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1.
Nature ; 588(7836): 169-173, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33087935

RESUMO

Cancer therapies that target epigenetic repressors can mediate their effects by activating retroelements within the human genome. Retroelement transcripts can form double-stranded RNA (dsRNA) that activates the MDA5 pattern recognition receptor1-6. This state of viral mimicry leads to loss of cancer cell fitness and stimulates innate and adaptive immune responses7,8. However, the clinical efficacy of epigenetic therapies has been limited. To find targets that would synergize with the viral mimicry response, we sought to identify the immunogenic retroelements that are activated by epigenetic therapies. Here we show that intronic and intergenic SINE elements, specifically inverted-repeat Alus, are the major source of drug-induced immunogenic dsRNA. These inverted-repeat Alus are frequently located downstream of 'orphan' CpG islands9. In mammals, the ADAR1 enzyme targets and destabilizes inverted-repeat Alu dsRNA10, which prevents activation of the MDA5 receptor11. We found that ADAR1 establishes a negative-feedback loop, restricting the viral mimicry response to epigenetic therapy. Depletion of ADAR1 in patient-derived cancer cells potentiates the efficacy of epigenetic therapy, restraining tumour growth and reducing cancer initiation. Therefore, epigenetic therapies trigger viral mimicry by inducing a subset of inverted-repeats Alus, leading to an ADAR1 dependency. Our findings suggest that combining epigenetic therapies with ADAR1 inhibitors represents a promising strategy for cancer treatment.


Assuntos
Adenosina Desaminase/metabolismo , Elementos Alu/efeitos dos fármacos , Elementos Alu/genética , Decitabina/farmacologia , Decitabina/uso terapêutico , Epigênese Genética/efeitos dos fármacos , Proteínas de Ligação a RNA/metabolismo , Transcrição Gênica/efeitos dos fármacos , Imunidade Adaptativa/efeitos dos fármacos , Adenosina Desaminase/deficiência , Elementos Alu/imunologia , Animais , Linhagem Celular Tumoral , Ilhas de CpG/efeitos dos fármacos , Ilhas de CpG/genética , DNA Intergênico/efeitos dos fármacos , DNA Intergênico/genética , DNA Intergênico/imunologia , DNA-Citosina Metilases/antagonistas & inibidores , Retroalimentação Fisiológica , Humanos , Imunidade Inata/efeitos dos fármacos , Helicase IFIH1 Induzida por Interferon/metabolismo , Íntrons/efeitos dos fármacos , Íntrons/genética , Íntrons/imunologia , Sequências Repetidas Invertidas/efeitos dos fármacos , Sequências Repetidas Invertidas/genética , Sequências Repetidas Invertidas/imunologia , Masculino , Camundongos , Mimetismo Molecular/efeitos dos fármacos , Mimetismo Molecular/imunologia , Neoplasias/tratamento farmacológico , Neoplasias/genética , Neoplasias/imunologia , Neoplasias/patologia , RNA de Cadeia Dupla/efeitos dos fármacos , RNA de Cadeia Dupla/genética , RNA de Cadeia Dupla/imunologia , Proteínas de Ligação a RNA/antagonistas & inibidores , Vírus/efeitos dos fármacos , Vírus/imunologia
3.
Eur J Nutr ; 60(6): 3131-3141, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33532874

RESUMO

BACKGROUND: Diabetes is a chronic disease and the prevalence of it is rapidly increasing. Recently, the use of natural products in chronic diseases such as diabetes has gained more attention. Chlorella, a single-celled green alga, is one of them. There have been some studies on the effects of chlorella supplementation in chronic diseases such as NAFLD, prediabetes, and diabetic mice, but none of them examined the effects of chlorella in patients with T2DM. The present study was designed to evaluate the effects of chlorella supplementation on glycemic control, lipid profile, and anthropometric indices in type 2 diabetic patients. METHODS: This study is a double-blind, randomized controlled trial. 84 patients with T2DM assigned into two groups, receiving 1500 mg/day C. vulgaris or placebo for 8 weeks. Anthropometric information, blood pressure, 24-h food intake recall, and blood samples were collected at the beginning and end of the study to determine the changes of FBS, HbA1c, insulin concentration, insulin resistance, and lipid profile. RESULTS: None of the variables investigated in this study showed a significant change after 8 weeks of intervention with C. vulgaris. CONCLUSION: According to the findings of this study, supplementation with C. vulgaris with a dosage of 1500 mg/day for 8 weeks, does not improve the anthropometric measurements, glycemic status, and lipid profile as well. Thus, it cannot be considered as a complementary therapeutic approach to common medications at this dosage and duration. However, future studies with a higher dosage of C. vulgaris and more prolonged than 8 weeks are needed to be done.


