ratio, ultra-broadband, low cost, and easy integration with other polymer-based planar lightwave devices.

2 citations


DOI
TL;DR: In this article , a dual-mode thermo-optic switch based on Mach-Zehnder interferometer with symmetric directional couplers is proposed and experimentally demonstrated by utilizing polymer waveguides.
Abstract: A dual-mode $2\times 2$ thermo-optic switch based on Mach-Zehnder interferometer with symmetric directional couplers is proposed and experimentally demonstrated by utilizing polymer waveguides. The present switch consists of two $2\times 2\,\,3$ -dB directional couplers, which are designed to be mode-insensitive by choosing the core separation and coupling length optimally. Meanwhile, a mode-insensitive phase shifter is employed to alter the phase of the two different modes simultaneously. With the switching power of ~9.0 mW, the measured extinction ratios for the E11 mode and E21 mode can reach to 17.5 dB and 16.4 dB, respectively, at 1550 nm, and the switching time is ~1.30 ms. The performance of the switch is also independent to the polarization state of light. Our proposed dual-mode switch with the advantages of low power-consumption can accommodate MDM system and would be applied in future large capacity communication systems.

Journal ArticleDOI
TL;DR: In this article , a 2D OPA chip is composed of four main parts: (1) tunable MQW laser array emitting light signals in the range of 1480-1600 nm wavelengths; (2) electro-optic (EO) switch array for selecting the desired signal light from the on-chip laser array; (3) EO phase-shifter array for holding a fixed phase difference for the uniform amplitude of specific optical signal; and (4) Bragg waveguide grating antenna array for controlling beamforming.
Abstract: In this work, heterogeneous integration of both two-dimensional (2D) optical phased arrays (OPAs) and on-chip laser arrays based on a silicon photonic platform is proposed. The tunable multi-quantum-well (MQW) laser arrays, active switching/shifting arrays, and grating antenna arrays are used in the OPA module to realize 2D spatial beam scanning. The 2D OPA chip is composed of four main parts: (1) tunable MQW laser array emitting light signals in the range of 1480–1600 nm wavelengths; (2) electro-optic (EO) switch array for selecting the desired signal light from the on-chip laser array; (3) EO phase-shifter array for holding a fixed phase difference for the uniform amplitude of specific optical signal; and (4) Bragg waveguide grating antenna array for controlling beamforming. By optimizing the overall performances of the 2D OPA chip, a large steering range of 88.4° × 18° is realized by tuning both the phase and the wavelength for each antenna. In contrast to the traditional thermo-optic LIDAR chip with an external light source, the overall footprint of the 2D OPA chip can be limited to 8 mm × 3 mm, and the modulation rate can be 2.5 ps. The ultra-compact 2D OPA assembling with on-chip tunable laser arrays using hybrid integration could result in the application of a high-density, high-speed, and high-precision lidar system in the future.

Journal ArticleDOI
TL;DR: In this article , a low power consumption polymer/silica hybrid thermo-optic switch based on a racetrack resonator is presented, achieving an extinction ratio of 16.83 dB while the power consumption applied is 14.69 mW.
Abstract: Large scale integration of photonics devices requires low power consumption devices. In this paper, we demonstrate a low power consumption polymer/silica hybrid thermo-optic switch based on racetrack resonator. With the high index-contrast between SU-8 core, silica buffer and PMMA cladding, a compact racetrack resonator with a small bending radius of 120 μm and a coupling length of 1765 μm is fabricated through simple and low-cost contact lithography technology. An extinction ratio of 16.83 dB is achieved while the power consumption applied is 14.69 mW. The energy efficiency of the switch is 12.07 pm/mW. The rise/fall time the switch is 174 μs/182 μs.

