Gain Profile Research Articles

Experimental Studies Into the Beam Parameter Product of GaAs High-Power Diode Lasers

Experimental studies into the beam parameter product (BPP) of 940-980 nm GaAs-based high-power diode lasers are presented. Such lasers exhibit broadening far field and narrowing near field with increasing bias, with BPP increasing tenfold over the diffraction limit. First, spectrally-resolved beam profile measurements of lasers with monolithically-integrated gratings are presented, showing that a reproducible series of spatially-extended optical modes makes up the optical field. Then, changes to the device construction are presented, enabling effects limiting BPP to be inferred and addressed. Process- and package-induced effects can be minimized by design, while the effects of carrier, gain and temperature profiles dominate. Self-heating within the laser stripe raises the refractive index, forming a thermal lens, and the variation in curvature of this lens with bias and device construction directly affects BPP. Temperature non-uniformity along the resonator is also shown to strongly degrade BPP. Moreover, current spreading and the resulting lateral carrier accumulation (LCA) amplify high-order, high-BPP modes, thus degrading BPP for any given thermal lens. This LCA-induced degradation is shown to be suppressed by regrown lateral current-blocking structures. Finally, a flatter thermal lens and lower BPP can be achieved using thermal engineering, via changes to the epitaxial design or device layout.

Metabolic Phenotyping in Mice with NASH Using Indirect Calorimetry.

Obesity caused by caloric overload has assumed epidemic proportions. Obesity is frequently associated with metabolic dysfunctions, such as type 2 diabetes, non-alcoholic steatohepatitis (NASH), cardiovascular diseases, and cancer. Metabolic phenotyping is a set of techniques for studying metabolic dysfunction and behavior information including energy expenditure, body weight gain, glucose homeostasis, and lipid profile. Among different metabolic phenotyping methods, indirect calorimetry is an indispensable tool for quantifying the energy balance/imbalance in various mouse models, which enables researchers to probe the development of disease and to evaluate the therapeutic benefit from different interventions. In this chapter, we will describe the procedures of metabolic phenotyping using indirect calorimetry in db/db mouse, a metabolic disorder mouse model which develops NASH.

Towards InAs/InP Quantum-Dash Laser-Based Ultra-High Capacity Heterogeneous Optical Networks: A Review

The unprecedented increase in internet traffic witnessed in the last few years has pushed the community to explore heterogeneous optical networks, including free-space-optics (FSO) communication, radio-over-fiber (RoF), wireless (WL), and their convergent hybrid technologies. This stems from the possibility of seamless integration with the existing fiber-optic backhaul networks while providing much-needed flexibility and scalability. Moreover, efficient optical transceivers, particularly light sources in the form of semiconductor laser diodes, are key in meeting the future demands of the next generation green optical access networks. In this respect, InAs/InP Quantum-dash (Qdash) nanostructure-based lasers have shown tremendous progress in the past few years with applications spanning from a wavelength division multiplexed (WDM) optical communication to recently, millimeter-wave (MMW) over fiber networks. This waveguide-based laser diode (LD) has demonstrated a rule-changing broad multi-wavelength lasing emission, thanks to the inherent and wavelength-tunable wide gain profile offered by the Qdash active-gain region covering S- to U-band regions. Moreover, exploiting mode-locking and optical injection locking assisting techniques, highly coherent InAs/InP Qdash comb laser source at 1550 nm and 1610 nm have been respectively realized, thus opening a new paradigm for their potential applications in green optical and 5G access networks. In this work, progress on utilizing InAs/InP Qdash LD, supporting several sub-carriers, in energy-efficient ~1550 nm and ~1610 nm WDM heterogeneous optical networks with single-mode-fibers (SMF) has been highlighted, exhibiting aggregate data rates of 11 – 12 Tb/s by employing a single device, and accommodating PAM4 and higher-order 32-QAM modulation schemes. Moreover, the recent deployment of this LD in the RoF domain, targeting MMW frequency band, for convergent fiber-wireless networks, is also summarized, with demonstrated 25 to >100 GHz MMW beat-tone frequency generates and transmission of up to 24 Gb/s.

Feasibility of hearing aid gain self-adjustment using speech recognition.

Personal hearing devices, such as hearing aids, may be fine-tuned by allowing the users to conduct self-adjustment. Two self-adjustment procedures were developed to collect the listener preferred gains in six octave-frequency bands from 0.25 kHz to 8 kHz. These procedures were designed to allow rapid exploration of a multi-dimensional parameter space using a simple, one-dimensional user control interface (i.e., a programmable knob). The two procedures differ in whether the user interface controls the gains in all frequency bands simultaneously (Procedure A) or only the gain in one frequency band (Procedure B) on a given trial. Monte-Carlo simulations suggested that for both procedures the gain preference identified by simulated listeners rapidly converged to the ground-truth preferred gain profile over the first 20 trials. Initial behavioral evaluations of the self-adjustment procedures, in terms of test-retest reliability, were conducted using 20 young, normal-hearing listeners. Each estimate of the preferred gain profile took less than 20 minutes. The deviation between two separate estimates of the preferred gain profile, conducted at least a week apart, was about 10 dB ~ 15 dB.

