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1.
Opt Lett ; 49(15): 4198-4201, 2024 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-39090893

RESUMEN

The complex external environment, such as obstruction and turbulence, poses significant limitations on the applications of rotational Doppler detection. The active manipulation of randomly fluctuated light has been proven effective in mitigating external environmental perturbations. Here, as an example, a partially coherent source with petal-like focal (or far) field distribution is constructed specifically for detecting rotational Doppler frequency shifts. The experiment involved conducting rotational Doppler detection under obstruction or turbulence conditions, and the results are compared with the fully coherent counterpart. The results demonstrate that the use of a partially coherent source can address the frequency-shift broadening problem due to the obstruction-induced beam information loss and mitigate it due to the turbulence-induced beam misalignment. These advantages make the proposed approach applicable to velocity metrology in complex environments.

2.
J Nanobiotechnology ; 22(1): 445, 2024 Jul 28.
Artículo en Inglés | MEDLINE | ID: mdl-39069607

RESUMEN

BACKGROUND: The incidence of osteochondral defects caused by trauma, arthritis or tumours is increasing annually, but progress has not been made in terms of treatment methods. Due to the heterogeneous structure and biological characteristics of cartilage and subchondral bone, the integration of osteochondral repair is still a challenge. RESULTS: In the present study, a novel bilayer hydrogel scaffold was designed based on anatomical characteristics to imitate superficial cartilage and subchondral bone. The scaffold showed favourable biocompatibility, and the addition of an antioxidant nanozyme (LiMn2O4) promoted reactive oxygen species (ROS) scavenging by upregulating antioxidant proteins. The cartilage layer effectively protects against chondrocyte degradation in the inflammatory microenvironment. Subchondral bionic hydrogel scaffolds promote osteogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs) by regulating the AMPK pathway in vitro. Finally, an in vivo rat preclinical osteochondral defect model confirmed that the bilayer hydrogel scaffold efficiently promoted cartilage and subchondral bone regeneration. CONCLUSIONS: In general, our biomimetic hydrogel scaffold with the ability to regulate the inflammatory microenvironment can effectively repair osteochondral defects. This strategy provides a promising method for regenerating tissues with heterogeneous structures and biological characteristics.


Asunto(s)
Regeneración Ósea , Hidrogeles , Células Madre Mesenquimatosas , Osteogénesis , Ratas Sprague-Dawley , Andamios del Tejido , Animales , Hidrogeles/química , Hidrogeles/farmacología , Andamios del Tejido/química , Ratas , Células Madre Mesenquimatosas/efectos de los fármacos , Regeneración Ósea/efectos de los fármacos , Osteogénesis/efectos de los fármacos , Condrocitos/efectos de los fármacos , Masculino , Diferenciación Celular/efectos de los fármacos , Inflamación , Ingeniería de Tejidos/métodos , Especies Reactivas de Oxígeno/metabolismo , Condrogénesis/efectos de los fármacos , Cartílago/efectos de los fármacos , Cartílago Articular/efectos de los fármacos , Células Cultivadas
3.
Opt Express ; 31(6): 9308-9318, 2023 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-37157503

RESUMEN

For a partially coherent Bessel-Gaussian (PCBG) vortex beam, information regarding the topological charge (TC) is hidden in the phase of the cross-spectral density (CSD) function. We theoretically and experimentally confirmed that during free-space propagation, the number of coherence singularities is equal to the magnitude of the TC. In contrast to the Laguerre-Gaussian vortex beam, this quantitative relationship only holds for the case with an off-axis reference point for the PCBG vortex beam. The phase winding direction is determined by the sign of the TC. We developed a scheme for CSD phase measurement of PCBG vortex beams and verified the aforementioned quantitative relationship at different propagation distances and coherence widths. The findings of this study may be useful for optical communications.

