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1.
Cureus ; 16(4): e58187, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38741864

ABSTRACT

This case report presents a unique instance of ascites in acute alcoholic hepatitis (AH) occurring in a non-cirrhotic patient. Comprehensive diagnostic evaluation excluded alternative etiologies, pinpointing sinusoidal non-cirrhotic portal hypertension. Present therapeutic modalities for AH, including steroids and pentoxifylline, offer limited efficacy, necessitating ongoing investigation. Liver transplantation may be contemplated in refractory cases. This case underscores the intricate nature of AH presentations and the challenges in their management, emphasizing the imperative need for continued research to delineate optimal therapeutic strategies. Early intervention remains pivotal in addressing AH complications, underscoring the need for heightened clinical vigilance and proactive treatment approaches in such cases.

2.
Article in English | MEDLINE | ID: mdl-38762711

ABSTRACT

Anticoagulant therapy is a mainstay in the management of patients with cardiovascular disease. The use of conventional anticoagulants carries potential side effects, mainly bleeding. Drugs targeting Factor XI (FXI) have been investigated in randomized controlled trials as a new option with more favorable outcomes. A comprehensive literature search was conducted to identify relevant studies comparing FXI inhibitors to placebo or standard therapy. The primary outcomes were incidence of all bleeding events, major bleeding, and thromboembolism. Secondary outcomes included incidence of all adverse events (AE), serious AE, and all-cause mortality. A total of 11 studies involving 10,536 patients were included. FXI inhibitors were associated with a trend toward reduction of bleeding events and incidence of thromboembolism compared to the control group (placebo/standard therapy). There was no statistically significant difference between both groups in terms of adverse events and all-cause mortality. When compared to enoxaparin, FXI inhibitors significantly reduced the risk of bleeding events (RR = 0.42, 95% CI: 0.23-0.76, P = 0.004) and thromboembolism (RR = 0.59, 95% CI: 0.44-0.77, P = 0.001). On the other hand, when compared to DOACs, FXI inhibitors were associated with a significant reduction in bleeding events but not thromboembolism. Whereas, compared to placebo, FXI inhibitors did not increase the risk of bleeding events, adverse events, or all-cause mortality (P > 0.05). FXI inhibitors could be a safer and more potent option for prevention of thromboembolism than conventional therapy.

4.
J Am Coll Cardiol ; 83(12): 1136-1146, 2024 Mar 26.
Article in English | MEDLINE | ID: mdl-38508846

ABSTRACT

BACKGROUND: Aortic aneurysm is common in patients with coarctation of aorta (COA), but it is unclear whether the risk of aortic aneurysms is due to COA or related to the presence of other risk factors such as bicuspid aortic valve (BAV) and hypertension. OBJECTIVES: The purpose of this study was to assess the relationship among COA, BAV, and thoracic aortic aneurysms. METHODS: A total of 867 patients with COA (COA group) were matched 1:1:1 to 867 patients with isolated BAV (BAV group) and 867 patients without structural heart disease (SHD) (no-SHD group). The COA group was further subdivided into a COA+BAV subgroup (n = 304 [35%]), and COA with tricuspid aortic valve (TAV) (COA+TAV subgroup [n = 563 (65%)]). Aortic dimensions were assessed at baseline and at 3, 5, and 7 years. RESULTS: Compared with the no-SHD group, the COA+BAV subgroup had larger aortic root diameter (37 mm [Q1-Q3: 30-43 mm] vs 32 mm [Q1-Q3: 27-35 mm]; P < 0.001) and mid ascending aorta dimeter (34 mm [Q1-Q3: 29-40 mm] vs 28 mm [Q1-Q3: 24-31 mm]; P = 0.008). Similarly, the BAV group had larger aortic root diameter (37 mm [Q1-Q3: 30-42 mm] vs 32 mm [Q1-Q3: 27-35 mm]; P < 0.001), and mid ascending aorta dimeter (35 mm [Q1-Q3: 30-40 mm] vs 28 mm [Q1-Q3: 24-31 mm]; P < 0.001). Compared with the COA+TAV subgroup, the COA+BAV subgroup and BAV group were associated with larger aortic root and mid ascending aorta diameter at baseline and follow-up. The risk of acute aortic complications was low in all groups. CONCLUSIONS: These findings suggest that BAV (and not COA) was associated with ascending thoracic aorta dimensions, and that patients with COA+TAV were not at a greater risk of developing ascending aortic aneurysms as compared with patients without SHD.