Investigation Of Dual-Pump Fiber Optical Parametric Amplifier Performance Driven by Energy Transfer Between Four-Wave Mixing Process

Fiber optical parametric amplifier (FOPA) is operated based on energy transfer from pump waves to signal wave and at the end of the fiber, an idler wave is generated. This process is called four-wave mixing (FWM). Even though effects of higher-order dispersion coefficients, fiber length, fiber nonlinearity, fiber attenuation, pump powers, pump wavelength separation and distance of central pump wavelength with ZDW on gain profiles have been examined by previous researchers, but on different fiber or numerically studied using the Optisys system, analytical model or different amplitude equations. Thus, in this study, the above-mentioned parameters on the gain performance of dual pump fiber optical parametric amplifier (FOPA) using highly nonlinear shifted fiber (HNL-DSF) as a medium will be numerically investigated using ode45 function in Matlab. The gain at a certain wavelength can be obtained by solving 4 coupled amplitude equations with fiber loss and pump depletion that govern the four-wave mixing (FWM) process of pumps, signal and idler waves. Simulations results indicate positive gives poor or no gain, meanwhile, an addition of to negative widens the bandwidth, but there is no significant effect with the addition of . Besides, an increase of fiber length, nonlinearity and pump powers improve gain performance, but an increase of fiber loss decays the gain amplitude. Increment of pump separation will enhance flatness of gain at wavelength far from central wavelength but results in an increase of gain reduction at the central wavelength. Lastly, must be positive, not too small and not bigger than 1.125nm to get a high, broader and lesser ripples gain.

Effect of Beilschmedia obscura on the prevention of high fat/high sucrose diet induced metabolic syndrome on male Albino Wistar rats

IntroductionBeilschmiedia (Lauraceae) is a pantropical genus of about 287 species, distributed in tropical Asia and Africa used in traditional medicines to cure many diseases. This study aimed to explore biological properties of Beilschmiedia obscura (B. obscura) on the prevention and management of metabolic syndrome (MetS) features induced by High Fat/High Sucrose (HF/HS) diet in rats as therapeutic option. MethodsMetS was induced after administration of HF/HS diet followed by administration of B. Obscura powder at 5% or 10% for 21 days, while the control group received a chow diet and distilled water and the positive control group received the HF/HS diet and distilled water. At the end of the experiment, rats were sacrificed; the parameters of lipid profile, markers of oxidative stress, antioxidant status were evaluated. ResultsHF/HS diet successfully induced weight gain, oxidative stress and lipid profile disorders from rats. Treatment with powder of B. obscura at 10% than the 5% showed a reduction of body weight in treated groups and, anti-hyperlipidemic effect by improving lipid profile parameters. Triglycerides, Total cholesterol and LDL cholesterol levels were lower (p<0.05) and HDL-cholesterol levels higher in the treated groups compared to positive control. Inhibition of lipid peroxidation, and improvement protein thiols levels and catalase activity were also observed in treated groups. ConclusionThis study revealed that B. obscura whole plant was efficient in reducing biomarkers involved in metabolic syndrome and could efficiently help in its management by preventive effect.

725 nm watt-level injection-locked continuous-wave Ti:sapphire laser for a mercury optical lattice clock.

We develop a watt-level 725 nm continuous-wave tunable narrow linewidth injection-locked Ti:sapphire laser. The seed laser is frequency-locked on a Fabry-Perot cavity to narrow the linewidth and stabilize the frequency. Because the wavelength of the seed laser is located at the edge of the gain profile of the Ti:sapphire crystal, it is difficult to injection-lock the Ti:sapphire laser at 725 nm. A cavity mirror, which has a long-pass-filter coating with a sharp edge, is used in the Ti:sapphire cavity to suppress mode competition from the long wavelength side. This method effectively reduces the power requirement of the seed laser at 725 nm, and the Ti:sapphire laser can be injection-locked at higher output power. As a result, a 1 W output power with a 27% slope efficiency is achieved in the injection-locked laser, and a 210 mW UV laser is obtained in a subsequent second-harmonic generation stage. To the best of our knowledge, this is the shortest wavelength for the watt-level injection-locked continuous-wave Ti:sapphire laser. This laser will be used in a mercury optical lattice clock in the future.

