Preliminary assessment of portable sleep monitoring for diagnosis of obstructive sleep apnea in children.

OBJECTIVE: By observing the differences in sleep parameters between portable sleep monitoring (PM) and polysomnography (PSG) in children, we aimed to investigate the diagnostic value and feasibility of PM in children with suspected obstructive sleep apnea (OSA). STUDY DESIGN: This prospective study enrolled consecutive children (aged 3-14 years) with suspected OSA in Shenzhen Children's Hospital. They had PSG and PM in the sleep laboratory. Clinical parameters of the two sleep monitoring methods were compared. RESULTS: A total of 58 children participated. They were classified into two groups according to age: 28 children aged 3 to 5 years and 30 children aged 6 to 14 years. No significant differences were observed in apnea-hypopnea index (AHI), lowest oxygen saturation (LSaO2), and mean oxygen saturation (MSaO2) between PM and PSG, but the sleep efficiency with PM was significantly higher (3-5 years age: 92.2 ± 11.3% vs 85.2 ± 14.3%, 6-14 years age: 93.2 ± 14.5% vs 84.8 ± 16.3%, both P < 0.05) than the sleep efficiency with PSG. Pearson correlation analysis indicated a strong correlation between AHI, LSaO2, MSaO2, and sleep efficiency measured by PSG and PM. Receiver operating characteristic curve (ROC) analysis showed that PM was a reliable diagnostic tool for OSA. PM has high sensitivity (3-5 years age: 95.8%, 6-14 years age: 96.3%) and low specificity (3-5 years age: 25.0%, 6-14 years age: 33.3%) for OSA in children. Thus, there is a low rate of missed diagnoses, but there is some inaccuracy in excluding children who do not have OSA. CONCLUSION: The results showed that PM has a good correlation with the various parameters of PSG. PM may be a reliable tool for diagnosing moderate and severe OSA in children, especially those who cannot cooperate with PSG or who have limited access to PSG.

The role of adjuvant systemic corticosteroid in pediatric retropharyngeal and parapharyngeal abscess.

OBJECTIVES: To evaluate the potential benefits of systemic corticosteroids as an adjuvant treatment for pediatric retropharyngeal abscess (RPA) and parapharyngeal abscess (PPA). METHODS: We retrospectively reviewed medical records of patients diagnosed with RPA and PPA who were admitted to Shenzhen Children's Hospital between January 2010 and January 2023. Data on demographic characteristics, clinical presentation, physical examination, laboratory data, use of corticosteroids, management, duration of hospital stay, need for surgical drainage, and complications were collected. Patients were divided into two groups: non-corticosteroid group (antibiotic only) and corticosteroid group (corticosteroid and antibiotic). RESULTS: A total of 111 patients were enrolled. There were 51 cases in non-corticosteroid group and 60 cases in corticosteroid group (10 cases received methylprednisolone and 50 cases received dexamethasone). There was no significant difference in sex, age, location of abscess, size of abscess and laboratory parameters at admission and discharge between the two groups. The surgical drainage rate was significantly lower in the corticosteroid group than in the non-corticosteroid group (p = 0.008). The hospital duration was also shorter in the corticosteroid group than in the non-corticosteroid group (p = 0.026). The hospitalization cost was significantly lower in the corticosteroid group than in the non-corticosteroid group (p = 0.000). CONCLUSION: The use of systemic corticosteroids along with antibiotics in children with RPA and PPA may reduce the need for surgical drainage, shorten hospital duration, and decrease hospitalization cost. Further studies are needed to confirm these findings and determine the optimal timing, duration, and route of administration of corticosteroids.

External auditory canal cholesteatoma in children: clinical manifestations.