4.
BMC Endocr Disord ; 23(1): 27, 2023 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-36721144

RESUMEN

BACKGROUNDS: We aimed to explore the relationship between diabetes status and bone mineral density (BMD) among adults with pre-diabetes and diabetes. METHODS: We collected and analyzed five cycles (2005-2006, 2007-2008, 2009-2010, 2013-2014, and 2017-2018) data from NHANES. We removed the individuals containing missing values. The linear regression models were used to explore the relationship between diabetes status and bone mineral density. Finally, we performed subgroup analyzes by age, sex and race to find special populations. RESULT: Finally, 9661 participants with complete data were involved in the study. 944 were diagnosed with pre-diabetes, and 2043 were with diabetes. We found that bone mineral density in the hip, femoral neck, and lumbar spine showed an upward trend in both prediabetic and diabetic patients in the three linear regression models. Further, after subgroup analysis, we found that this trend was more prominent in whites race, women, and those over 50 years old. CONCLUSION: Using NHANES data from 2005 to 2018, we found that patients with abnormal glucose metabolism had increased bone mineral density.


Asunto(s)
Estado Prediabético , Humanos , Adulto , Femenino , Persona de Mediana Edad , Estado Prediabético/epidemiología , Densidad Ósea , Encuestas Nutricionales , Cuello Femoral/diagnóstico por imagen , Glucosa
5.
Opt Express ; 30(17): 29923-29939, 2022 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-36242106

RESUMEN

We report on a partially coherent radially polarized power-exponent-phase vortex (PC-RP-PEPV) beam with various distributions of intensity, controllable coherence width, vortex phase, and polarization. The statistical properties of the PC-RP-PEPV beam depend on topological charge, power order, polarization states, and coherence width, which differ from those of conventional radially polarized beams. Here, the initial radial polarization state will transform to complex ellipse polarization state during propagation. By modulating the topological charge of the PC-RP-PEPV beam, the intensity structure of the beam can be adjusted from circular to polygonal. Finally, PC-RP-PEPV beams were experimentally generated, and were consistent with numerical simulation results. This work has applications in optical manipulation, optical measurements, and optical information processing.

6.
BMC Musculoskelet Disord ; 22(1): 614, 2021 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-34246250

RESUMEN

BACKGROUND: C5 nerve root paralysis is a nonnegligible complication after posterior cervical spine surgery (PCSS). The cause of its occurrence remains controversial. The purpose of this study was to analyse the incidence of and risk factors for C5 nerve root paralysis after posterior cervical decompression. METHODS: We retrospectively analysed the clinical data of 640 patients who underwent PCSS in the Department of Orthopaedics, Affiliated Hospital of Qingdao University from September 2013 to September 2019. According to the status of C5 nerve root paralysis after surgery, all patients were divided into paralysis and normal groups. Univariate and multivariate analyses were used to determine the independent risk factors for C5 nerve root paralysis. A receiver operating characteristic (ROC) curve was used to demonstrate the discrimination of all independent risk factors. RESULTS: Multivariate logistic regression analysis revealed that male sex, preoperative cervical spine curvature, posterior longitudinal ligament ossification, and preoperative C4/5 spinal cord hyperintensity were independent risk factors for paralysis, whereas the width of the intervertebral foramina was an independent protective factor for paralysis. The area under the curve (AUC) values of the T2 signal change at C4-C5, sex, cervical foramina width, curvature and posterior longitudinal ligament ossification were 0.706, 0.633, 0.617, 0.637, and 0.569, respectively. CONCLUSIONS: Male patients with C4-C5 intervertebral foramina stenosis, preoperative C4-C5 spinal cord T2 high signal, combined with OPLL, and higher preoperative cervical spine curvature are more likely to develop C5 nerve root paralysis after surgery. Among the above five risk factors, T2 hyperintensity change in C4-C5 exhibits the highest correlation with C5 paralysis and strong diagnostic power. It seems necessary to inform patients who have had cervical spine T2 hyperintensity before surgery of C5 nerve root paralysis after surgery, especially those with altered spinal cord T2 signals in the C4-C5 segment.