Ultrafast Lasing Dynamics in a CsPbBr3 Perovskite Microplate

The perovskite microlaser is a competitive candidate of light source for optical communication and integrated photonic circuits. Understanding the fundamental mechanism of lasing is crucial for the upcoming devices. The ultrafast establishment of lasing modes within a 2D perovskite microplate cavity at room temperature is investigated. The transient red shift of lasing modes can be found. Analysis based on electron–hole plasma (EHP) and a dynamic Drude‐like model are carried out with simulations on the transient dielectric response and the mode shift. In addition, the integrated lasing gain profile have a red shift at high excitation intensity, which is explained with EHP‐induced bandgap renormalization. The conflict between the experimental phenomena and the exciton–polariton theory confirms that under intense excitation, the exciton–polariton is ruled out for the origin of lasing. These results provide a direct understanding of the lasing evolving in a 2D perovskite microcavity. Suppressing the EHP‐related transient shift of cavity modes will advance the lasing applications.

Daratumumab, Cyclophosphamide, Bortezomib, Lenalidomide, Dexamethasone (Dara-CVRd), V-Augmented Autologous Stem Cell Transplant (V-ASCT) and Dara-Vrd Consolidation in Ultra-High Risk (UHiR) Newly Diagnosed Myeloma (NDMM) and Primary Plasma Cell Leukemia (pPCL) Compared with Myeloma XI/XI+ Trial Treatment for Uhir MM: The UK Optimum/Muknine Trial

▪Background: Outcomes for patients with ultra-high risk (UHiR) newly diagnosed multiple myeloma (NDMM) and patients with primary plasma cell leukemia (pPCL) remain unsatisfactory with current standard therapies. Traditional comparative trials randomising against a standard of care control arm are thus challenging for patients with UHiR NDMM or pPCL, and novel approaches to address their high unmet need are required. OPTIMUM/MUKnine (NCT03188172) is a ‘digital comparator arm’ trial for UHiR NDMM and pPCL patients with protocol defined outcome comparison against fully molecularly matched UHiR patients from the near-concurrent NCRI Myeloma XI/XI+ trial, the ‘MyXI prior’. We report final analysis of the primary endpoint progression free survival (PFS) at 18 months for patients treated in OPTIMUM with Dara-CVRd induction, V-augmented ASCT and Dara-VRd consolidation, compared to the MyXI prior.Methods: Between Sep 2017 and Jul 2019, 472 patients from 39 UK hospitals with suspected NDMM or pPCL were screened. 107 patients with UHiR NDMM by central trial genetic (≥2 high risk lesions: t(4;14), t(14;16), t(14;20), gain(1q), del(1p), del(17p)) or gene expression SKY92 (SkylineDx) profiling, or with pPCL (circulating plasmablasts >20%) were identified and recruited to OPTIMUM. Patients received up to 6 cycles of Dara-CVRd induction, V-ASCT, followed by Dara-VRd consolidation 1 for 6 cycles (Cons1), Dara-VR consolidation 2 for 12 cycles and monthly Dara-R maintenance until progression. This is the final analysis of the primary trial endpoint progression-free survival (PFS) at 18 months comparing OPTIMUM with the MyXI prior of patients treated with CRd or carfilzomib-CRd (KCRd) induction, ASCT and R maintenance or observation, using a Bayesian framework. Secondary endpoints include PFS, OS, safety and quality of life.Results: At median follow-up of 27.1 months (95% CI 25.1-29.3), median PFS was not reached for OPTIMUM patients. PFS was superior at the pre-specified time point of 18 months for OPTIMUM patients with an estimate of 81.7% (95% CI: 74.2-89.1) versus 65.9% (95% CI: 57.3-74.4) for the MyXI prior (Figure 1). PFS at 18 months was consistently shorter for both CRd (64.5%; 95% CI: 53.8-75.3) and KCRd (68.3%; 95% CI: 54.0-82.5) treated patients compared with OPTIMUM. There was a 99.5% chance of superior PFS outcome with OPTIMUM therapy compared to the MyXI prior within the Bayesian framework; easily surpassing the 85% pre-specified threshold of sufficient evidence of activity. The difference between trial treatments increased over time: 6 month estimates were similar across all treatment arms with OPTIMUM 95.3% (95% CI: 91.3-99.3), MyXI KCRd 95.1% (95% CI: 88.5-100.0), MyXI CRd 93.5% (95% CI: 88.0-99.0), while 12 month estimates were similar for OPTIMUM with 87.5% (95% CI: 81.2-93.9) and MyXI KCRd 87.8% (77.8-97.8), but lower in CRd 81.7% (95% CI: 73.0-90.3). The majority (94%) of patients who started OPTIMUM Cons1 completed all 6 cycles of therapy. Most frequent grade 3/4 adverse events (AEs) during Cons1 included thrombocytopenia (27.9%), neutropenia (21%) and infection (19.8%), however, grade 4 events were rare (<5%) for all categories, consistent with previously presented data on induction. We previously reported high MRD-negativity rates of 61% at day +100 post V-ASCT for OPTIMUM, with a lower rate of 40% of patients showing both complete response (CR) and MRD-neg. With further follow-up, CR rate increased to 68.2% (95% CI: 58.5-76.9) at end of Cons1, including virtually all patients with MRD-neg finding post V-ASCT.Conclusions: OPTIMUM demonstrated a clear PFS benefit at 18 months for intensified Dara combination therapy pre- and post-ASCT for UHiR NDMM and pPCL over the MyXI prior. Improvement of comparative benefit over time suggests particular efficacy of Dara-VRd in maintaining responses post ASCT, a key challenge in UHiR MM. This is, to our knowledge, the first prospective digital comparator trial for MM; central screening of an all-comer population combined with robust, detailed molecular matching maintained reliability and limited biases. These results demonstrate a novel framework for accelerated comparative evidence generation for patients with high unmet clinical need. [Display omitted] DisclosuresKaiser: BMS/Celgene: Consultancy, Other: Travel support, Research Funding; Janssen: Consultancy, Other: Educational support, Research Funding; GSK: Consultancy; Karyopharm: Consultancy, Research Funding; Pfizer: Consultancy; Amgen: Honoraria; Seattle Genetics: Consultancy; Takeda: Consultancy, Other: Educational support; AbbVie: Consultancy. Hall: Janssen: Research Funding; BMS/Celgene: Research Funding. Garg: University Hospital Leicester: Current Employment; Takeda Janssen Novartis Sanofi: Other: Travel Accommodations, Expenses; Amgen Janssen Novartis Sanofi Takeda: Honoraria. Jackson: J and J: Consultancy, Honoraria, Speakers Bureau; GSK: Consultancy, Honoraria, Speakers Bureau; takeda: Consultancy, Honoraria, Research Funding, Speakers Bureau; amgen: Consultancy, Honoraria, Speakers Bureau; celgene BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; oncopeptides: Consultancy; Sanofi: Honoraria, Speakers Bureau. Cook: BMS/Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Sanofi: Consultancy; Karyopharm: Consultancy; Amgen: Consultancy. Pratt: Binding Site: Consultancy; Janssen: Consultancy; Takeda: Consultancy; Amgen: Consultancy; BMS/Celgene: Consultancy; Gilead: Consultancy. Drayson: Abingdon Health: Current holder of individual stocks in a privately-held company. Jenner: Janssen: Consultancy, Honoraria, Speakers Bureau; BMS/Celgene: Consultancy, Honoraria, Speakers Bureau; Pfizer: Consultancy; Takeda: Consultancy.