PURPOSE: The purpose of this study was to explore the characteristics of external auditory canal cholesteatoma (EACC) among children and to describe its radiological findings on high-resolution computed tomography (CT) of the temporal bone in order to improve the diagnostic accuracy of primary EACC. METHODS: The clinical records and CT imaging features of 44 patients who were diagnosed with EACC between January 2017 and May 2022 at Shenzhen Children's Hospital were retrospectively reviewed. Clinical features, including external auditory canal wall findings, hearing damage, symptoms and physical examination findings, were analysed against the level of lesion involvement. The correlation between different types of EACC and the incidence of different clinical symptoms was analysed, and the degree of hearing impairment and the rate of bone wall destruction were examined using CT. RESULTS: The mean age at EACC onset was 9.02 ± 3.15 years, and the mean age at onset for EACC involving the right ear was older than that of EACC involving the left ear (P < 0.05). There were 44 patients (46 ears), including 10 ears with type I EACC, 23 ears with type II EACC, and 13 ears with type III EACC. Conductive hearing loss was the main type of hearing impairment observed among EACC patients. There were differences in types I, II and III EACC in terms of hearing impairment; specifically, there was a significant difference in moderate hearing impairment between type II and type III EACC patients (P < 0.05). The four most common symptoms were otorrhea, otalgia, itching and bleeding. The incidence of itching symptoms was greater in type I EACC than the incidence of otorrhea, and the incidence of otorrhea symptoms in type II and type III EACC was significantly greater than that in type I EACC(P < 0.05). There were no significant differences in the fracture rates of the anterior, posterior, superior or inferior walls of the external auditory canal within or between type II and type III EACC patients (P > 0.05). The failure rate of scute damage was significantly higher in type III EACC patients than in type II EACC patients (P < 0.05). CONCLUSION: The presence of otorrhea and hearing loss as well as the identification of granulation tissue during otoscopy suggest the need for a temporal bone CT scan. This imaging modality can aid in the early detection and accurate classification of EACC, thereby guiding the selection of appropriate surgical interventions and greatly assisting in preventing further progression of hearing impairment.

Study on Mechanical and Acoustic Emission Characteristics of Backfill-Rock Instability under Different Stress Conditions.

Unveiling the mechanical properties and damage mechanism of the complex composite structure, comprising backfill and surrounding rock, is crucial for ensuring the safe development of the downward-approach backfill mining method. This work conducts biaxial compression tests on backfill-rock under various loading conditions. The damage process is analyzed using DIC and acoustic emission (AE) techniques, while the distribution of AE events at different loading stages is explored. Additionally, the dominant failure forms of specimens are studied through multifractal analysis. The damage evolution law of backfill-rock combinations is elucidated. The results indicate that DIC and AE provide consistent descriptions of specimen damage, and the damage evolution of backfill-rock composite specimens varies notably under different loading conditions, offering valuable insights for engineering site safety protection.

Multimodal Ultrasound Radiomic Technology for Diagnosing Benign and Malignant Thyroid Nodules of Ti-Rads 4-5: A Multicenter Study.

This study included 468 patients and aimed to use multimodal ultrasound radiomic technology to predict the malignancy of TI-RADS 4-5 thyroid nodules. First, radiomic features are extracted from conventional two-dimensional ultrasound (transverse ultrasound and longitudinal ultrasound), strain elastography (SE), and shear-wave-imaging (SWE) images. Next, the least absolute shrinkage and selection operator (LASSO) is used to screen out features related to malignant tumors. Finally, a support vector machine (SVM) is used to predict the malignancy of thyroid nodules. The Shapley additive explanation (SHAP) method was used to intuitively analyze the specific contributions of radiomic features to the model's prediction. Our proposed model has AUCs of 0.971 and 0.856 in the training and testing sets, respectively. Our proposed model has a higher prediction accuracy compared to those of models with other modal combinations. In the external validation set, the AUC of the model is 0.779, which proves that the model has good generalization ability. Moreover, SHAP analysis was used to examine the overall impacts of various radiomic features on model predictions and local explanations for individual patient evaluations. Our proposed multimodal ultrasound radiomic model can effectively integrate different data collected using multiple ultrasound sensors and has good diagnostic performance for TI-RADS 4-5 thyroid nodules.

Maternal anaemia prevention and control in China: A policy review.