Asunto(s)
Vértebras Cervicales , Parálisis , Vértebras Cervicales/diagnóstico por imagen , Vértebras Cervicales/cirugía , Descompresión Quirúrgica/efectos adversos , Femenino , Humanos , Masculino , Parálisis/diagnóstico , Parálisis/epidemiología , Parálisis/etiología , Estudios Retrospectivos , Factores de Riesgo , Raíces Nerviosas Espinales/diagnóstico por imagen , Raíces Nerviosas Espinales/cirugía
7.
J Transl Med ; 18(1): 337, 2020 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-32873319

RESUMEN

BACKGROUND: Immune-related genes (IRGs) have been confirmed to have an important role in tumorigenesis and tumor microenvironment formation. Nevertheless, a systematic analysis of IRGs and their clinical significance in soft tissue sarcoma (STS) patients is lacking. METHODS: Gene expression files from The Cancer Genome Atlas (TCGA) database and Genotype-Tissue Expression (GTEx) were used to select differentially expressed genes (DEGs). Differentially expressed immune-related genes (DEIRGs) were determined by matching the DEG and ImmPort gene sets, which were evaluated by functional enrichment analysis. Unsupervised clustering of the identified DEIRGs was conducted, and associations with prognosis, the tumor microenvironment (TME), immune checkpoints, and immune cells were analyzed simultaneously. Two prognostic signatures, one for overall survival (OS) and one for progression free survival (PFS), were established and validated in an independent set. Finally, two transcription factor (TF)-IRG regulatory networks were constructed, and a crucial regulatory axis was validated. RESULTS: In total, 364 DEIRGs and four clusters were identified. OS, TME scores, five immune checkpoints, and 12 types of immune cells were found to be significantly different among the four clusters. The two prognostic signatures incorporating 20 DEIRGs showed favorable discrimination and were successfully validated. Two nomograms combining signature and clinical variables were generated. The C-indexes were 0.879 (95%CI 0.832 ~ 0.926) and 0.825 (95%CI 0.776 ~ 0.874) for the OS and PFS signatures, respectively. Finally, TF-IRG regulatory networks were established, and the MYH11-ADM regulatory axis was verified in three independent datasets. CONCLUSION: This comprehensive analysis of the IRG landscape in soft tissue sarcoma revealed novel IRGs related to carcinogenesis and the immune microenvironment. These findings have implications for prognosis and therapeutic responses, which reveal novel potential prognostic biomarkers, promote precision medicine, and provide potential novel targets for immunotherapy.


Asunto(s)
Perfilación de la Expresión Génica , Sarcoma , Biomarcadores de Tumor , Regulación Neoplásica de la Expresión Génica , Humanos , Pronóstico , Sarcoma/genética , Microambiente Tumoral/genética
8.
Opt Express ; 28(8): 11493-11513, 2020 Apr 13.
Artículo en Inglés | MEDLINE | ID: mdl-32403660

RESUMEN

A new kind of partially coherent vector beam, named a partially coherent radially polarized fractional vortex (PCRPFV) beam, is introduced as a natural extension of the recently introduced scalar partially coherent fractional vortex beams [Zeng et al., Opt. Express26, 26830 (2018)10.1364/OE.26.026830]. Realizability conditions and propagation formulas for a PCRPFV beam are derived. Statistical properties of a focused PCRPFV beam, such as average intensity, degree of polarization, state of polarization and cross-spectral density matrix, are illustrated in detail and compared with that of a partially coherent radially polarized integer vortex beam and a scalar partially coherent fractional vortex beam. It is found that the statistical properties of a PCRPFV beam are qualitatively different from these simpler beam classes and are strongly determined by the vortex phase (i.e., fractional topological charge) and initial coherence width. We demonstrate experimental generation of PCRPFV beams and confirm their behavior. Our results will be useful for the rotating and trapping of particles, the detection of phase objects, and polarization lidar systems.

9.
Opt Express ; 28(25): 38106-38114, 2020 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-33379630

RESUMEN

We perform a Young's double-slit experiment with a partially coherent vortex beam (PCVB) and explore its cross-spectral density (CSD) at the focal plane after passing through a double-slit. Our results reveal that the phase of the CSD distribution with respect to an on-axis reference point can simultaneously quantitatively characterize the sign and magnitude of the topological charge (TC) carried by such a beam. In particular, the magnitude of the TC is half of the number of coherence singularities and the sign of the TC is determined by the phase winding of the coherence singularities (i.e., counterclockwise- and clockwise increases correspond to positive and negative, respectively). Based on this property, we present and demonstrate experimentally a simple technique to measure the sign and magnitude of the TC of a PCVB through its CSD distribution after a double-slit. Our method allows for easy measurement of the TC by being conceptually simpler than other methods.