Subject(s)
Aneurysm, Ascending Aorta , Aortic Aneurysm , Aortic Coarctation , Bicuspid Aortic Valve Disease , Heart Valve Diseases , Humans , Aortic Valve/diagnostic imaging , Aortic Coarctation/complications , Aortic Coarctation/diagnostic imaging , Aortic Coarctation/epidemiology , Heart Valve Diseases/complications , Heart Valve Diseases/diagnostic imaging , Heart Valve Diseases/epidemiology , Aortic Aneurysm/etiology
5.
Opt Express ; 32(2): 1218-1230, 2024 Jan 15.
Article in English | MEDLINE | ID: mdl-38297678

ABSTRACT

We report on an Yb:YAG thin-disk multipass amplifier delivering 100 ns long pulses at a central wavelength of 1030 nm with an energy of 330 mJ at a repetition rate of 100 Hz. The beam quality factor at the maximum energy was measured to be M2 < 1.17. The small signal gain is 21.7, and the gain at 330 mJ was measured to be 6.9. The 20-pass amplifier is designed as a concatenation of stable resonator segments in which the beam is alternately Fourier transformed and relay-imaged back to the disk by a 4f-imaging optical scheme stage. The Fourier transform propagation makes the output beam robust against spherical phase front distortions, while the 4f-stage is used to compensate the thermal lens of the thin-disk and to reduce the footprint of the amplifier.

6.
Am J Cardiol ; 211: 98-105, 2024 Jan 15.
Article in English | MEDLINE | ID: mdl-37940012

ABSTRACT

The relative diagnostic and prognostic performance of left ventricular (LV) global longitudinal strain (LVGLS) compared with LV ejection fraction (LVEF) and the role of LVGLS for detecting the early stages of LV systolic dysfunction in adults with repaired coarctation of the aorta are unknown. This study aimed to address these knowledge gaps. We used a retrospective cohort study of adults with repaired coarctation of the aorta who underwent transthoracic echocardiogram (2003 to 2020). LV systolic function was assessed using LVEF (derived from volumetric analysis) and LVGLS (derived from speckle-tracking echocardiography). Of the 795 patients (age 36 ± 14 years), the mean LVEF and LVGLS were 62 ± 11% and 21 ± 4%, respectively. The prevalence of LV systolic dysfunction was higher when assessed using LVGLS than using LVEF (20% vs 6%, p <0.001). Of 795 patients, 94 (12%) patients died, of which 75 (9%) died from cardiovascular causes. LVGLS provided more robust prognostic power in predicting the all-cause mortality than LVEF, as evidenced by a higher C-statistic (0.743, 95% confidence interval 0.730 to 0.755 vs 0.782, 95% confidence interval 0.771 to 0.792, p <0.001). Furthermore, patients with normal LVEF in the setting of reduced LVGLS had a higher risk of all-cause mortality (than patients with normal LVGLS and LVEF) and were at risk for a temporal decrease in LVEF during follow-up. These findings suggest that the use of LVGLS for risk stratification can help identify high-risk patients and provide opportunities for interventions, which would, in turn, improve clinical outcomes. Further studies are required to empirically test these postulates.


Subject(s)
Aortic Coarctation , Ventricular Dysfunction, Left , Adult , Humans , Young Adult , Middle Aged , Prognosis , Aortic Coarctation/diagnostic imaging , Retrospective Studies , Ventricular Function, Left , Stroke Volume
7.
Opt Express ; 31(24): 40687-40704, 2023 Nov 20.
Article in English | MEDLINE | ID: mdl-38041362

ABSTRACT

We present a comprehensive simulative and experimental investigation of how period-chirped pulse compression gratings affect the compressed pulses. A specifically developed ray-tracing tool was used for the simulative investigations. It is shown that the chirp creates a characteristic spatio-spectral error pattern, which leads to a degradation of the beam quality and an increase of the pulse duration. The experimental investigations, for which both a narrow-bandwidth continuous-wave and a pulsed laser beam were guided through a Treacy-compressor comprised of period-chirped gratings, confirm the simulation results and present methods on how to identify the chirp's characteristic error pattern in practice.