Journal ArticleDOI
TL;DR: In this paper , a narrow-band Bragg grating filter based on a long-range surface plasmon polariton (LRSPP) waveguide is theoretically demonstrated.
Abstract: A narrow-band Bragg grating filter based on a long-range surface plasmon polariton (LRSPP) waveguide is theoretically demonstrated. The three-dimensional Au stripe that is embedded in polymer SU-8 acts as both the waveguide and the heating electrode. With the eigen mode expansion and finite element method optimizations, the proposed filter shows a reflectivity of 0.578 and a 3 dB bandwidth of 1.1 nm. The central wavelength can be tuned from 1549.9 nm to 1544.3 nm by varying temperature from 25 °C to 75 °C, while maintaining the optical return loss at −2.5 dB. This proposed tunable filter has potential in on-chip light signal processing.

Journal ArticleDOI
TL;DR: In this paper , the authors evaluated the safety issues associated with these inhibitors and extremely low low-density lipoprotein cholesterol levels, to facilitate appropriate prescription of these new lipid-lowering drugs.
Abstract: Reduction in low-density lipoprotein cholesterol levels is the cornerstone of treatment and prevention of atherosclerotic cardiovascular diseases. Currently, high-intensity statins are being used as the first line therapy to lower low-density lipoprotein cholesterol levels, as they improve the prognosis of patients with atherosclerotic cardiovascular disease and those in high-risk groups. However, in some patients the expected reduction in cholesterol is not achieved despite aggressive treatment with statins. Moreover, some patients cannot tolerate the dosage or show poor response or compliance to statins. Therefore, combination therapies with statins and other medications should be considered. Recently, several clinical trials have shown that the use of proprotein convertase subtilisin/kexin type 9 inhibitors with or without statins and/or other lipid-lowering drugs can significantly reduce low-density lipoprotein cholesterol levels, sometimes to extremely low levels. Therefore, to facilitate appropriate prescription of these new lipid-lowering drugs, we systemically evaluated the safety issues associated with these inhibitors and extremely low low-density lipoprotein cholesterol levels.

Journal ArticleDOI
TL;DR: In this article , a three-dimensional (3D) polymer variable optical attenuator (VOA) is proposed for monolithic integration of silica and polymer-based planar lightwave circuits (PLCs).
Abstract: Low-power-consumption optical devices are crucial for large-scale photonic integrated circuits (PICs). In this paper, a three-dimensional (3D) polymer variable optical attenuator (VOA) is proposed. For monolithic integration of silica and polymer-based planar lightwave circuits (PLCs), the vertical VOA is inserted between silica-based waveguides. Optical and thermal analyses are performed through the beam propagation method (BPM) and finite-element method (FEM), respectively. A compact size of 3092 μm × 4 μm × 7 μm is achieved with a vertical multimode interference (MMI) structure. The proposed VOA shows an insertion loss (IL) of 0.58 dB and an extinction ratio (ER) of 21.18 dB. Replacing the graphene heater with an aluminum (Al) electrode, the power consumption is decreased from 29.90 mW to 21.25 mW. The rise and fall time are improved to 353.85 μs and 192.87 μs, respectively. The compact and high-performance VOA shows great potential for a variety of applications, including optical communications, integrated optics, and optical interconnections.

Journal ArticleDOI
01 Jan 2022
TL;DR: In this paper , the authors analyzed the influence of delimitation of water source protection zone on economy such as ecological migration, urban municipal pipe network construction, rural drinking water and urban water supply.
Abstract: Under the background of rapid urbanization and industrialization development, in order to satisfy the increasing demand of residents for domestic water, the establishment of water source protection zone is the most effective way to protect water resources at present. However, the influence on the social and economic development could not be ignored. The article analyzes the influence of the delimitation of water source protection zone on economy such as ecological migration, urban municipal pipe network construction, rural drinking water and urban water supply. The impact on economy like industrial enterprises, agricultural planting, livestock industry, aquaculture, tourist industry were also mentioned. The article triggers the exploration of the way to realize the coordination and sustainable development of economy, society, resources and environment

Journal ArticleDOI
01 Feb 2022-Optik
TL;DR: In this paper , a graphene optical modulator based on the tip plasmonic concept has been proposed for high-speed electro-optic modulators in optical signal processing.