Assuntos
Chlorella , Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 2 , Humanos , Glicemia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Suplementos Nutricionais , Método Duplo-Cego , Controle Glicêmico , Lipídeos
4.
J Craniofac Surg ; 32(7): e604-e607, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34183629

RESUMO

BACKGROUND: Individual distinguishing evidence may be an imperative field of measurable investigation which demonstrates higher correct expectation rates. This process of recognizable Evidence is facilitated by the assurance of sex and age. In circumstances where there are fragmented and mangled skeletal remains, sex assurance is moderately troublesome, and it becomes important to set up the precision of cadaver bones. Therefore, this study aims to evaluate sexual dimorphism and age determination by measuring foramen magnum (FM) dimensions in the Iranian population using digital computed tomography scan. METHODS: The study sample consisted of a modern adult Iranian population of 120 males and 109 females (age range: 15-50 years). Length, width, and area of FM, also FM index were measured on base skull computed tomography scan. RESULT: All of the parameters of FM (length, width, area, and FM index), were larger in men than women. The accuracy of sex determination was up to 50.2. The highest accuracy for sex determination was FM width (67.9). This study also helps craniofacial surgeon for exact reference value of FM, which are authorize neurosurgeons' accessibility to the brain stem approach and FM region with minimum retraction. CONCLUSIONS: It can be concluded from the result, that morphometric analyze of FM is useful for sex determination but cannot be suitable for age determination.


Assuntos
Forame Magno , Determinação do Sexo pelo Esqueleto , Adolescente , Adulto , Computadores , Feminino , Forame Magno/diagnóstico por imagem , Humanos , Irã (Geográfico) , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios X , Adulto Jovem
5.
J Cell Biochem ; 119(12): 10195-10203, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30129246

RESUMO

Schwann cells (SCs) are known to be responsible for axonal ensheathing and myelination, and their transplantation is used commonly for treatment of spinal cord injury (SCI). 17ß-estradiol (E2) has also reported for its protective roles in neurons in the transplanted SCs to the SCI model. In the current study, we evaluated the roles of E2 administration before SCs transplantation in targeting SCI-induced axonal degeneration and demyelination. E2 (25 µg/kg, IP) was administered to the male Wistar rats underwent contusive SCI at T10 segment. At 7 days after injury, 1 × 106 SCs were transplanted to the injury epicenter of the spinal cord. The groups were laminectomy, SCI, SCI+E2, and SCI+E2+SCs. Functional recovery was evaluated using the Basso-Bresnahan-Beattie locomotor test. Sections from spinal cord were also assessed for histoloical staining, including Luxol fast blue, Bielschowsky's silver and immunofluorescence evaluation of myelin basic protein (MBP). The SCI group showed impaired locomotion in the hind limb, increased number of cavities within spinal cord, low observable numbers of regenerating fibers, and a significant decrease in the rate of expression for MBP. These changes were counteracted in the treatment groups ( P < 0.05 vs SCI) with no significant changes among them. From the results, it may be concluded that application of E2 and SCs could be effective when axons undergo demyelination and degenerative processes, and their combination could partly provide cumulative outcomes.


Assuntos
Axônios/efeitos dos fármacos , Estradiol/administração & dosagem , Células de Schwann/transplante , Traumatismos da Medula Espinal/terapia , Animais , Axônios/patologia , Terapia Combinada , Doenças Desmielinizantes , Humanos , Locomoção/efeitos dos fármacos , Locomoção/fisiologia , Regeneração Nervosa , Ratos , Recuperação de Função Fisiológica , Traumatismos da Medula Espinal/fisiopatologia
6.
Metab Brain Dis ; 33(4): 1229-1242, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29658057