8.
CJC Pediatr Congenit Heart Dis ; 2(4): 167-173, 2023 Aug.
Article in English | MEDLINE | ID: mdl-37969860

ABSTRACT

Background: Right ventricular (RV) systolic dysfunction and pulmonary hypertension are associated with mortality in adults with coarctation of aorta (COA). The tricuspid annular plane systolic excursion/RV systolic pressure (TAPSE/RVSP) ratio is a validated noninvasive tool for the assessment of RV-pulmonary arterial (RV-PA) coupling in patients with PA hypertension, but similar data are lacking in adults with COA. The purpose of this study was to assess the relationship between the TAPSE/RVSP ratio and outcomes in this population. Methods: A retrospective cohort study of adults with repaired COA was performed. RV systolic dysfunction was defined as RV free wall strain ≥-24% at baseline, whereas new-onset RV systolic dysfunction was defined RV free wall strain ≥-24% during follow-up. Results: Of 661 patients, TAPSE, RVSP, and TAPSE/pulmonary artery systolic pressure ratio were 22 ± 6 mm, 34 ± 12 mm Hg, and 0.71 (0.48-0.89) mm/mm Hg, respectively. Of 661 patients, 152 (23%) had RV systolic dysfunction at baseline, and TAPSE/RVSP <0.43 mm/mm Hg was the optimal threshold to detect RV systolic dysfunction. TAPSE/RVSP <0.43 mm Hg was associated with RV systolic dysfunction (adjusted odds ratio: 3.11 [1.83-6.19], P = 0.004). Of 509 patients with normal RV systolic function, 42 (8%) and 36 (7%) developed new-onset RV systolic dysfunction and new-onset right heart failure, respectively, during follow-up. TAPSE/RVSP <0.43 mm/mm Hg was associated with new-onset RV systolic dysfunction (adjusted hazard ratio: 1.95 [1.46-2.77], P = 0.008) and new-onset right heart failure (adjusted hazard ratio: 0.81 [0.68-0.92], P = 0.005). Conclusions: The TAPSE/RVSP ratio can potentially be used to identify patients at risk for new-onset RV systolic dysfunction and right heart failure and provide opportunity for proactive interventions to prevent adverse outcomes.