10.
Cancer Cell Int ; 20: 259, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32581649

RESUMEN

BACKGROUND: Osteosarcoma (OS) is a common malignant bone tumor originating in the interstitial tissues and occurring mostly in adolescents and young adults. Energy metabolism is a prerequisite for cancer cell growth, proliferation, invasion, and metastasis. However, the gene signatures associated with energy metabolism and their underlying molecular mechanisms that drive them are unknown. METHODS: Energy metabolism-related genes were obtained from the TARGET database. We applied the "NFM" algorithm to classify putative signature gene into subtypes based on energy metabolism. Key genes related to progression were identified by weighted co-expression network analysis (WGCNA). Based on least absolute shrinkage and selection operator (LASSO) Cox proportional regression hazards model analyses, a gene signature for the predication of OS progression and prognosis was established. Robustness and estimation evaluations and comparison against other models were used to evaluate the prognostic performance of our model. RESULTS: Two subtypes associated with energy metabolism was determined using the "NFM" algorithm, and significant modules related to energy metabolism were identified by WGCNA. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) suggested that the genes in the significant modules were enriched in kinase, immune metabolism processes, and metabolism-related pathways. We constructed a seven-gene signature consisting of SLC18B1, RBMXL1, DOK3, HS3ST2, ATP6V0D1, CCAR1, and C1QTNF1 to be used for OS progression and prognosis. Upregulation of CCAR1, and C1QTNF1 was associated with augmented OS risk, whereas, increases in the expression SCL18B1, RBMXL1, DOK3, HS3ST2, and ATP6VOD1 was correlated with a diminished risk of OS. We confirmed that the seven-gene signature was robust, and was superior to the earlier models evaluated; therefore, it may be used for timely OS diagnosis, treatment, and prognosis. CONCLUSIONS: The seven-gene signature related to OS energy metabolism developed here could be used in the early diagnosis, treatment, and prognosis of OS.

11.
BMC Cancer ; 20(1): 1145, 2020 Nov 25.
Artículo en Inglés | MEDLINE | ID: mdl-33238981

RESUMEN

BACKGROUND: Breast cancer is the most common malignancy in women, and it is also the leading cause of death in female patients; the most common pathological type of BC is infiltrating duct carcinoma (IDC). Some nomograms have been developed to predict bone metastasis (BM) in patients with breast cancer. However, there are no studies on diagnostic and prognostic nomograms for BM in newly diagnosed IDC patients. METHODS: IDC patients with newly diagnosed BM from 2010 to 2016 in the Surveillance, Epidemiology and End Results (SEER) database were reviewed. Multivariate logistic regression analysis was used to identify risk factors for BM in patients with IDC. Univariate and multivariate Cox proportional hazards regression analysis were used to explore the prognostic factors of BM in patients with IDC. We then constructed nomograms to predict the risk and prognosis of BM for patients with IDC. The results were validated using bootstrap resampling and retrospective research on 113 IDC patients with BM from 2015 to 2018 at the Affiliated Hospital of Chengde Medical University. RESULTS: This study included 141,959 patients diagnosed with IDC in the SEER database, of whom 2383 cases were IDC patients with BM. The risk factors for BM in patients with IDC included sex, primary site, grade, T stage, N stage, liver metastasis, race, brain metastasis, breast cancer subtype, lung metastasis, insurance status, and marital status. The independent prognostic factors were brain metastases, race, grade, surgery, chemotherapy, age, liver metastases, breast cancer subtype, insurance status, and marital status. Through calibration, receiver operating characteristic curve and decision curve analyses, we found that the nomogram for predicting the prognosis of IDC patients with BM displayed great performance both internally and externally. CONCLUSION: These nomograms are expected to be a precise and personalized tool for predicting the risk and prognosis for BM in patients with IDC. This will help clinicians develop more rational and effective treatment strategies.