RESUMO

Spinal cord injury (SCI) is a devastating traumatic event which burdens the affected individuals and the health system. Schwann cell (SC) transplantation is a promising repair strategy after SCI. However, a large number of SCs do not survive following transplantation. Previous studies demonstrated that 17ß-estradiol (E2) protects different cell types and reduces tissue damage in SCI experimental animal model. In the current study, we evaluated the protective potential of E2 on SCs in vitro and investigated whether the combination of hormonal and SC therapeutic strategy has a better effect on the outcome after SCI. Primary SC cultures were incubated with E2 for 72 h. In a subsequent experiment, thoracic contusion SCI was induced in male rats followed by sustained administration of E2 or vehicle. Eight days after SCI, DiI-labeled SCs were transplanted into the injury epicenter in vehicle and E2-treated animals. The combinatory regimen decreased neurological and behavioral deficits and protected neurons and oligodendrocytes in comparison to vehicle rats. Moreover, E2 and SC significantly decreased the number of Iba-1+ (microglia) and GFAP+ cells (astrocyte) in the SCI group. In addition, we found a significant reduction of mitochondrial fission-markers (Fis1) and an increase of fusion-markers (Mfn1 and Mfn2) in the injured spinal cord after E2 and SC treatment. These data demonstrated that E2 protects SCs against hypoxia-induced SCI and improves the survival of transplanted SCs.


Assuntos
Estradiol/uso terapêutico , Fármacos Neuroprotetores/uso terapêutico , Células de Schwann/transplante , Traumatismos da Medula Espinal/terapia , Animais , Terapia Combinada , Estradiol/farmacologia , Masculino , Modelos Animais , Fármacos Neuroprotetores/farmacologia , Ratos , Ratos Wistar , Medula Espinal/efeitos dos fármacos , Medula Espinal/cirurgia , Traumatismos da Medula Espinal/tratamento farmacológico , Traumatismos da Medula Espinal/cirurgia
7.
Lasers Med Sci ; 33(4): 835-841, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29327089

RESUMO

Several techniques have been proposed to obtain a durable bond, and the efficacy of these techniques is assessed by measuring parameters such as bond strength. Laser has provided a bond strength as high as that of acid etching in vitro and has simpler use with shorter clinical time compared to acid etching. This study aimed to compare the efficacy of Er:YAG and Er,Cr:YSGG lasers for etching and bonding of composite to orthodontic brackets. No previous study has evaluated the effect of these particular types of laser. A total of 70 composite blocks were randomly divided into five groups (n = 14): group 1, etching with phosphoric acid for 20 s; group 2, Er:YAG laser irradiation with 2 W power for 10 s; group 3, Er:YAG laser with 3 W power for 10 s; group 4, Er,Cr:YSGG laser with 2 W power for 10 s; group 5, Er,Cr:YSGG laser with 3 W power for 10 s. Metal brackets were then bonded to composites, and after 5000 thermal cycles, they were subjected to shear bond strength test in a universal testing machine after 24 h of water storage. One sample of each group was evaluated under a scanning electron microscope (SEM) to assess changes in composite surface after etching. The adhesive remnant index (ARI) was calculated under a stereomicroscope. Data were statistically analyzed. The mean and standard deviation of shear bond strength were 18.65 ± 3.36, 19.68 ± 5.34, 21.31 ± 4.03, 17.38 ± 6.94, and 16.45 ± 4.26 MPa in groups 1-5, respectively. The ARI scores showed that the bond failure mode in all groups was mainly mixed. The groups were not significantly different in terms of shear bond strength. Er:YAG and Er,Cr:YSGG lasers with the mentioned parameters yield optimal shear bond strength and can be used as an alternative to acid etching for bracket bond to composite.


Assuntos
Colagem Dentária/métodos , Corrosão Dentária/métodos , Humanos , Lasers de Estado Sólido , Braquetes Ortodônticos , Ácidos Fosfóricos/química , Resistência ao Cisalhamento , Propriedades de Superfície
8.
Cell Tissue Res ; 369(2): 303-312, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28413861

