Fully adiabatic polarization rotator-splitter based on thin-film lithium niobate platform.

A Polarization Rotator-Splitter (PRS) based on thin-film lithium niobate (TFLN) is demonstrated in this work. The PRS consists of a partially etched polarization rotating taper and an adiabatic coupler, which enables the input TE0 and TM0 to be output as TE0 from two ports, respectively. The fabricated PRS using standard i-line photolithography achieved large polarization extinction ratios (PERs) of > 20 dB across the whole C-band. Excellent polarization characteristics are maintained when the width is changed by ±150 nm. The on-chip insertion losses of TE0 and TM0 are less than 1.5 dB and 1 dB, respectively.

Contemplating the necessity of surgical treatment for posterior lenticonus: a case report.

BACKGROUND: Posterior lenticonus is an uncommon congenital abnormality that causes a progressive, localized spherical or conical bulging of the posterior capsular membrane, resulting in an abnormal shape of the lens. CASE PRESENTATION: A 13-year-old girl presented with ametropia in both eyes. After mydriasis, examination revealed an oval bubble-shaped alteration with a distinct boundary above the temporal region on the center of the posterior capsule of her left lens. The subcortical region surrounding the alteration appeared feathery and turbid. The patient had no history of trauma or family history of visual impairment. Systemic investigations were normal. A thorough eye examination was performed, which included optometry, ultrasound biomicroscopy, ocular B-Scan, and anterior segment optical coherence, to assess the disease. The patient was diagnosed with posterior lenticonus in the left eye, as well as ametropia and anisometropia in both eyes. Conservative treatment was initiated since the patient's current best corrected visual acuity was good, and regular monitoring of the condition's progression was scheduled. CONCLUSIONS: This case report presents a rare instance of posterior lenticonus. The findings of this report raise new considerations regarding the necessity of surgical intervention for this condition.

Pathological characteristics and immune microenvironment of SMARCA4-deficient undifferentiated uterine sarcoma.

SMARCA4-deficient undifferentiated uterine sarcoma (SDUS) is a highly invasive single-gene malignant tumor caused by mutations in the SMARCA4 gene. SDUS has a poor prognosis, with no established treatment strategy at present. Further, there is a lack of relevant research on the role of the immune microenvironment in SDUS worldwide. Here, we report a case of SDUS that was diagnosed and analysed using morphological, immunohistochemical, and molecular detection techniques, along with the analysis of the immune microenvironment. By immunohistochemistry, the tumor cells showed retained INI-1 expression, focal CD10 expression, and loss of BRG1, CK-pan, synaptophysin, desmin, and ER expression. Further, some of the immune cells expressing CD3 and CD8 had infiltrated into the SDUS, but no PD-L1 expression was detected. The multiple immunofluorescent staining results showed that a proportion of the immune cells and SDUS cells expressed CD8/CD68/PD-1/PD-L1. Therefore, our report will help in the diagnostic awareness of SDUS.

Retinoblastoma gene expression profiling based on bioinformatics analysis.

BACKGROUND: Retinoblastoma (RB) is frequently occurring malignant tumors that originate in the retina, and their exact cause and development mechanisms are yet to be fully comprehended. In this study, we identified possible biomarkers for RB and delved into the molecular mechanics linked with such markers. METHODS: In this study GSE110811 and GSE24673 were analyzed. Weighted gene co-expression network analysis (WGCNA) was applied to screen modules and genes associated with RB. By overlapping RB-related module genes with differentially expressed genes (DEGs) between RB and control samples, differentially expressed retinoblastoma genes (DERBGs) were acquired. A gene ontology (GO) enrichment analysis and a kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis were conducted to explore the functions of these DERBGs. To study the protein interactions of DERBGs, a protein-protein interaction (PPI) network was constructed. Hub DERBGs were screened using the least absolute shrinkage and selection operator (LASSO) regression analysis, as well as the random forest (RF) algorithm. Additionally, the diagnostic performance of RF and LASSO methods was evaluated using receiver operating characteristic (ROC) curves and single-gene gene set enrichment analysis (GSEA) was conducted to explore the potential molecular mechanisms involved with these Hub DERBGs. In addition, the competing endogenous RNA (ceRNA) regulatory network of Hub DERBGs was constructed. RESULT: About 133 DERBGs were found to be associated with RB. GO and KEGG enrichment analyses revealed that the important pathways of these DERBGs. Furthermore, the PPI network revealed 82 DERBGs interacting with each other. By RF and LASSO methods, PDE8B, ESRRB, and SPRY2 were identified as Hub DERBGs in patients with RB. From the expression assessment of Hub DERBGs, it was found that the levels of expression of PDE8B, ESRRB, and SPRY2 were significantly decreased in the tissues of RB tumors. Secondly, single-gene GSEA revealed a connection between these 3 Hub DERBGs and oocyte meiosis, cell cycle, and spliceosome. Finally, the ceRNA regulatory network revealed that hsa-miR-342-3p, hsa-miR-146b-5p, hsa-miR-665, and hsa-miR-188-5p may play a central role in the disease. CONCLUSION: Hub DERBGs may provide new insight into RB diagnosis and treatment based on the understanding of disease pathogenesis.