Contexte: La dysfonction systolique du ventricule droit (VD) et l'hypertension pulmonaire sont associées à des décès chez les adultes qui présentent une coarctation de l'aorte (CA). Le rapport entre l'excursion systolique du plan de l'anneau tricuspide (TAPSE pour tricuspid annular plane systolic excursion) et la pression systolique du VD (PSVD) est une méthode non invasive pour évaluer le couplage entre le VD et l'artère pulmonaire (VD-AP), qui a été validée chez les patients atteints d'hypertension de l'AP, mais pour laquelle on ne dispose pas de données similaires chez les adultes qui présentent une CA. La présente étude visait à évaluer la relation entre le rapport TAPSE/PSVD et les résultats de santé chez cette population de patients. Méthodologie: Nous avons mené une étude de cohorte rétrospective auprès d'adultes présentant une CA corrigée. La dysfonction systolique du VD était définie comme une déformation (strain) de la paroi libre du VD (DPLVD) ≥ -24 % au début de l'étude, et une dysfonction systolique inaugurale du VD était définie comme une DPLVD ≥ -24 % détectée lors du suivi. Résultats: Pour l'ensemble des 661 patients de l'étude, les valeurs pour la TAPSE, la PSVD et le rapport TAPSE/pression systolique de l'artère pulmonaire étaient respectivement de 22 ± 6 mm, 34 ± 12 mmHg et 0,71 (0,48-0,89) mm/mmHg. Parmi ces 661 patients, 152 (23 %) présentaient initialement une dysfonction systolique du VD, et un rapport TAPSE/PSVD < 0,43 mm/mmHg constituait le seuil optimal pour la détection d'une dysfonction systolique du VD. Un rapport TAPSE/PSVD < 0,43 mm/mmHg était par ailleurs associé à une dysfonction systolique du VD (rapport de cotes ajusté de 3,11 [1,83-6,19], p = 0,004). Au cours du suivi des 509 patients qui présentaient initialement une fonction systolique normale du VD, 42 patients (8 %) ont présenté une dysfonction systolique inaugurale du VD et 36 patients (7 %) ont présenté une insuffisance cardiaque droite inaugurale. Un rapport TAPSE/PSVD < 0,43 mm/mmHg était associé avec la dysfonction systolique inaugurale du VD (rapport des risques instantanés ajusté de 1,95 [1,46-2,77], p = 0,008), et avec l'insuffisance cardiaque droite inaugurale (rapport des risques instantanés ajusté de 0,81 [0,68-0,92], p = 0,005). Conclusions: Le rapport TAPSE/PSVD pourrait permettre de repérer les patients susceptibles de présenter une dysfonction systolique inaugurale du VD ou une insuffisance cardiaque droite inaugurale, ce qui ouvre la voie à des interventions en amont visant à prévenir les résultats défavorables pour ces patients.

9.
SICOT J ; 9: 31, 2023.
Article in English | MEDLINE | ID: mdl-37921612

ABSTRACT

Bilateral spontaneous quadriceps tendon rupture is a rare condition characterized by the simultaneous tear of the fibrous tissue connecting the quadriceps muscle to the patella bone. Prompt diagnosis is crucial for appropriate treatment and optimal outcomes. We present a case of a 70-year-old male with bilateral knee pain and an inability to walk, resulting from a trivial fall. Despite initial misdiagnosis, a thorough evaluation, including physical examination and imaging, revealed bilateral quadriceps tendon rupture. Surgical repair was performed, followed by a comprehensive rehabilitation program. At the four-month follow-up, the patient showed significant improvement in pain and function. This article provides a comprehensive review of the existing literature on bilateral quadriceps tendon rupture, emphasizing the challenges in the diagnosis and management of this rare condition. Early diagnosis, prompt surgical intervention, and a tailored rehabilitation program are crucial for successful outcomes.

10.
Prev Med Rep ; 36: 102444, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37840590

ABSTRACT

This population-based study investigated the association of BMI and other predictors with gestational diabetes mellitus (GDM) among Australian Aboriginal and non-Aboriginal mothers. We conducted a state-wide retrospective cohort study that included all singleton births in Western Australia (n = 134,552) between 2012 and 2015 using population health datasets linked by the Western Australian Data Linkage Branch. Associations between GDM and its predictors were estimated as adjusted relative risks (aRRs) from multivariable generalised linear models. Adjusted ratio of relative risks (aRRRs) compared RRs in Aboriginal and non-Aboriginal mothers. Adjusted population attributable fractions estimated the contribution of overweight/obesity to GDM burden, and adjusted predicted probabilities for GDM were plotted against BMI levels. The following predictors had stronger associations with GDM in Aboriginal, compared to non-Aboriginal, mothers: maternal obesity (aRR [95% CI] 3.16 [2.54-3.93]; aRRR 1.57 [1.26-1.94]), previous LGA (aRR 1.70 [1.37-2.12]; aRRR 1.41 [1.13-1.76]) and previous macrosomia (birthweight ≥ 4 kg) (aRR 1.55 [1.24-1.94]; aRRR 1.53 [1.22-1.91]). 46.1% (95% CI: 36.6-54.1) of GDM cases in Aboriginal women (23.3% in non-Aboriginal mothers, 95% CI: 21.6-25.1) were attributed to overweight/obesity. Compared to non-Aboriginal mothers, adjusted GDM probabilities were higher at all BMI levels and showed greater increase with BMI. Overweight/obesity is a key driver of GDM among Aboriginal women. Association between BMI and GDM is stronger in Aboriginal, compared to non-Aboriginal, women especially at higher BMI.