RESUMO

Preconditioning of mesenchymal stem cells (MSCs) with melatonin (MT) has shown promising results in animal models of myocardial infarction, renal ischemia and cerebral ischemia. Here, we use this strategy in the liver fibrosis induced by CCl4. There were five groups: normal, CCl4, CCl4 + vehicle, CCl4 + BMMSCs and CCl4 + MT-bone marrow (BM)-derived MSCs (MT-BMMSCs). CCl4 was injected twice weekly for 8 weeks and treatment either with cells or vehicle was performed at the beginning of week 5 with a single dose. BMMSCs were preconditioned with MT for 24 h before injection. MT-BMMSCs had a high ability of homing into the injured liver (P ≤ 0.05 vs. BMMSCs). The CCl4 + MT-BMMSCs group showed higher percentage of glycogen storage but lower percentage of collagen and lipid accumulation (P ≤ 0.05 vs. CCl4 + BMMSCs). The CCl4 + MT-BMMSCs group showed lower expressions of transforming growth factor-ß1 (TGF-ß1) and Bax and lower content of sera alanine aminotransferase (ALT) but higher expressions of matrix metalloproteinases (MMPs) and Bcl2 compared with the BMMSCs group (P ≤ 0.05). The results showed the better therapeutic outcomes of MT preconditioning by probably improving cell homing and also better maintenance of the balance between matrix degrading and accumulating factors.


Assuntos
Células da Medula Óssea/citologia , Cirrose Hepática/terapia , Melatonina/uso terapêutico , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/citologia , Animais , Tetracloreto de Carbono , Hidroxiprolina/metabolismo , Cirrose Hepática/sangue , Cirrose Hepática/patologia , Masculino , Melatonina/farmacologia , Ratos Sprague-Dawley
9.
Opt Express ; 24(21): 23925-23940, 2016 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-27828227

RESUMO

We present a 32 channel indium phosphide integrated pulse shaper with 25 GHz channel spacing, where each channel is equipped with a semiconductor optical amplifier allowing for programmable line-by-line gain control with submicrosecond reconfigurability. We critically test the integrated pulse shaper by using it in comb-based RF-photonic filtering experiments where the precise gain control is leveraged to synthesize high-fidelity RF filters which we reconfigure on a microsecond time scale. Our on-chip pulse shaping demonstration is unmatched in its combination of speed, fidelity, and flexibility, and will likely open new avenues in the field of advanced broadband signal generation and processing.

10.
Opt Express ; 23(3): 2487-510, 2015 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-25836116

RESUMO

Silicon photonics has experienced phenomenal transformations over the last decade. In this paper, we present some of the notable advances in silicon-based passive and active optical interconnect components, and highlight some of our key contributions. Light is also cast on few other parallel technologies that are working in tandem with silicon-based structures, and providing unique functions not achievable with any single system acting alone. With an increasing utilization of CMOS foundries for silicon photonics fabrication, a viable path for realizing extremely low-cost integrated optoelectronics has been paved. These advances are expected to benefit several application domains in the years to come, including communication networks, sensing, and nonlinear systems.

11.
Opt Express ; 22(17): 20678-90, 2014 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-25321272

RESUMO

We design, fabricate and experimentally demonstrate a highly efficient adiabatic mode converter for coupling light into a silicon slot waveguide with a slot width as large as 320 nm. This strip-to-slot mode converter is optimized to provide a measured insertion loss as low as 0.08 dB. Our mode converter provides 0.1 dB lower loss compared to a conventional V-shape mode converter. This mode converter is used to couple light into and out of a 320 nm slot photonic crystal waveguide, and it is experimentally shown to improve the coupling efficiency up to 3.5 dB compared to the V-shape mode converter, over the slow-light wavelength region.

12.
Opt Lett ; 39(4): 941-4, 2014 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-24562247

RESUMO

A 16-element optical phased array integrated on chip is presented for achieving two-dimensional (2D) optical beam steering. The device is fabricated on the silicon-on-insulator platform with a 250 nm silicon device layer. Steering is achieved via a combination of wavelength tuning and thermo-optic phase shifting with a switching power of P(π)=20 mW per channel. Using a silicon waveguide grating with a polycrystalline silicon overlay enables narrow far field beam widths while mitigating the precise etching needed for conventional shallow etch gratings. Using this system, 2D steering across a 20°×15° field of view is achieved with a sidelobe level better than 10 dB and with beam widths of 1.2°×0.5°.