Maternal anaemia is a major public health problem. Developing maternal anaemia prevention and control policies is an important prerequisite for carrying out evidence-based interventions. This article reviews maternal anaemia prevention and control policies in China, identifies gaps, and provides references for other countries. We examined policies concerning maternal nutrition and other related literature in China, identified through key databases and government websites, and conducted a narrative review of the relevant documentations guided by the Smith Policy-Implementing-Process framework. A total of 65 articles and documents were identified for analysis. We found that Chinese government has committed to reducing maternal anaemia at the policy level, with established objectives and a clear time frame. However, most of policies were not accompanied by operational guidelines, standardized interventions, and vigorous monitoring and evaluation mechanisms, and 85% of the policies don't have quantifiable objectives on anaemia. Maternal anaemia prevention and control services offered in clinical settings were primarily nutrition education and anaemia screening. Population-based interventions such as iron fortification have yet to be scaled up. Furthermore, medical insurance schemes in some regions do not cover anaemia prevention and treatment, and in other regions that offer coverage, the reimbursement rate is low. The number and capacity of health professionals is also limited. Policy changes should focus on the integration of evidence-based interventions into routine antenatal care services and public health service packages, standardization of dosages and provision of iron supplementation, streamline of reimbursement for outpatient expenses, and capacity building of health professionals.

Tetrahydroberberrubine retards heart aging in mice by promoting PHB2-mediated mitophagy.

Heart aging is characterized by left ventricular hypertrophy and diastolic dysfunction, which in turn induces a variety of cardiovascular diseases. There is still no therapeutic drug to ameliorate cardiac abnormities in heart aging. In this study we investigated the protective effects of berberine (BBR) and its derivative tetrahydroberberrubine (THBru) against heart aging process. Heart aging was induced in mice by injection of D-galactose (D-gal, 120 mg · kg-1 · d-1, sc.) for 12 weeks. Meanwhile the mice were orally treated with berberine (50 mg · kg-1 · d-1) or THBru (25, 50 mg · kg-1 · d-1) for 12 weeks. We showed that BBR and THBru treatment significantly mitigated diastolic dysfunction and cardiac remodeling in D-gal-induced aging mice. Furthermore, treatment with BBR (40 µM) and THBru (20, 40 µM) inhibited D-gal-induced senescence in primary neonatal mouse cardiomyocytes in vitro. Overall, THBru exhibited higher efficacy than BBR at the same dose. We found that the levels of mitophagy were significantly decreased during the aging process in vivo and in vitro, THBru and BBR promoted mitophagy with different potencies. We demonstrated that the mitophagy-inducing effects of THBru resulted from increased mRNA stability of prohibitin 2 (PHB2), a pivotal factor during mitophagy, thereby upregulating PHB2 protein expression. Knockdown of PHB2 effectively reversed the antisenescence effects of THBru in D-gal-treated cardiomyocytes. On the contrary, overexpression of PHB2 promoted mitophagy and retarded cardiomyocyte senescence, as THBru did. In conclusion, this study identifies THBru as a potent antiaging medicine that induces PHB2-mediated mitophagy and suggests its clinical application prospects.

Effects of drug-induced sleep endoscopy in children with conventional obstructive sleep apnea-hypopnea syndrome: a systematic review and meta-analysis.