11.
Int J Biol Macromol ; 253(Pt 4): 126884, 2023 Dec 31.
Article in English | MEDLINE | ID: mdl-37709221

ABSTRACT

The change of composition of an adsorbent material has been widely used as a method to increase its adsorption capacity, particularly concerning adsorbents made of polysaccharides. Introducing magnetic adsorbents into contaminated water treatment systems is a highly promising strategy, as it promotes the metal ions removal from water. Considering this, gum Arabic (GA) was associated with alginate (Alg), when magnetite nanoparticles were present or absent, to produce beads that were utilised to take up Cu(II), Cd(II), and Pb(II) from aqueous solution. After a complete characterisation (for which Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and swelling were used), the adsorption properties were established using batch and column tests. The magnetic beads (MAlg/GA) demonstrated improved adsorption in comparison with the beads made without magnetite (Alg/GA) under the same conditions. In normal adsorption conditions (pH 6.0, 25 °C, 2.5 g L-1 of adsorbent dosage), the highest uptake capacities recorded for the MAlg/GA beads were: for Cu(II), 1.33 mmol g-1; Cd(II), 1.59 mmol g-1; and for Pb(II), 1.43 mmol g-1. The pseudo-second-order kinetics and Langmuir isotherm models provided good fits for the adsorption of these metals. Overall, ion exchange and physical forces led to the uptake of these metals by both Alg/GA and MAlg/GA; moreover, the functional groups on the beads played crucial roles as binding sites. Additionally, it was observed that flow rates of >2 mL min-1 did not produce noticeable changes in uptake levels over the same flow period. It was found that the efficient eluting agent was HNO3 (0.2 M). In some cases, the metals were not removed fully from the used beads during the first five cycles of regeneration and reuse. The results of this investigation show that these beads are efficient adsorbents for the removal of metal ions from spiked well water samples.


Subject(s)
Copper , Water Pollutants, Chemical , Copper/chemistry , Cadmium/chemistry , Adsorption , Alginates/chemistry , Lead , Water Pollutants, Chemical/chemistry , Magnetic Phenomena , Ions , Kinetics , Hydrogen-Ion Concentration
14.
Opt Express ; 31(18): 29558-29572, 2023 Aug 28.
Article in English | MEDLINE | ID: mdl-37710753

ABSTRACT

We demonstrate an injection-seeded thin-disk Yb:YAG laser at 1030 nm, stabilized by the Pound-Drever-Hall (PDH) method. We modified the PDH scheme to obtain an error signal free from Trojan locking points, which allowed robust re-locking of the laser and reliable long-term operation. The single-frequency pulses have 50 mJ energy (limited to avoid laser-induced damage) with a beam quality of M2 < 1.1 and an adjustable length of 55-110 ns. Heterodyne measurements confirmed a spectral linewidth of 3.7 MHz. The short pulse build-up time (850 ns) makes this laser suitable for laser spectroscopy of muonic hydrogen, pursued by the CREMA collaboration.