13.
Opt Lett ; 39(10): 3070-3, 2014 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-24978276

RESUMO

We demonstrate subwavelength bidirectional grating (SWG) coupled slot waveguide fabricated in silicon-on-sapphire for transverse electric polarized wave operation at 3.4 µm wavelength. Coupling efficiency of 29% for SWG coupler is experimentally achieved. Propagation loss of 11 dB/cm has been experimentally obtained for slot waveguides. Two-step taper mode converters with an insertion loss of 0.13 dB are used to gradually convert the strip waveguide mode into slot waveguide mode.

14.
Diabetol Metab Syndr ; 16(1): 185, 2024 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-39085907

RESUMO

AIMS: L-carnitine plays a role related to cardiometabolic factors, but its effectiveness and safety in CVD are still unknown. We aim to assess the effect of L-carnitine supplementation on CVD risk factors. METHODS: A systematic literature search was conducted in PubMed, Web of Science, and Scopus until October 2022. The main outcomes were lipid profiles, anthropometric parameters, insulin resistance, serum glucose levels, leptin, blood pressure, and inflammatory markers. The pooled weighted mean difference (WMD) was calculated using a random-effects model. RESULTS: We included the 21 RCTs (n = 2900) with 21 effect sizes in this study. L-carnitine supplementation had a significant effect on TG (WMD = - 13.50 mg/dl, p = 0.039), LDL (WMD = - 12.66 mg/dl, p < 0.001), FBG (WMD = - 6.24 mg/dl, p = 0.001), HbA1c (WMD = -0.37%, p = 0.013) HOMA-IR (WMD = -0.72, p = 0.038 (, CRP (WMD = - 0.07 mg/dl, P = 0.037), TNF-α (WMD = - 1.39 pg/ml, p = 0.033), weight (WMD = - 1.58 kg, p = 0.001 (, BMI (WMD = - 0.28 kg/m2, p = 0.017(, BFP (WMD = - 1.83, p < 0.001) and leptin (WMD = - 2.21 ng/ml, p = 0.003 (in intervention, compared to the placebo group, in the pooled analysis. CONCLUSIONS: This meta-analysis demonstrated that administration of L-carnitine in diabetic and glucose intolerance patients can significantly reduce TG, LDL-C, FBG, HbA1c, HOMA-IR, CRP, TNF-α, weight, BMI, BFP, and leptin levels. PROSPERO registration code: CRD42022366992.

15.
J Health Popul Nutr ; 43(1): 11, 2024 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-38233891

RESUMO

AIM: Vitamin D is a prominent modulator of immunity and respiratory function. It plays a vital role in respiratory diseases such as cystic fibrosis (CF). S. However, there is a dearth of information on patients with CF. The purpose of the meta-analysis is to highlight the importance of following the existing guidelines regarding maintenance of Vitamin D serum levels in patients with CF. METHODS: The systematic search was conducted without utilizing any time or language limitations in original database from the beginning until March 2022. The meta-analysis was performed using a random-effects model. Heterogeneity was determined by I2 statistics and Cochrane Q test. RESULTS: Pooled analysis using the random-effects model of the 8 case-control studies with 13 effect sizes revealed that the serum 25-OH-vitamin D in participants with cystic fibrosis was significantly lower than controls in pediatrics and adolescences (WMD: - 3.41 ng/ml, 95% CI - 5.02, - 1.80, p = < 0.001) and adults (WMD: - 2.60 ng/ml, 95% CI - 4.32, - 0.89, p = 0.003). Based on data from 12 studies (21 effect sizes) with a total of 1622 participants, the prevalence of vitamin D levels of 20-30 ng/ml in CF patients was 36% among pediatrics/adolescents and 63% among adults. In addition, 27% of pediatric/adolescent CF patients and 35% of adult CF patients had vitamin D levels of below 20 ng/ml. CONCLUSIONS: As a result, according to the existing guidelines, our results proved the need to pay attention to the level of vitamin D in these patients.