Journal ArticleDOI
01 Dec 2022-Sensors
TL;DR: In this paper , an on-chip temperature sensor based on polysilicon (p-Si) waveguides is presented. But the sensor is not suitable for the field of photonic-electronic applications.
Abstract: Traditional temperature detection has limitations in terms of sensing accuracy and response time, while chip-level photoelectric sensors based on the thermo-optic effect can improve measurement sensitivity and reduce costs. This paper presents on-chip temperature sensors based on polysilicon (p-Si) waveguides. Dual-microring resonator (MRR) and asymmetric Mach–Zehnder interferometer (AMZI) sensors are demonstrated. The experimental results show that the sensitivities of the sensors based on AMZI and MRR are 86.6 pm/K and 85.7 pm/K, respectively. The temperature sensors proposed in this paper are compatible with the complementary metal-oxide-semiconductor (CMOS) fabrication technique. Benefitting from high sensitivity and a compact footprint, these sensors show great potential in the field of photonic-electronic applications.

Journal ArticleDOI
TL;DR: The Chinese Medical Journal (CMMJ) as discussed by the authors is a medical journal published by the Medical Missionary Association of China (MMA) since 1887, which was the first publication of the journal.
Abstract: The year (2022) marks the 135th anniversary of the founding of the Chinese Medical Journal. Over the past 135 years, the journal has witnessed tremendous changes in the health conditions of the Chinese people, the important role of modern medical technology in improving health, reducing diseases, and extending the life span, and the continuous improvement in medical and healthcare services and social security systems. The 135 years of the history of the Chinese Medical Journal can be divided into five stages. The first stage spans from 1887 (when the China Medical Missionary Journal [CMMJ] was first published) to March 1907 (when it was renamed the China Medical Journal). The second stage spans from 1907 to 1932 (when the China Medical Journal merged with the National Medical Journal of China). The third stage spans from 1932 to the end of 1951 (when the Editorial Board was relocated from Shanghai to Beijing). The fourth stage spans from 1952 to 1966 (when the journal was suspended). The fifth stage spans from 1973 to the present day. Soon after its founding in October 1886, the Medical Missionary Association of China decided to publish a quarterly medical journal to help unite missionary physicians working at hospitals and dispensaries across China. The journal aimed to introduce knowledge of scientific medicine and a rational system of medical practice, and to publish the latest findings in diagnosis and treatment of diseases. The journal would also include items relating to the influence of climate on health and information encouraging the private practice of medicine for study and reference by missionary physicians in China.[1] As can be seen from the early papers published in the journal, a series of serious infectious and parasitic diseases, such as smallpox, plague, cholera, leprosy, malaria, kala-azar, trachoma, schistosomiasis, hookworm, filariasis and roundworm were the most common health concern for the general population, while puerperal fever, tetanus, scarlet fever and measles particularly affected women and children.[2,3] Diseases caused by opium smoking and foot binding were also typical issues.[4] The journal published experience in surgery, anesthesia, microscopy research, and other aspects,[5] and encouraged scholars to pay attention to local surgical diagnosis and treatment,[6] as well as traditional Chinese medicine knowledge in China.[7] One of the most important tasks of the journal is to introduce the latest advances in medical science and clinical diagnosis and treatment. The journal had a column, at first named “Therapeutic Notes" and later renamed “Progress of Medical Science” or “Medical and Surgical Progress.” The column introduced the latest achievements in major British and American medical journals, such as BMJ, Lancet, and JAMA. The application of anesthetics and disinfection and antiseptic techniques represented the most important advancements in the field of surgery in the late 19th century. Almost every issue of the journal introduced related advancements, such as a speech[8] on the antiseptic treatment of wounds delivered by Joseph Lister at King's College Hospital, the introduction of iodine[9] and iodoform disinfection,[10] abdominal surgery disinfection and antisepsis techniques,[11] and others. A series of breakthroughs were also made in the prevention and control of infectious diseases. The journal included information on the etiology of infectious diseases and their classification,[12] Laveran's research on plasmodium,[13] and the application of infectious disease prevention and clinical diagnostic techniques, such as the Widal test, serum therapy,[14] and X-ray diagnosis.