PURPOSE: This study aimed to conduct a meta-analysis and systematic review of drug-induced sleep endoscopy (DISE) in pediatric conventional obstructive sleep apnea-hypopnea syndrome (OSAHS) without previous upper airway surgery, or comorbidity, to evaluate the change in treatment strategies and to identify obstructive sites observed during DISE. This study aimed to explore the role of DISE in the management of pediatric conventional OSAHS. METHODS: A comprehensive search was conducted using both computerized and manual methods to retrieve relevant case studies on DISE-guided treatment of pediatric conventional OSAHS from databases including PubMed, EMBASE, Cochrane Library, Web of Science, CNKI, WF, and VIP database. The search period extended from database inception to January 2023. Strict inclusion and exclusion criteria were applied to select relevant literature, and data extraction was performed accordingly. Meta-analysis was conducted using the Stata 16.0 software. RESULTS: A total of 761 patients from four studies were included in the meta-analysis. All pediatric patients had no history of upper airway surgery, craniofacial abnormalities, or syndromes other than OSAHS. The quality assessment revealed that the included studies were of low methodological quality and consisted of non-randomized case studies. Meta-analysis results indicated that in pediatric patients with OSAHS, the obstruction rates observed during DISE were as follows: nasopharyngeal (adenoid) obstruction 93%, soft palate obstruction 35%, oropharyngeal (tonsil) obstruction 76%, tongue base obstruction 32%, supraglottic obstruction 31%, and multi-level obstruction 60%. DISE led to a change in the conventional surgical approach in 45% (95% CI: 29-60%) of patients with OSAHS, providing individualized treatment plans. Postoperative symptoms and sleep-related parameters improved significantly compared to preoperative values, with DISE findings possibly enhancing surgical success rates and potentially avoiding unnecessary procedures. CONCLUSION: In some cases, DISE may potentially lead to alterations in conventional surgical approaches for children with OSAHS who had no history of upper airway surgery, craniofacial abnormalities, or other syndromes.. The results of our meta-analysis were in favor of DISE-directed approach for pediatric conventional OSAHS. However, further high-quality randomized controlled trials (RCTs) are warranted in future research to investigate the role of DISE in the management of pediatric OSAHS.

Microwave Absolute Distance Measurement Method with Ten-Micron-Level Accuracy and Meter-Level Range Based on Frequency Domain Interferometry.

A microwave absolute distance measurement method with ten-micron-level accuracy and meter-level range based on frequency domain interferometry is proposed and experimentally demonstrated for the first time. Theoretical analysis indicates that an interference phenomenon occurs instantaneously in the frequency domain when combining two homologous broad-spectrum microwave beams with different paths, and the absolute value of the distance difference between the two paths is only inversely proportional to the period of frequency domain interference fringes. The proof-of-principle experiments were performed to prove that the proposed method can achieve absolute distance measurement in the X-band with standard deviations of 15 µm, 17 µm, and 26 µm and within ranges of 1.69 m, 2.69 m, and 3.75 m. Additionally, a displacement resolution of 100 microns was realized. The multi-target recognition performance was also verified in principle. Furthermore, at the expense of a slight decrease in ranging accuracy, a fast distance measurement with the single measurement time of 20 µs was achieved by using a digitizer combined with a Fourier transform analyzer. Compared with the current microwave precision ranging technologies, the proposed method not only has the advantages of high precision, large range, and rapid measurement capability, but the required components are also easily obtainable commercial devices. The proposed method also has better complex engineering applicability, because the ten-micron-level ranging accuracy is achievable only by using a simple Fourier transform without any phase estimation algorithm, which greatly reduces the requirement for signal-to-noise ratio.

BIRC5 Inhibition Is Associated with Pyroptotic Cell Death via Caspase3-GSDME Pathway in Lung Adenocarcinoma Cells.

Lung adenocarcinoma (LUAD) is a prevalent type of thoracic cancer with a poor prognosis and high mortality rate. However, the exact pathogenesis of this cancer is still not fully understood. One potential factor that can contribute to the development of lung adenocarcinoma is DNA methylation, which can cause changes in chromosome structure and potentially lead to the formation of tumors. The baculoviral IAP repeat containing the 5 (BIRC5) gene encodes the Survivin protein, which is a multifunctional gene involved in cell proliferation, migration, and invasion of tumor cells. This gene is elevated in various solid tumors, but its specific role and mechanism in lung adenocarcinoma are not well-known. To identify the potential biomarkers associated with lung adenocarcinoma, we screened the methylation-regulated differentially expressed genes (MeDEGs) of LUAD via bioinformatics analysis. Gene ontology (GO) process and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were applied to investigate the biological function and pathway of MeDEGs. A protein-protein interaction (PPI) network was employed to explore the key module and screen hub genes. We screened out eight hub genes whose products are aberrantly expressed, and whose DNA methylation modification level is significantly changed in lung adenocarcinoma. BIRC5 is a bona fide marker which was remarkably up-regulated in tumor tissues. Flow cytometry analysis, lactate dehydrogenase release (LDH) assay and Micro-PET imaging were performed in A549 cells and a mouse xenograft tumor to explore the function of BIRC5 in cell death of lung adenocarcinoma. We found that BIRC5 was up-regulated and related to a high mortality rate in lung adenocarcinoma patients. Mechanically, the knockdown of BIRC5 inhibited the proliferation of A549 cells and induced pyroptosis via caspase3/GSDME signaling. Our findings have unraveled that BIRC5 holds promise as a novel biomarker and therapeutic target for lung adenocarcinoma. Additionally, we have discovered a novel pathway in which BIRC5 inhibition can induce pyroptosis through the caspase3-GSDME pathway in lung adenocarcinoma cells.