15.
Int J Epidemiol ; 52(5): 1400-1413, 2023 10 05.
Article in English | MEDLINE | ID: mdl-37263617

ABSTRACT

BACKGROUND: Aboriginal and Torres Strait Islander (hereafter Aboriginal) women have a high prevalence of diabetes in pregnancy (DIP), which includes pre-gestational diabetes mellitus (PGDM) and gestational diabetes mellitus (GDM). We aimed to characterize the impact of DIP in babies born to Aboriginal mothers. METHODS: A retrospective cohort study, using routinely collected linked health data that included all singleton births (N = 510 761) in Western Australia between 1998 and 2015. Stratified by Aboriginal status, generalized linear mixed models quantified the impact of DIP on neonatal outcomes, estimating relative risks (RRs) with 95% CIs. Ratio of RRs (RRRs) examined whether RRs differed between Aboriginal and non-Aboriginal populations. RESULTS: Exposure to DIP increased the risk of adverse outcomes to a greater extent in Aboriginal babies. PGDM heightened the risk of large for gestational age (LGA) (RR: 4.10, 95% CI: 3.56-4.72; RRR: 1.25, 95% CI: 1.09-1.43), macrosomia (RR: 2.03, 95% CI: 1.67-2.48; RRR: 1.39, 95% CI: 1.14-1.69), shoulder dystocia (RR: 4.51, 95% CI: 3.14-6.49; RRR: 2.19, 95% CI: 1.44-3.33) and major congenital anomalies (RR: 2.14, 95% CI: 1.68-2.74; RRR: 1.62, 95% CI: 1.24-2.10). GDM increased the risk of LGA (RR: 2.63, 95% CI: 2.36-2.94; RRR: 2.00, 95% CI: 1.80-2.22), macrosomia (RR: 1.95, 95% CI: 1.72-2.21; RRR: 2.27, 95% CI: 2.01-2.56) and shoulder dystocia (RR: 2.78, 95% CI: 2.12-3.63; RRR: 2.11, 95% CI: 1.61-2.77). Birthweight mediated about half of the DIP effect on shoulder dystocia only in the Aboriginal babies. CONCLUSIONS: DIP differentially increased the risks of fetal overgrowth, shoulder dystocia and congenital anomalies in Aboriginal babies. Improving care for Aboriginal women with diabetes and further research on preventing shoulder dystocia among these women can reduce the disparities.


Subject(s)
Diabetes, Gestational , Pregnancy Complications , Pregnancy in Diabetics , Female , Humans , Infant, Newborn , Pregnancy , Diabetes, Gestational/epidemiology , Fetal Macrosomia/epidemiology , Pregnancy in Diabetics/epidemiology , Retrospective Studies , Shoulder Dystocia , Western Australia/epidemiology , Australian Aboriginal and Torres Strait Islander Peoples , Pregnancy Complications/ethnology , Pregnancy Outcome
16.
Am Heart J ; 263: 141-150, 2023 09.
Article in English | MEDLINE | ID: mdl-37271358

ABSTRACT

BACKGROUND: Adults with repaired tetralogy of Fallot (TOF) have right atrial (RA) remodeling and dysfunction, and RA function can be measured using speckle tracking echocardiography. There are limited data about the role of RA strain imaging for risk stratification in this population. We hypothesized that RA reservoir strain can identify TOF patients at risk of developing atrial arrhythmia. To test this hypothesis, we assessed the relationship between RA reservoir strain and atrial arrhythmias in adults with repaired TOF. METHOD: Retrospective cohort study of adults with repaired TOF, and no prior history of atrial arrhythmias. Atrial arrhythmia was defined as atrial fibrillation, atrial flutter/atrial tachycardia, and categorized as new-onset versus recurrent atrial arrhythmias. RESULTS: We identified 426 patients (age 33 ± 12 years; males 208 (49%)) that met the inclusion criteria. The mean RA reservoir strain, conduit strain, and booster strain were 34 ± 11%, 20 ± 9%, and 15 ± 12%, respectively. Of 426 patients, 73 (17%) developed new-onset atrial arrhythmias (atrial flutter/tachycardia n = 42; atrial fibrillation n = 31); annual incidence 1.9%. RA reservoir strain was associated with new-onset atrial arrhythmias (adjusted HR 0.95, 95% CI 0.93-0.97) after multivariable adjustment. Of 73 patients with new-onset atrial arrhythmia, 41 (56%) had recurrent atrial arrhythmia (atrial flutter/tachycardia n = 18; atrial fibrillation n = 23); annual incidence 11.2%. Similarly, RA reservoir strain was associated with recurrent atrial arrhythmias (adjusted HR 0.92, 95% CI 0.88-0.96) after multivariable adjustment. CONCLUSIONS: RA strain indices can identify patients at risk for atrial arrhythmias, and this can in turn, be used to guide the type/intensity of therapy in such patients.