[15] Additionally, the journal published the establishment and development of medical and health systems, such as life and health statistics and urban health. At the second stage, the sponsors of the journal proposed that the medical and scientific characteristics of the journal should be highlighted more. In 1907, the Editorial Board of the journal published an editorial and pointed out that the original intention of the founder of the CMMJ was to attach equal importance to spreading medicine and religion. However, CMMJ was in fact still a medical journal and was well acknowledged by international peers. With the rapid development of medical technology, missionary doctors who came to China generally realized that the journal should be changed to a scientific journal rather than a vehicle for missionary propaganda. Therefore, they decided to rename the CMMJ to the China Medical Journal.[16] In fact, in order to follow the development of medical technology, missionary doctors did pay more attention to medical science and achieved certain results, for instance, Logan's research on subtropical parasitic diseases was well recognized by the international peers.[17] Another important event that occurred at the second stage was the prevention and control of a pneumonic plague in Northeast China during 1910 to 1911. The journal reported the International Plague Conference in great detail and published the speech delivered by Lien-teh Wu at the closing ceremony of the conference. Wu indicated that medical scientists had collected a lot of important information about the epidemic in the hope of providing it to the international medical community for further research and clarification of some issues that were still unclear at that time.[18] Another major event during the stage was the founding of the Chinese Medical Association in 1915. Wu introduced the founding process of this association in the China Medical Journal. Wu said a large number of ambitious students returned to China upon completing their medical education in European and American countries, and took on the mission to prevent and treat diseases domestically together with their foreign peers who came to China. However, the progress in improving the health conditions of the nation was slow, partly due to the lack of proper professional organizations or cooperation among physicians across the country. However, the spread of the pneumonic plague in Northeast China from 1910 to 1911 led to more attention being paid to health affairs and disease control. In 1915, the Chinese Medical Association was established. As one of the leaders, Wu suggested that the Chinese Medical Association and the China Medical Missionary Association would combine their efforts to ensure that medical science benefited the Chinese people.[19] In the third stage (1932–1951), to adapt to the development of institutionalization of modern medicine in China, the Chinese Medical Association merged with the China Medical Missionary Association in 1932. Additionally, the English section of the National Medical Journal of China (NMJC) and the China Medical Journal were combined into the Chinese Medical Journal, further highlighting the dominant position of Chinese scholars. The Chinese name of the journal was “”, and its volumes continued the sequence of those of the CMMJ founded in 1887. The Chinese section of the NMJC merged with The Tsinan Medical Review and its volumes continued the sequence of those of the NMJC.[20] Leprosy is an infectious disease that seriously endangers public health in China in the 1930s. In 1932, the first national conference on the prevention and control of leprosy was held by the Chinese medical community.[21] At this conference, the spread of leprosy and its multi-faceted effects on people's health, society, politics, and the economy, the government's measures on the prevention and treatment of leprosy, and the problems it faced were reviewed.[22] Following a severe flood that occurred in central China in 1931, medical staff from Beijing, Jinan, Hankou, and other locations actively participated in post-disaster epidemic prevention tasks. These tasks included setting up quarantine hospitals, conducting disinfection and sterilization, and implementing cholera vaccinations, to prevent the spread of gastrointestinal infectious diseases.[23] After the outbreak of the January 28th Incident in 1932, the Editorial Board of the journal published an article condemning the damage caused by the Japanese invading army to medical institutions and schools in Shanghai. The Editorial Board encouraged the medical professionals to join in the battlefield rescue and to control the epidemic.[24] At the beginning of the outbreak of the Chinese People's War of Resistance against Japanese Aggression, the journal continued its publication in Shanghai, Chengdu, and Washington D.C. to maintain academic continuity.