Characteristics and Treatment of Pediatric Tracheobronchial Foreign Bodies: A Retrospective Analysis of 715 Cases.

BACKGROUND This study aimed to analyze the clinical characteristics of tracheobronchial foreign bodies in children in Shenzhen and to explore the diagnosis and treatment methods for special cases. MATERIAL AND METHODS This study included a total of 715 children who were diagnosed with tracheobronchial foreign bodies at Shenzhen Children's Hospital between October 2016 and October 2021. Data on sex, age, inducement, symptoms, foreign body type, foreign body location, foreign body retention time, foreign body history, and complications were recorded and analyzed. RESULTS Tracheal foreign bodies were found to occur primarily in children aged 0-2 years (90.6%). The overall incidence rates were 69.1% and 30.9% in boys and girls, respectively. Among them, 42.5% of the foreign bodies were detected in the left bronchus and 45.6% in the right bronchus. Inducements included playing while eating (n=398, 55.7%) and also crying (n=209, 29.2%). Operations were performed on 710 (99.3%) children, including 80 (11.2%) immediate surgeries and 2 tracheotomies. One child had no vital signs upon admission and died after emergency foreign body removal. All of the other children who underwent surgery recovered well postoperatively. CONCLUSIONS This study presents the characteristics and methods of diagnosis and treatment of tracheobronchial foreign bodies in pediatric patients in Shenzhen. Tracheobronchial foreign bodies are a major cause of accidental injury in infants and young children. In critical cases, airways should be immediately and rapidly cleared with multidisciplinary collaboration. In addition, public safety awareness should be strengthened, particularly among parents, teachers, and other child caregivers, to reduce and prevent instances of tracheobronchial foreign body accidents in children.

Gbit/s secure key generation and distribution based on the phase noise of an amplified spontaneous emission source.

In this paper, a secure key generation and distribution scheme based on the phase noise of an amplified spontaneous emission source is proposed and experimentally verified. A giant key generator that contains two distribution arms is used to generate a specific beat dependent on the path length difference of the arms. Through the method of balanced subtraction of the local signals, the effect of the intensity noise has been mainly excluded, and the two legal users obtain the consistent differential signal that depended on the phase noise. Experiment results show that the correlation coefficient of the key signals reaches to about 0.89, and the bit generation rate of the scheme achieves to 3.06 Gbit/s under a length of 20 km standard single-mode optical fiber route, as the bit error rate stays under 0.02%. Moreover, the converted digital key stream has passed the NIST statistical test suite, which means that the scheme is inherently random in the statistical sense. With the excellent performance mentioned above, the proposed scheme provides a simple and efficient solution for the method of one-time pad.

Management of oesophageal foreign bodies in children: a 10-year retrospective analysis from a tertiary care center.