Subject(s)
Atrial Fibrillation , Atrial Flutter , Tachycardia, Supraventricular , Tetralogy of Fallot , Male , Humans , Adult , Young Adult , Middle Aged , Atrial Fibrillation/epidemiology , Atrial Fibrillation/etiology , Atrial Fibrillation/therapy , Atrial Flutter/epidemiology , Atrial Flutter/etiology , Atrial Flutter/therapy , Tetralogy of Fallot/complications , Tetralogy of Fallot/surgery , Retrospective Studies , Tachycardia
17.
Opt Express ; 31(12): 19392-19403, 2023 Jun 05.
Article in English | MEDLINE | ID: mdl-37381355

ABSTRACT

We present an easy-to-implement and low-cost setup for the precise measurement of the period chirp of diffraction gratings offering a resolution of 15 pm and reasonable scan speeds of 2 seconds per measurement point. The principle of the measurement is illustrated on the example of two different pulse compression gratings, one fabricated by laser interference lithography (LIL) and the other by scanning beam interference lithography (SBIL). A period chirp of 0.22 pm/mm2 at a nominal period of 610 nm was measured for the grating fabricated with LIL, whereas no chirp was observed for the grating fabricated by SBIL, which had a nominal period of 586.2 nm.

18.
Opt Express ; 31(4): 5334-5346, 2023 Feb 13.
Article in English | MEDLINE | ID: mdl-36823816

ABSTRACT

We present a general analytical model for the calculation of the spatial distribution of the grating period, enabling the unification of all configurations of classical laser interference lithography (LIL) and scanning-beam interference lithography (SBIL) into one formalism. This is possible due to the consideration of Gaussian beams instead of point sources which allow for the accurate description of not only the laser's far-field but also its near-field. The proposed model enables the calculation of the grating period, the inclination and the slant of the grating lines on arbitrarily shaped substrates, originating from the interference of arbitrarily orientated and positioned Gaussian beams.

19.
Rev Sci Instrum ; 94(1): 013001, 2023 Jan 01.
Article in English | MEDLINE | ID: mdl-36725577

ABSTRACT

The Pound-Drever-Hall (PDH) technique is a popular method for stabilizing the frequency of a laser to a stable optical resonator or, vice versa, the length of a resonator to the frequency of a stable laser. We propose a refinement of the technique yielding an "infinite" dynamic (capture) range so that a resonator is correctly locked to the seed frequency, even after large perturbations. The stable but off-resonant lock points (also called Trojan operating points), present in conventional PDH error signals, are removed by phase modulating the seed laser at a frequency corresponding to half the free spectral range of the resonator. We verify the robustness of our scheme experimentally by realizing an injection-seeded Yb:YAG thin-disk laser. We also give an analytical formulation of the PDH error signal for arbitrary modulation frequencies and discuss the parameter range for which our PDH locking scheme guarantees correct locking. Our scheme is simple as it does not require additional electronics apart from the standard PDH setup and is particularly suited to realize injection-seeded lasers and injection-seeded optical parametric oscillators.

20.
Opt Express ; 31(1): 371-380, 2023 Jan 02.
Article in English | MEDLINE | ID: mdl-36606973

ABSTRACT

Gratings produced by two-spherical-beam Laser Interference Lithography (LIL) will have a nonuniform period, and the associated period variation is larger with the increase of the substrate size. This work quantitatively investigates a noninvasive method for improving the period variation on 4-inch silicon wafers. By temporarily deforming the flexible silicon wafer using a customized concave vacuum chuck [J. Vac. Sci. Technol. B19(6), 2347 (2001)10.1116/1.1421558], we show that the fabricated gratings will have improved period uniformity, with the period variation reduced by 86% at the 1000 nm central grating period setting. This process is a simple and efficient way to achieve linear gratings without altering the LIL configuration with two spherical beams. We present experimental results on the impact of a concave vacuum chuck on the chirp reduction at different grating period settings. Then, we compare two different LIL configurations with different wavelength sources concerning their influence on the efficiency of period variation reduction. Finally, the flatness of the 4-inch silicon wafers due to the temporary bending process is verified using optical profilometry measurements.

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