Asunto(s)
Neoplasias Óseas/secundario , Neoplasias Encefálicas/secundario , Neoplasias de la Mama/patología , Carcinoma Ductal de Mama/patología , Neoplasias Pulmonares/secundario , Nomogramas , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias Óseas/terapia , Neoplasias Encefálicas/terapia , Neoplasias de la Mama/terapia , Carcinoma Ductal de Mama/terapia , Terapia Combinada , Femenino , Estudios de Seguimiento , Humanos , Neoplasias Pulmonares/terapia , Masculino , Persona de Mediana Edad , Pronóstico , Estudios Retrospectivos , Factores de Riesgo , Programa de VERF , Adulto Joven
12.
BMC Cancer ; 20(1): 494, 2020 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-32487048

RESUMEN

BACKGROUND: Bone metastasis (BM) is one of the common sites of hepatocellular carcinoma (HCC), and the prognosis of BM patients is worse than patients without it. Our study aimed to identify predictors and prognostic factors of BM in HCC patients and develop two nomograms to quantify the risk of BM and the prognosis of HCC patients with BM. METHODS: We retrospectively reviewed the data of patients who were diagnosed as HCC between 2010 and 2015 in the Surveillance, Epidemiology, and End Results (SEER) database. Independent predictors for BM from HCC patients were determined by the univariate and multivariate logistic regression analysis. Independent prognostic factors for HCC patients with BM were identified by univariate and multivariate Cox regression analysis. Two nomograms were established and evaluated by calibration curves, receiver operating characteristic (ROC) curve, and decision curve analysis (DCA). RESULTS: Nine thousand and forty-seven patients were included. The independent risk factors of BM in newly diagnosed HCC patients are sex, grade, T stage, and N stage. The independent prognostic factors for HCC patients with BM are radiotherapy, chemotherapy, and lung metastasis. The AUC of diagnostic nomogram were 0.726 in the training set and 0.629 in the testing set. For the prognostic nomogram, the AUCs of 6-, 9-, and 12-months were 0.753, 0.799, and 0.732 in the training set and 0.698, 0.770, and 0.823 in the validation set. The calibration curve and DCA indicated the good performance of the nomogram. CONCLUSIONS: Two nomograms were established to predict the incidence of BM in HCC patients and the prognosis of HCC patients with BM, respectively. Both nomograms have satisfactory accuracy, and clinical utility may benefit for clinical decision-making.


Asunto(s)
Neoplasias Óseas/diagnóstico , Carcinoma Hepatocelular/diagnóstico , Neoplasias Hepáticas/patología , Nomogramas , Factores de Edad , Anciano , Neoplasias Óseas/epidemiología , Neoplasias Óseas/secundario , Carcinoma Hepatocelular/epidemiología , Carcinoma Hepatocelular/secundario , Toma de Decisiones Clínicas/métodos , Estudios de Factibilidad , Femenino , Humanos , Incidencia , Estimación de Kaplan-Meier , Neoplasias Hepáticas/mortalidad , Neoplasias Hepáticas/terapia , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Curva ROC , Estudios Retrospectivos , Medición de Riesgo/métodos , Factores de Riesgo , Programa de VERF/estadística & datos numéricos , Factores Sexuales
13.
BMC Pulm Med ; 20(1): 180, 2020 Jun 24.
Artículo en Inglés | MEDLINE | ID: mdl-32580706

RESUMEN

BACKGROUND: This retrospective study aimed to investigate the prognostic value of the neutrophil-to-lymphocyte ratio (NLR) and albumin for 30-day mortality in patients with postoperative acute pulmonary embolism (PAPE). METHODS: We retrospectively reviewed the medical records of 101 patients with PAPE admitted from September 1, 2012, to March 31, 2019. The characteristics, surgical information, admission examination data and mortality within 30 days after PAPE were obtained from our electronic medical recording system and follow-up. The associations between the NLR, PLR, and other predictors and 30-day mortality were analyzed with univariate and multivariate analyses. Then, the nomogram including the independent predictors was established and evaluated. RESULTS: Twenty-four patients died within 30 days, corresponding to a 30-day mortality rate of 23.8%. The results of the multivariate analysis indicated that both the NLR and albumin were independent predictors for 30-day mortality in patients with PAPE. The probability of death increased by approximately 17.1% (OR = 1.171, 95% CI: 1.073-1.277, P = 0.000) with a one-unit increase in the NLR, and the probability of death decreased by approximately 15.4% (OR = 0.846, 95% CI: 0.762c-0.939, P = 0.002) with a one-unit increase in albumin. The area under the curve of the nomogram was 0.888 (95% CI: 0.812-0.964). CONCLUSION: Our findings showed that an elevated NLR and decreased albumin were related to poor prognosis in patients with PAPE. The NLR and albumin were independent prognostic factors for PAPE.