Low-power consumption InP-based optical phase arrays with non-uniformly spaced output waveguides.

Optical Phase Arrays (OPAs) are expected to be an ideal solution to achieve beam shaping, laser radar (LIDAR), free-space optical communications, and spatially resolved optical sensors, etc. We demonstrated a low-power consumption 32-channel OPA with non-uniformly spaced waveguides based on InP substrate. The phase shifters are based on a p-i-n structure which are operated with reverse bias and have a low power consumption. Besides, in order to improve the performance especially to obtain larger steering angle and narrower beam divergence without increasing the number of channels, we have optimized the spacing between the output waveguides. The fabricated OPA achieved a steering angle of 35° with the side lobe suppression ratio more than 8.2 dB across the angle range from -20° to 20° in the far field, which is the largest phase tuning steering angle reported by InP-based OPAs as far as we know. The divergence angle is about 0.46° in the phase steering dimension and the power consumption of the OPA at each steering angle is lower than 7.5 mW.

Narrow linewidth electro-optically tuned multi-channel interference widely tunable semiconductor laser.

A narrow linewidth electro-optically tuned multi-channel interference (MCI) widely tunable semiconductor laser based on carrier injection is demonstrated in this paper. The MCI laser with a common phase section and a semiconductor optical amplifier (SOA) is packaged into a 16-pin butterfly box. The laser is characterized by a strategy: shifting the longitudinal mode and then aligning the reflection peak, which obtains a quasi-continuous tuning range over 48 nm. The corresponding side mode suppression ratios (SMSRs) are higher than 40 dB and frequency deviations from ITU-grid are less than ± 1 GHz. Threshold currents are less than 28 mA. Fiber coupled output powers are higher than 20 mW and power variations with fixed gain and SOA currents are less than 0.8 dB over the whole tuning range. Lorentzian linewidths are less than 320 kHz over the entire tuning range, which is one of the lowest results for monolithic widely tunable semiconductor lasers tuned by carrier injection. These results demonstrate the potential prospects of the MCI laser with carrier injection in the field of optical sensing and optical communications.

Wide-waveguide high-power low-RIN single-mode distributed feedback laser diodes for optical communication.

We present an 8-µm-wide 800-µm-long high-power, single-mode and low RIN DFB laser using a dual-waveguide structure. The introduced passive lower waveguide has weakenes the lateral optical confinement for the ridge waveguide, and thus reduces losses caused by the p-doped layers and maintains single mode stability of the laser. The fabricated laser exhibited an output power higher than 170 mW and a relative intensity noise (RIN) below -157 dB/Hz along with a side-mode suppression-ratio (SMSR) over 55 dB. The temperature tuning from -10°C to 60°C allows an 8.6 nm wavelength tunability with a variation coefficient of 0.12 nm/K. The relaxation oscillation frequency is around 8 GHz, and the linewidth is about 250 kHz at 100 mW output power for the fabricated laser. The characteristics of the proposed high-power laser, including high slope efficiency, single mode stability and low noise, make it a suitable candidate for optical communication.

Characteristics of Prognostic Programmed Cell Death-Related Long Noncoding RNAs Associated With Immune Infiltration and Therapeutic Responses to Colon Cancer.