[25] Hengbi Zhu reviewed the difficulty of medical education in pursuing its development during this war. He pointed out that 11 medical schools (the Central University Medical School, Tung-chi University Medical School, Cheeloo University Medical School, Hsiang-Ya Medical School, the Chung Cheng Medical College, the Shanghai National Medical College, The Kiangsu Medical College, the Army Medical School, the Chekiang Provincial Medical School, the Medical College of the Peiping University, and the Shantung Provincial Medical School) were relocated to inland areas because of the invasion of the Japanese army. These medical schools were still striving to train medical students under the poor conditions of school buildings, faculty resources, and equipment.[26] After the founding of the People's Republic of China, the Editorial Board of the journal was relocated to Beijing in 1951. In the fourth stage (1952–1966), since the founding of the People's Republic of China, the country has witnessed a rapid development of medical and health undertakings and the gradual improvement of public health. In 1953, Naiquan Gong stated in an article that, within only a few years of the founding of the People's Republic of China, the national medical and health systems had been established. Furthermore, public health facilities had been gradually improved, healthcare security systems had been formed, training programs for medical professionals had been developed on a large scale, and environmental sanitation had been improved greatly. Remarkable achievements had also been made in the prevention and control of infectious diseases, hygiene of industrial and mining enterprises, and the reduction of maternal and infant mortality, among others.[27] Chuankui Hu et al introduced the achievements made by China in the prevention and control of sexually transmitted diseases after 1949.[28] Huilan Zhong et al stated the value of the complement fixation test in the diagnosis of schistosomiasis,[29] and Zongchang Hou et al described the achievements made in the prevention and control of parasitic diseases.[30] In 1957, Feifan Tang, Xiaolou Zhang, Yuantong Huang, and Keqian Wang published a study on the pathogen of trachoma.[31] This study represented an important contribution made by Chinese medical scientists to the field of pathogen biology. At the 10th anniversary of the founding of the People's Republic of China in 1959, Dequan Li[32] introduced the achievements made by China in public health. Additionally, Kahti Lin, Yingkun Feng, and Cheng-Hsiang Hu et al described the research progress of obstetrics and gynecology,[33] neuroscience,[34] and pathology,[35] respectively. In 1965, Yingkai Wu introduced a series of important results[36] achieved in the field of surgery regarding the treatment of severe burns, replanting of severed fingers, integration of traditional Chinese medicine and Western medicine, cardiovascular surgery, and others. Futang Chu introduced the achievements made in the prevention of infectious diseases in children.[37] Qi He summarized the experience gained in epidemiological research and the eradication of malaria.[38] With regard to research on combined traditional Chinese and Western medicine, Ankun Kuang made remarkable achievements in research on the pharmacological mechanism of the traditional Chinese medicine Liuwei Dihuang decoction.[39] Improving rural health services constitutes the basis for improving the overall health status of the public. With social and economic development, the Chinese government have focused on how to improve health work in rural areas. In 1965, the Editorial Board of the journal published an editorial that emphasized the need for the medical community to pay more attention to health conditions of farmers.[40] Zikuan Zhang introduced the measures taken by China to gradually improve the medical service level in rural areas. These measures included organizing the Chinese medical community to prevent and control schistosomiasis, dispatching traveling dispensaries to diagnose and treat diseases for farmers, and training rural healthcare workers.[41] In 1966, the journal was renamed China's Medicine and continued its publication, but it was suspended. In the fifth stage (from 1973 when the journal was republished to the present day), the journal gradually resumed normal publication and its international influence is growing. In 1972, the journal resumed its publication with the approval of the State Council of the People's Republic of China with the efforts of the medical community. After republication of the journal in 1973, it published a series of papers that reflected the progress of contemporary medical research, such as replanting of amputated limbs,[42] the treatment of acute abdominal conditions through a combination of traditional Chinese and Western medicine,[43] and acupuncture and anesthesia.