OBJECTIVE: Oesophageal foreign bodies (EFBs) are a common emergency issue in paediatrics, and few studies have revealed its clinical features and treatment methods. We conducted this retrospective study to provide our 10-year clinical evidence for the diagnosis and treatment of EFB and reduce the incidence of complications. METHODS: We retrospectively reviewed all paediatric cases diagnosed with EFB from January 2012 to December 2021 at Shenzhen Children's Hospital. The age and sex of the patients, types of foreign bodies (FBs), preoperative examination, location and duration of FB impaction, clinical symptoms, surgical methods, therapeutic effects and complications were analysed. RESULTS: Among the 1355 cases, 759 were boys and 596 were girls, with a median age of 2.9 years (4 months to 16 years). The shortest FB lodged time was 1 hour, while the longest time was 3 months. The types of foreign bodies included coins and blunt objects (812,59.9%), bones and sharp objects (278,20.5%), button batteries (86,6.3%), food impactions (84,6.2%), toys (51,3.8%) and plastic objects (44,3.2%). A total of 720 of 812 cases impacted by coins and blunt subjects were successfully treated with a Foley catheter without any complications. A total of 558 patients underwent rigid oesophageal endoscopy under general anaesthesia, and foreign bodies were successfully removed in 525 cases. No FB was found in 33 cases, and FBs pushed into the lower digestive tract during operation in 5 cases. Oesophageal injury was found in 130 cases (23.3%). Our study showed that the age of the patient, time of foreign body incarceration, type of foreign body, location of the lodged foreign body, and fever or cough were risk factors leading to oesophageal foreign body complications, and the differences were statistically significant (P < 0.05). CONCLUSION: Children with EFB have a risk of complications, especially if the FB is a button battery. The appropriate surgical method should be selected through the analysis of the clinical characteristics of the foreign body in the oesophagus and the risk factors for complications to reduce the incidence of complications. Health education and effective care are the keys to the prevention of EFB.

Secure key distribution based on bidirectional Michelson interferometers.

A scheme based on bidirectional Michelson interferometers to distribute secret keys through the phase of light wave is proposed and demonstrated. The structure uses two optical cable transmission schemes, lasers of short coherent length, random phase drift, polarization random disturbance, and vibration positioning technology to ensure the safe transmission of the secret key. The feasibility of 80 km secret key transmission is verified by experiments. When the secret key is transmitted at the frequency of 200 kHz, the bit error rate is less than 0.3%, and the disturbance positioning accuracy is within $\pm {100}\;{\rm m}$.

Superabsorbent polymer balls as foreign bodies in the nasal cavities of children: our clinical experience.

OBJECTIVE: To summarize the clinical diagnosis and treatment of superabsorbent polymer balls as nasal foreign bodies in children. METHODS: We retrospectively analysed the clinical data concerning 12 cases of superabsorbent polymer balls as nasal foreign bodies in children and summarized the corresponding clinical features, methods of diagnoses and treatment, and prognoses. RESULTS: Twelve children with superabsorbent polymer balls as foreign bodies in their nasal cavities presented with relatively severe symptoms, such as congestion, runny nose, and nasal swelling. When such foreign bodies stay in the nasal cavity for a prolonged period, patients may suffer from general discomfort, such as agitation, poor appetite and high fever. Most of the children had to undergo nasal endoscopy under general anaesthesia to have the foreign bodies completely removed. An intraoperative examination revealed significant mucosal injury within the nasal cavity. With regular follow-up visits and adequate interventions, all the patients recovered. CONCLUSION: The longer superabsorbent polymer balls remain in the nasal cavity, the more damaged the nasal mucosa will be. It is challenging to remove such foreign bodies in the outpatient setting. Transnasal endoscopy under general anaesthesia appears to be safer and more effective in such cases. Since the nasal mucosa is injured to varying degrees, postoperative follow-up and treatment are equally important for preventing the occurrence of complications.

A first-aid fast track channel for rescuing critically ill children with airway foreign bodies: our clinical experience.

OBJECTIVE: To explore the role of a first-aid fast track channel in rescuing children with airway foreign bodies and to analyse and summarize the experience and lessons of the first-aid fast track channel in rescuing airway foreign bodies from patients in critical condition. METHODS: We retrospectively reviewed the medical records of children with airway foreign bodies rescued by first-aid fast track channels admitted to our hospital from January 2017 to December 2020. The corresponding clinical features, treatments, and prognoses were summarized. RESULTS: Clinical data from 21 cases of first-aid fast track channel patients were retrospectively collected, including 12 males and 9 females aged 9-18 months. Cough was the most frequently exhibited symptom (100.0%), followed by III inspiratory dyspnoea (71.4%). Regarding the location of foreign bodies, 5 cases (23.8%) had glottic foreign bodies, 10 cases (47.6%) had tracheal foreign bodies, and 6 cases (28.6%) had bilateral bronchial foreign bodies. The most common type of FB was organic. FB removal was performed by rigid bronchoscopy in every case, and there were no complications of laryngeal oedema, subcutaneous emphysema, or pneumothorax. No tracheotomy was performed in any of the children. CONCLUSION: The first-aid fast track channel for airway foreign bodies saves a valuable time for rescue, highlights the purpose of rescue, improves the success rate of rescue and the quality of life of children, and is of great value for the treatment of critical tracheal foreign bodies. It is necessary to regularly summarize the experience of the first-aid fast track channel of airway foreign bodies and further optimize the setting of the first-aid fast track channel.