Programmed cell death (PCD) plays an important role in the onset and progression of various cancers. The molecular events surrounding the occurrence of abnormally expressed long noncoding RNAs (lncRNAs) leading to colon cancer (CC) have become a focus. We comprehensively evaluated the roles of PCD-related lncRNAs in the clinical management of CC and their immune responses. Therefore, we screened 41 prognostic PCD-related lncRNAs in The Cancer Genome Atlas database using co-expression analysis and assigned patients to groups according to the results of cluster analysis. The immune response and functions of cluster 2 were substantially suppressed, which might explain the poor prognosis in this group. A prognostic model comprising eight PCD-related lncRNAs was developed, and its effectiveness was verified using an external database. High-and low-risk groups had different epigenetic modifications and changes in immune cell infiltration. Patients in the high-risk group were resistant to immunotherapy and various chemotherapeutic drugs. Studies in vitro and in vivo further confirmed a carcinogenic role of the lncRNA U62317.4. Our findings of the prognostic value of PCD-related lncRNAs revealed their important roles in immune response disorders, thus providing valuable insights into the clinical management and molecular mechanisms of CC.

Development and validation of a deep learning system to screen vision-threatening conditions in high myopia using optical coherence tomography images.

BACKGROUND/AIMS: To apply deep learning technology to develop an artificial intelligence (AI) system that can identify vision-threatening conditions in high myopia patients based on optical coherence tomography (OCT) macular images. METHODS: In this cross-sectional, prospective study, a total of 5505 qualified OCT macular images obtained from 1048 high myopia patients admitted to Zhongshan Ophthalmic Centre (ZOC) from 2012 to 2017 were selected for the development of the AI system. The independent test dataset included 412 images obtained from 91 high myopia patients recruited at ZOC from January 2019 to May 2019. We adopted the InceptionResnetV2 architecture to train four independent convolutional neural network (CNN) models to identify the following four vision-threatening conditions in high myopia: retinoschisis, macular hole, retinal detachment and pathological myopic choroidal neovascularisation. Focal Loss was used to address class imbalance, and optimal operating thresholds were determined according to the Youden Index. RESULTS: In the independent test dataset, the areas under the receiver operating characteristic curves were high for all conditions (0.961 to 0.999). Our AI system achieved sensitivities equal to or even better than those of retina specialists as well as high specificities (greater than 90%). Moreover, our AI system provided a transparent and interpretable diagnosis with heatmaps. CONCLUSIONS: We used OCT macular images for the development of CNN models to identify vision-threatening conditions in high myopia patients. Our models achieved reliable sensitivities and high specificities, comparable to those of retina specialists and may be applied for large-scale high myopia screening and patient follow-up.

Stereotactic body radiation therapy with sequential S-1 for patients with locally advanced pancreatic cancer and poor performance status: An open-label, single-arm, phase 2 trial.

PURPOSE: The optimal treatment for a particularly neglected group of patients with locally advanced pancreatic cancer (LAPC) and poor performance status, who are usually excluded from most clinical trials, is required. Therefore, we aim to investigate the efficacy and safety of stereotactic body radiation therapy (SBRT) with sequential S-1 for those patients. METHODS: Eligible patients had histologically and radiographically confirmed LAPC and ECOG performance status of 2 or more points determined by two independent physicians. Radiation doses ranged from 35-40 Gy/5f. S-1 was taken orally, twice daily, at a dose of 80 mg/m2 for 28 days, followed by a 14-day interval, which repeated for 6 cycles and was initiated one month after SBRT. The primary endpoint was 1-year overall survival (OS). The secondary endpoints were OS, progression free survival (PFS), treatment-related toxicity and quality of life. The study was registered at ClinicalTrials.gov: NCT02704143. RESULTS: Sixty-three patients were enrolled. At the time of data cut-off, all patients died. No patients were lost to follow-up. Median follow-up was 15.8 months (95%CI 12.9-18.7 months). One-year OS was noted in 46 of 63 patients (73.0%, 95%CI 67.4%-78.6%). The median OS and PFS was 14.4 (95%CI 13.2-15.6 months) and 10.1 months (95%CI 9.7-10.5 months) respectively. Eighteen patients (28.6%) had grade 3 toxicity. According to Quality of Life Questionnaire-Core 30, significant improvements of abdominal pain were found, and patients with poorer baseline global health status had greater improvement of health status and pain relief after treatment. CONCLUSIONS: SBRT with sequential S-1 shows promising efficacy and acceptable toxicity in poor performance status patients with LAPC.