[44] Following a reform and opening-up, the journal was restored from a bimonthly to monthly publication in 1979. Journal publication expanded to semi-monthly in 2005 to meet the needs for the development of medical and health services in China. With the transformation of the disease spectrum, infectious and parasitic diseases that previously endangered public health have been effectively controlled. Linhua Tang summarized the major achievements made by China in malaria control over the past 50 years. With the participation of the primary health care networks and the community, large-scale malaria control has been conducted and has been remarkably successful. By the end of 1998, there were 31,300 malaria cases in China, with an incidence rate of 0.25/10,000, which showed a decrease of 99% compared with that in 1950.[45] Cardiovascular and cerebrovascular diseases, malignant tumors, and mental illness have become major disease burdens. To reduce the harm of chronic diseases, Chinese medical scientists have carried out successful research on the risk factors for chronic diseases and the discovery of traditional medicine for cancer treatment. Xinzhi Weng reported a national epidemiological survey on smoking,[46] and Xiaojun Huang reviewed investigation by Chinese scholars on the study of traditional Chinese medicine for leukemia treatment and the experience that they gained.[47] Additionally, Longde Wang introduced the initial establishment of a stroke management model in China.[48] With regard to the prevention and control of chronic infectious diseases, Hong Shang introduced the experience gained by China in the prevention and control of acquired immune deficiency syndrome over the past 30 years.[49] Yihua Zhou described the progress of eradicating chronic hepatitis B in children by preventing mother-child transmission of this disease.[50] Since the beginning of the 21st century, emerging infectious diseases have become a major risk, endangering public health. After the outbreak of severe acute respiratory syndrome in 2003, our medical community made a swift response. Nanshan Zhong et al compiled an expert consensus on the management of severe acute respiratory syndrome.[51] Since the outbreak of COVID-19 in 2019, medical scientists have performed in-depth research on the clinical characteristics of patients, the time and risk factors of viral clearance, developed experts’ consensus, and have made important progress.[52–54] Throughout the 135-year history of the Chinese Medical Journal, the journal has not only witnessed tremendous changes in the health status of the Chinese people, but has also shown important contributions made by Chinese medical scientists in studying disease and health issues. With reflection on the past, the development of modern medicine in China has evolved, from the introduction of Western medicine to the present day, when China also has assumed its responsibility for the global health cause and played a vital role in solving global health concerns. History has proven that China can creatively respond to increasing health challenges with the aid of leading medical and health knowledge. Additionally, China can propose relevant “Chinese solutions” for effectively responding to global health challenges on the basis of achieving the goal of the Healthy China initiative. Conflicts of interest None.

Journal ArticleDOI
TL;DR: In this article , a coupled mode theory was built to explain and alleviate the phenomenon of resonance splitting in a dual-concentric ring resonator and a racetrack resonator, and the experimental results proved that the asymmetry of resonance split can be tuned by adjusting the distance between the inner-ring and outer-ring, as well as the waveguide width.
Abstract: Micro-ring resonator (MRR) is a key element in integrated optics. The mutual-coupling in dual-concentric MRR has great influence on the resonance output. In this work, high-Q silicon dual-concentric MRR and racetrack resonator have been investigated by the coupled mode theory. The theoretical model is built to explain and alleviate the phenomenon of resonance splitting. CMOS fabrication is adopted for the preparation of dual-concentric MRR and racetrack resonators. The highest Q-factors of dual-concentric MRR and racetrack resonator are measured to be ∼9.00 × 104 at 1530.783 nm and ∼7.32 × 104 at 1536.596 nm, respectively. The notch depth improvement over 20 dB has been demonstrated on the 5-μm-radius double-ring structure. The experimental results prove that the asymmetry of resonance splitting can be tuned by adjusting the distance between the inner-ring and outer-ring, as well as the waveguide width. The proposed work has potentials in the design and optimization of dual-concentric ring resonators.