Distributed fiber-optic sensor for location based on polarization-stabilized dual-Mach-Zehnder interferometer.

A novel distributed fiber-optic sensor is proposed and demonstrated, in which two Mach-Zehnder interferometers are used to detect the interference signals with different wavelengths, and one 3 × 3 coupler is deployed to demodulate the time-varying phase change caused by vibration. The novel dual Mach-Zehnder interferometer (DMZI) is composed of two wavelength division multiplexers. Then, a time delay estimation algorithm is designed to construct two related signals using the phase difference, and the two constructed signals are used to obtain vibration position through cross-correlation. Experimental results show that the sensing distance can reach 100 km and the location error is within ±25 m.

On-chip high-sensitivity photonic temperature sensor based on a GaAs microresonator.

We demonstrate an on-chip high-sensitivity photonic temperature sensor based on a GaAs microdisk resonator. Based on the large thermo-optic coefficient of GaAs, a temperature sensitivity of 0.142 nm/K with a measurement resolution of 10 mK and low input optical power of only 0.5 µW was achieved. It exhibits great potential for chip-scale biological research and integrated photonic signal processing.

Comparison of null-subcarriers reservation and adaptive notch filter for narrowband interference cancellation in intra-data center interconnect with DMT signal transmission.

In this paper, we experimentally compare the performance of two different narrowband interference suppression schemes in 120 Gb/s intensity modulation and direct detection (IM/DD) system with discrete multi-tone (DMT) signal transmission for intra-data center interconnect (Intra-DCI). Digital pre-equalization and DFT-spread techniques are applied for system bandwidth limitation induced signal distortion compensation and signal peak to average power ratio (PAPR) reduction, respectively. Null-subcarriers reservation (NSR) and adaptive notch filter (ANF) techniques are compared during the suppression of digital-to-analog convertor (DAC) clock leakage induced narrowband interference. 1.2 dB and 1.8 dB DMT receiver sensitivity improvements can be achieved at a bit-error rate of 3.8 × 10-3 in optical back-to-back (OBTB) transmission when optimized NSR and ANF schemes are applied for narrowband interference cancellation, respectively. After 2-km single mode fiber (SMF) transmission, the required received optical power (ROP) of DMT signal with optimized NSR and ANF for narrowband interference cancellation at BER of 3.8 × 10-3 are -6.5 dBm and -7.1 dBm, respectively. Obviously, ANF outperforms NSR scheme in narrowband interference cancellation for DMT system.

Silica-microsphere-cavity-based microwave photonic notch filter with ultra-narrow bandwidth and high peak rejection.

We propose and experimentally demonstrate a microwave photonic (MWP) notch filter based on a silica microsphere cavity. By using a high-Q-factor (∼1e7) cavity with a diameter of 132 um, the filter bandwidth can be easily decreased to 15 MHz in terms of simple fabrication and flexible coupling. Then we use the advanced modulation technique based on a dual parallel Mach-Zehnder modulator to further improve peak rejection (PR). The experimental results show that the MWP notch filter with its PR beyond 55 dB and frequency tunability range over 8 GHz has been achieved in combination with double-sideband modulation. To the best of our knowledge, this is a record for PR and bandwidth considered simultaneously for an MWP filter based on silica microcavities. Thus, the proposed MWP filter will be useful in the fields of microwave photonic signal processing, radar systems, etc.