Identification and Exploration of Novel Macrophage M2-Related Biomarkers and Potential Therapeutic Agents in Endometriosis.

Endometriosis (EM) is a chronic neuroinflammatory disorder that is associated with pain and infertility that affects ∼10% of reproductive-age women. The pathophysiology and etiology of EM remain poorly understood, and diagnostic delays are common. Exploration of the underlying molecular mechanism, as well as novel diagnostic biomarkers and therapeutic targets, is urgently needed. Inflammation is known to play a key role in the development of lesions, which are a defining feature of the disorder. In our research, the CIBERSORT and WGCNA algorithms were used to establish a weighted gene co-expression network and to identify macrophage-related hub genes using data downloaded from the GEO database (GSE11691, 7305). The analysis identified 1,157 differentially expressed genes (DEGs) in EM lesions, of which five were identified as being related to M2 macrophages and were validated as differentially expressed by qRT-PCR and immunohistochemistry (IHC). Of these putative novel biomarker genes, bridging integrator 2 (BIN2), chemokine receptor 5 (CCR5), and macrophage mannose receptor 1 (MRC1) were upregulated, while spleen tyrosine kinase (SYK) and metalloproteinase 12 (ADAM12) were downregulated in ectopic endometria vs. normal endometria. Meanwhile, 23 potentially therapeutic small molecules for EM were obtained from the cMAP database, among which topiramate, isoflupredone, adiphenine, dexverapamil, MS-275, and celastrol were the top six molecules with the highest absolute enrichment values. This is our first attempt to use the CIBERSORT and WGCNA algorithms for the identification of novel Mϕ2 macrophage-related biomarkers of EM. Our findings provide novel insights into the impact of immune cells on the etiology of EM; nevertheless, further investigation of these key genes and therapeutic drugs is needed to validate their effects on EM.

Anthropogenic disturbances caused declines in the wetland area and carbon pool in China during the last four decades.

Wetlands are among the natural ecosystems with the highest soil carbon stocks on Earth. However, how anthropogenic disturbances have impacted the quantity and distribution of wetland carbon pool in China is not well understood. Here we used a comprehensive countrywide wetland inventory and Landsat 8 data to document the spatial patterns in China's wetland areas and carbon pools and to understand the underlying causes of their changes from the 1980s to 2010s. We found that the wetland area and carbon pool have decreased from 4.11 × 105  km2 and 15.2 Pg C in the 1980s to 2.14 × 105  km2 and 7.6 Pg C in the 2010s, respectively. Using the human influence index (HII) as a quantitative measure of anthropogenic disturbance intensity, we found a positive relationship between the HII values and wetland decreases in many regions and across China as a whole-which have increased 17% during the time period-indicating that anthropogenic disturbances have been a major factor causing wetland destruction in recent decades. This study provides new evidence for recent changes in China's wetland carbon pool and emphasizes the importance of mitigating anthropogenic disturbances for wetland conservation.

Narrow-linewidth thermally tuned multi-channel interference laser integrated with a SOA and spot size converter.

A narrow-linewidth thermally tuned multi-channel interference (MCI) laser integrated with a semiconductor optical amplifier (SOA) and spot size converter (SSC) is demonstrated in this paper. A MCI laser integrated with SOA through chirped grating is successfully realized for the first time, which achieves a tuning range of more than 42.5 nm with side-mode suppression ratios (SMSRs) higher than 48 dB and Lorentzian linewidth below 100 kHz. InGaAlAs multiple quantum wells (MQWs) and thermal tuning are used to reduce linewidth. The integration of SSC greatly improves the coupling efficiency between the laser and a lensed fiber. The MCI laser integrated with SSC achieves more than 16 dBm output power coupled into a lensed fiber. Air layers are fabricated in the phase sections to increase the heating efficiency. The total thermal tuning power is below 20 mW across the whole tuning range.

Distinguishing Microvasculature Features of Vogt-Koyanagi-Harada in Patients in Acute and Convalescent Phases Using Optical Coherence Tomography Angiography.