Asunto(s)
Linfocitos/citología , Neutrófilos/citología , Embolia Pulmonar/diagnóstico , Embolia Pulmonar/mortalidad , Albúmina Sérica Humana/análisis , Enfermedad Aguda , Anciano , Área Bajo la Curva , Femenino , Humanos , Modelos Logísticos , Recuento de Linfocitos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Nomogramas , Valor Predictivo de las Pruebas , Pronóstico , Embolia Pulmonar/sangre , Curva ROC , Estudios Retrospectivos , Factores de Riesgo , Tasa de Supervivencia , Factores de Tiempo
14.
BMC Musculoskelet Disord ; 21(1): 290, 2020 May 11.
Artículo en Inglés | MEDLINE | ID: mdl-32393314

RESUMEN

BACKGROUND: Percutaneous endoscopic cervical decompression (PECD) is an ideal minimally invasive decompression technique for the treatment of cervical spondylotic radiculopathy (CSR). However, the mainstream is the resection of dorsal bone and removal of free nucleus pulposus. The necessity of excision of ventral osteophytes and hyperplastic ligaments in the treatment of CSR caused by cervical foraminal and/or lateral spinal stenosis (CFa/oLSS) to be discussed. METHODS: We performed a retrospective study of 46 patients with CSR caused by CFa/oLSS from January 2017 to November 2018. These patients received posterior percutaneous endoscopic cervical decompression-ventral bony decompression (PPECD-VBD)(23 cases, classified as VBD group) or posterior percutaneous endoscopic cervical decompression-simple dorsal decompression (PPECD-SDD)(23 cases, classified as SDD group). Following surgery, we recorded Visual Analogue Scale (VAS), Neck Disable Index (NDI), Japanese Orthopaedic Association (JOA) Scores and myodynamia. We further evaluated the changes of cervical curvature and cervical spine motion in the VBD group and recorded the operation time and complications during the follow-up of each patient. RESULTS: All patients underwent successful operations, with an average follow-up time of 16.53 ± 9.90 months. The excellent and good rates in the VBD and SDD groups were 91.29 and 60.87%, respectively. In the SDD group, neck-VAS, arm-VAS, and NDI scores were significantly higher than those of the VBD group at 1 day, 6 months, and 12 months after surgery (P < 0.05), while the JOA scores and improvement rate of JOA were significantly lower than those of the VBD group (P < 0.05). There were no significant differences in terms of angular displacement (AD), horizontal displacement (HD), segmental angle (SA) and cervical curvature (CA) before and after the operation in the VBD group (P > 0.05). CONCLUSION: PPECD-VBD was significantly better than PPECD-SDD as well as PPECD-VBD had no significant effects on cervical spine stability or cervical curvature.


Asunto(s)
Vértebras Cervicales/patología , Discectomía Percutánea/métodos , Endoscopía/métodos , Desplazamiento del Disco Intervertebral/cirugía , Radiculopatía/etiología , Radiculopatía/cirugía , Estenosis Espinal/complicaciones , Adulto , Anciano , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Dolor de Cuello , Dimensión del Dolor , Estudios Retrospectivos , Resultado del Tratamiento , Escala Visual Analógica
15.
Opt Express ; 27(18): 25342-25356, 2019 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-31510407

RESUMEN

Close to the ground, it is generally known that atmospheric turbulence exhibits strong anisotropy, which affects the performance of applications such as free-space optical (FSO) communication. In this paper, we establish a theoretical model for calculating the spiral spectrum, also called the orbital angular momentum (OAM) spectrum, of a Laguerre-Gaussian (LG) beam after propagation through anisotropic turbulence along a horizontal link. This model isolates the effects of anisotropy from other parameters of the turbulence. On the basis of this model, the effects of the anisotropy on the probability density of the OAM spectrum and its corresponding modal crosstalk are studied through numerical examples. Our simulation results show that the width of the OAM spectrum will increase or slightly decrease depending on the specific nature of the anisotropy. In addition, it is demonstrated that the inner scale is more likely to cause modal crosstalk than the outer scale. Some strategies to reduce modal crosstalk in anisotropic turbulence are also discussed. Our results may be useful in OAM-based FSO communication at ground level.