Assuntos
Fibrose Cística , Deficiência de Vitamina D , Adulto , Adolescente , Humanos , Criança , Fibrose Cística/complicações , Vitamina D , Estudos de Casos e Controles
16.
Cell Rep ; 43(2): 113684, 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38261511

RESUMO

Viral mimicry describes the immune response induced by endogenous stimuli such as double-stranded RNA (dsRNA) from endogenous retroelements. Activation of viral mimicry has the potential to kill cancer cells or augment anti-tumor immune responses. Here, we systematically identify mechanisms of viral mimicry adaptation associated with cancer cell dependencies. Among the top hits is the RNA decay protein XRN1 as an essential gene for the survival of a subset of cancer cell lines. XRN1 dependency is mediated by mitochondrial antiviral signaling protein and protein kinase R activation and is associated with higher levels of cytosolic dsRNA, higher levels of a subset of Alus capable of forming dsRNA, and higher interferon-stimulated gene expression, indicating that cells die due to induction of viral mimicry. Furthermore, dsRNA-inducing drugs such as 5-aza-2'-deoxycytidine and palbociclib can generate a synthetic dependency on XRN1 in cells initially resistant to XRN1 knockout. These results indicate that XRN1 is a promising target for future cancer therapeutics.


Assuntos
Neoplasias , Retroelementos , Humanos , Linhagem Celular , Citosol , Decitabina , Exonucleases , Neoplasias/genética , RNA de Cadeia Dupla , Exorribonucleases , Proteínas Associadas aos Microtúbulos
17.
Opt Express ; 21(1): 60-9, 2013 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-23388896

RESUMO

We demonstrate intra- and inter-board level optical interconnects using polymer waveguides and waveguide couplers consisting of both 45 degree total internal reflection (TIR) mirrors and inkjet-printed micro-lenses. Surface normal couplers consisting of 50 µm × 50 µm waveguides with embedded 45 degree mirrors are fabricated using a nickel mold imprint. Micro-lenses, 70 µm in diameter, are inkjet-printed on top of the mirrors. We characterize the optical transmission between waveguides located on different boards in terms of insertion loss, mirror coupling loss, and free space propagation loss as a function of interconnection distance in free space. Each mirror contributes 1.88 dB loss to the system, corresponding to 65% efficiency. The printed micro-lenses improve the transmission by 2-4 dB (per coupler). Data transmission at 10 Gbps reveals that inter-board interconnects has a bit error rate (BER) of 1.1 × 10(-10) and 6.2 × 10(-13) without and with the micro-lenses, respectively.

18.
Opt Lett ; 38(18): 3608-11, 2013 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-24104826

RESUMO

We investigate the loss mechanism in three-moded multimode-interference couplers that are the building blocks of a compact and low-loss waveguide crossing structure. Broadband silicon waveguide crossing arrays with <0.01 dB insertion loss per crossing are proposed using cascaded multimode-interference couplers, where lateral subwavelength nanostructures are used to reduce the insertions loss. We design and fabricate a 101×101 waveguide crossing array with a pitch of 3.08 µm. Insertion loss of ∼0.02 dB per crossing and crosstalk <-40 dB at 1550 nm operating wavelength and a broad transmission spectrum ranging from 1520 to 1610 nm are experimentally demonstrated.

19.
Opt Lett ; 38(22): 4931-4, 2013 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-24322169

RESUMO

We design and demonstrate a compact and low-power, band-engineered, electro-optic (EO) polymer refilled silicon slot photonic crystal waveguide (PCW) modulator. The EO polymer is engineered for large EO activity and near-infrared transparency. A PCW step coupler is used for optimum coupling to the slow-light mode of the band-engineered PCW. The half-wave switching voltage is measured to be Vπ = 0.97 ± 0.02 V over an optical spectrum range of 8 nm, corresponding to the effective in-device r(33) of 1199 pm/V and V(π) × L = 0.291 ± 0.006 V × mm in a push-pull configuration. Excluding the slow-light effect, we estimate that the EO polymer is poled with an efficiency of 89 pm/V in the slot.

20.
Opt Lett ; 38(18): 3588-91, 2013 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-24104821

RESUMO

We investigate the waveguide dispersion of subwavelength structures, and propose that the waveguide dispersion can be reduced by reducing the period of subwavelength structures. A 3 dB bandwidth increment of 20% has been observed by introducing this concept into previously demonstrated grating couplers. To fully exploit the bandwidth merits of the structures, gratings with interleaved subwavelength structures were designed and fabricated. Two typical types of interleaving geometries have been investigated. Both demonstrated a 1 dB bandwidth ∼70 nm, a 3 dB bandwidth ∼117 nm, and a peak efficiency ∼-5.1 dB at 1570 nm for transverse-electric polarized light. The simulation confirms that the dispersion engineering adds an extra 12 nm to the 1 dB bandwidth.

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