Purpose: To evaluate retinal and choroidal microvascular features of VKH patients in acute and convalescent phases after treatment using OCTA.Methods: A prospective, observational study was conducted in patients with initial VKH at the acute stage (n = 15) and healthy participants (n = 15) served as controls. After 3-month systemic corticosteroid treatment, patients' vascular parameters were recorded by OCTA before and after treatment and compared with results observed in healthy participants.Results: Our findings first uncovered that there are two types of abnormalities in the choriocapillary layer of patients with VKH in the acute stage: one is characterized as multiple dark spots of choriocapillary flow void and the other involves highly reflective areas surrounded by light spots with an increased flow area. During the convalescent stage, all eyes showed multifocal dark spots in the choriocapillary layer, leading to a reduced choroidal flow area.Conclusions: OCTA provides a better display of the microvascular appearance of the choroid to noninvasively evaluate choriocapillaris abnormalities in VKH disease.

Genetic landscape and autoimmunity of monocytes in developing Vogt-Koyanagi-Harada disease.

Vogt-Koyanagi-Harada (VKH) disease is a systemic autoimmune disorder affecting multiple organs, including eyes, skin, and central nervous system. It is known that monocytes significantly contribute to the development of autoimmune disease. However, the subset heterogeneity with unique functions and signatures in human circulating monocytes and the identity of disease-specific monocytic populations remain largely unknown. Here, we employed an advanced single-cell RNA sequencing technology to systematically analyze 11,259 human circulating monocytes and genetically defined their subpopulations. We constructed a precise atlas of human blood monocytes, identified six subpopulations-including S100A12, HLA, CD16, proinflammatory, megakaryocyte-like, and NK-like monocyte subsets-and uncovered two previously unidentified subsets: HLA and megakaryocyte-like monocyte subsets. Relative to healthy individuals, cellular composition, gene expression signatures, and activation states were markedly alternated in VKH patients utilizing cell type-specific programs, especially the CD16 and proinflammatory monocyte subpopulations. Notably, we discovered a disease-relevant subgroup, proinflammatory monocytes, which showed a discriminative gene expression signature indicative of inflammation, antiviral activity, and pathologic activation, and converted into a pathologic activation state implicating the active inflammation during VKH disease. Additionally, we found the cell type-specific transcriptional signature of proinflammatory monocytes, ISG15, whose production might reflect the treatment response. Taken together, in this study, we present discoveries on accurate classification, molecular markers, and signaling pathways for VKH disease-associated monocytes. Therapeutically targeting this proinflammatory monocyte subpopulation would provide an attractive approach for treating VKH, as well as other autoimmune diseases.

Quantitative Analysis of Anterior Chamber Inflammation Using the Novel CASIA2 Optical Coherence Tomography.

PURPOSE: We evaluated the clinical utility of a novel anterior segment optical coherence tomography (AS-OCT) device, CASIA2, to evaluate parameters indicative of anterior chamber (AC) inflammation severity in uveitis, including AC cell number, flare, and keratic precipitates (KPs). DESIGN: Prospective evaluation of a diagnostic device. METHODS: Uveitis eyes were classified into active and inactive groups. The number of hyperreflective dots representing AC cells and optical density ratio (aqueous-to-air relative intensity [ARI] index) for flare qualification were calculated from AS-OCT images. In addition, a program was designed to quantify the posterior corneal surface smoothness (PCSS) of each image for KPs evaluation. The maximum, minimum, and average PCSS values were calculated from 128 images per eye and compared among active uveitis, inactive uveitis, and control eyes. Correlations between Standardization of Uveitis Nomenclature grade and both hyperreflective dot number and ARI index were evaluated. Receiver operating characteristic (ROC) curves were constructed to test the values of these indicators for uveitis diagnosis. RESULTS: AC hyperreflective dot count, ARI index, and maximum and average PCSS values were all significantly higher in the active uveitis group than in the inactive and control groups. Hyperreflective dot count and ARI index were associated with Standardization of Uveitis Nomenclature cell and flare grade. According to ROC curve analysis, maximum PCSS was the best indicator for the diagnosis of uveitis involving the anterior segment, meanwhile the hyperreflective dot number was the best to identify active AC inflammation from the inactive. CONCLUSIONS: Quantification of AC cell number, flare, and KPs using the CASIA2 device is a promising strategy for the objective assessment of AC inflammation.

State Estimation of Hemodynamic Model for fMRI Under Confounds: SSM Method.