16.
Opt Lett ; 44(9): 2260-2263, 2019 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-31042198

RESUMEN

We report the first, to the best of our knowledge, experimental realization of high-quality dark and antidark diffraction-free beams, first theoretically proposed by Ponomarenko et al. [Opt. Lett.32, 2508 (2007)OPLEDP0146-959210.1364/OL.32.002508]. Our method employs a single spatial light modulator (SLM) and is based on superposing mutually uncorrelated but spatially coherent in the time domain Bessel modes with modal weights proportional to the SLM display times of the corresponding modes. We also experimentally verify diffraction-free properties of the generated beams upon their free space propagation.

17.
Opt Lett ; 44(15): 3881-3884, 2019 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-31368992

RESUMEN

We explore the phase distribution of the cross-spectral density (CSD) function with an off-axis reference point of a focused higher-order partially coherent vortex (PCV) beam in the focal plane. Our results reveal that the numbers of ring dislocations and screw dislocations in the CSD function equal to the magnitudes of the azimuthal mode index and radial mode index of the incident beam, respectively. In addition, the sign of the azimuthal mode index determines the direction of the phase change of the screw dislocation. This phenomenon can be used to measure the magnitude and sign of the mode indices of a higher-order PCV beam simultaneously. Our results will be useful for quantum information processing, optical storage, and communications.

18.
Opt Express ; 26(21): 26830-26844, 2018 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-30469761

RESUMEN

We introduce a new kind of partially coherent vortex (PCV) beam with fractional topological charge named partially coherent fractional vortex (PCFV) beam and derive the propagation formula for such beam passing through a stigmatic ABCD optical system with the help of the convolution method. We calculate numerically the propagation properties of a PCFV beam focused by a thin lens, and we find that the PCFV beam exhibits unique propagation properties. The opening gap of the intensity pattern and the rotation of the beam spot disappear gradually and the cross-spectral density (CSD) distribution becomes more symmetric and more recognizable with the decrease of the spatial coherence width, being qualitatively different from those of the PCV beam with integral topological charge. Furthermore, we carry out experimental generation of a PCFV beam with controllable spatial coherence, and measure its focusing properties. Our experimental results are consistent with the theoretical predictions.

19.
Opt Express ; 26(25): 33035-33043, 2018 Dec 10.
Artículo en Inglés | MEDLINE | ID: mdl-30645461

RESUMEN

The partially coherent elegant Laguerre-Gaussian (ELG) beam is of importance and exhibits extraordinary characteristics in many fields, such as optical communications and optical trapping. Here, we show a method to measure the topological charge of a partially coherent ELG beam. We find that the number of ring dislocations in the far-field complex degree of coherence is equal to the topological charge |l| of a partially coherent ELG beam, and which is confirmed experimentally. Our results will be useful for applications using partially coherent ELG beams.

20.
Opt Express ; 26(4): 4479-4490, 2018 Feb 19.
Artículo en Inglés | MEDLINE | ID: mdl-29475298

RESUMEN

The complete characterization of spatial coherence is extremely difficult because the mutual coherence function (MCF) is a complex-valued function of four independent Cartesian coordinates. This difficulty limits the ability to control and to optimize the spatial coherence in a broad range of key applications. Here we propose an efficient and robust scheme for measuring the complete MCF of an arbitrary partially coherent beam using self-referencing holography, which does not require any prior knowledge or making any assumptions about the MCF. We further apply our method to lensless diffractive imaging, and experimentally demonstrate the reconstruction of a phase object under spatially partially coherent illumination. This application is particularly useful for imaging at short wavelengths, where the illumination sources lack spatial coherence and no high-quality imaging optics are available.

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