Through hemodynamic models, the change of neuronal state can be estimated from functional magnetic resonance imaging (fMRI) signals. Usually, there are confounds in the fMRI signal, which will degrade the performance of the estimation for the neuronal state change. For the reason, this paper introduces a state-space model with confounds, from a conventional hemodynamic model. In this model, a successive state estimation method requires a state value vector, an error covariance, an innovation covariance, and a cross covariance to be re-derived. Thus, a confounds square-root cubature Kalman smoothing (CSCKS) algorithm is proposed in this paper. We use a Balloon-Windkessel model to generate simulation data and add confounds signals to evaluate the performance of the proposed algorithm. The experiment results show that when the signal-to-interference ratio is less than 21 dB, the CSCKS proposed in this paper reduced estimation error to 16%, whereas the traditional algorithm reduced it to only 73%.

Microvascular changes after conbercept therapy in central retinal vein occlusion analyzed by optical coherence tomography angiography.

AIM: To investigate microvascular changes in eyes with central retinal vein occlusion (CRVO) complicated by macular edema before and after intravitreal conbercept injection and evaluate correlations between these changes and best-corrected visual acuity (BCVA) and retinal thickness. METHODS: Twenty-eight eyes of 28 patients with macular edema caused by CRVO were included in this retrospective study. All patients received a single intravitreal conbercept injection to treat macular edema. BCVA and the results of optical coherence tomography angiography (OCTA) automatic measurements of the vessel density in the superficial (SCP) and deep retinal capillary plexus (DCP), the foveal avascular zone (FAZ) area, the FAZ perimeter (PERIM), the vessel density within a 300-µm wide ring surrounding the FAZ (FD-300), the acircularity index (AI), the choriocapillaris flow area, and retinal thickness were recorded before and at one month after treatment and compared with the results observed in age- and sex-matched healthy subjects. RESULTS: The vessel density in the SCP and DCP, the FD-300, and the flow area of the choriocapillaris were all significantly lower in CRVO eyes than in healthy eyes, while the AI and retinal thickness were significantly higher (all P<0.05). After treatment, retinal thickness was significantly decreased, and the mean BCVA had markedly improved from 20/167 to 20/65 (P=0.0092). The flow area of the choriocapillaris was also significantly improved, which may result from the reduction of shadowing effect caused by the attenuation of macular edema. However, there were no significant changes in SCP and DCP vessel density after treatment. The flow area of the choriocapillaris at baseline was negatively correlated with retinal thickness. CONCLUSION: OCTA enables the non-invasive, layer-specific and quantitative assessment of microvascular changes both before and after treatment, and can therefore be used as a valuable imaging tool for the evaluation of the follow-up in CRVO patients.

Study of the spatial and temporal distribution of accumulated solids in an experimental vertical-flow constructed wetland system.

Clogging is the most serious problem in the operation of subsurface flow constructed wetlands (SSF CWs) and is caused by the accumulation of solids in substrates. Study of the solids accumulation process can provide a more accurate reference for the management and maintenance of SSF CWs. In this study, an experimental vertical-flow constructed wetland system was recreated in the lab, and substrates with different depth were sampled through different operation time to reveal the spatial and temporal distribution of accumulated solids. During the study, particulates mainly accumulated through adsorption along the gravel surface. Therefore, the matrix could still provide sufficient space for the particles to pass through and be intercepted or adsorbed into the system at a constant rate. At the end of the study, an increasing number of large particles had been intercepted and were accumulated in the 0-2cm layer of the matrix, indicating a significant decrease in the pore diameter at the top substrate layer. The spatial and temporal accumulation of substrate particulates during the study period was accurately simulated by first-order kinetics models, and the simulated results were in good agreement with measured values.

Heterodyne locking of a fully integrated optical phase-locked loop with on-chip modulators.

We design and experimentally demonstrate a highly integrated heterodyne optical phase-locked loop (OPLL) consisting of an InP-based coherent photonic receiver, high-speed feedback electronics, and an RF synthesizer. Such coherent photonic integrated circuits contain two widely tunable lasers, semiconductor optical amplifiers, phase modulators, and a pair of balanced photodetectors. Offset phase-locking of the two lasers is achieved by applying an RF signal to an on-chip optical phase modulator following one of the lasers and locking the other one to a resulting optical sideband. Offset locking frequency range >16 GHz is achieved for such a highly sensitive OPLL system which can employ up to the third-order-harmonic optical sidebands for locking. Furthermore, the rms phase error between the two lasers is measured to be 8°.