SNR Optimization of Multi-Span Fiber Optic Communication Systems Employing EDFAs With Non-Flat Gain And Noise Figure

Throughput optimization of optical communication systems is a key challenge for current optical networks. The use of gain-flattening filters (GFFs) simplifies the problem at the cost of insertion loss, higher power consumption and potentially poorer performance. In this work, we propose a component-wise model of a multi-span transmission system for signal-to-noise ratio (SNR) optimization. A machine-learning based model is trained for the gain and noise figure spectral profile of a C-band amplifier without a GFF. The model is combined with the Gaussian noise model for nonlinearities in optical fibers including stimulated Raman scattering and the implementation penalty spectral profile measured in back-to-back in order to predict the SNR in each channel of a multi-span wavelength division multiplexed system. All basic components in the system model are differentiable and allow for the gradient descent-based optimization of a system of arbitrary configuration in terms of number of spans and length per span. When the input power profile is optimized for flat and maximized received SNR per channel, the minimum performance in an arbitrary 3-span experimental system is improved by up to 8 dB w.r.t. a system with flat input power profile. An SNR flatness down to 1.2 dB is simultaneously achieved. The model and optimization methods are used to optimize the performance of an example core network, and 0.2 dB of gain is shown w.r.t. solutions that do not take into account fiber nonlinearities. The method is also shown to be beneficial for systems with ideal gain flattening, achieving up to 0.3 dB of gain w.r.t. a flat input power profile.

Active Mode Switching in Plasmonic Microlasers by Spatial Control of Optical Gain.

The pursuit of miniaturized optical sources for on-chip applications has led to the development of surface plasmon polariton lasers (plasmonic lasers). While applications in spectroscopy and information technology would greatly benefit from the facile and active tuning of the output wavelength from such devices, this topic remains underexplored. Here, we demonstrate optically controlled switching between predefined wavelengths within a plasmonic microlaser. After fabricating Fabry-Pérot plasmonic cavities that consist of two curved block reflectors on an ultrasmooth flat Ag surface, we deposit a thin film of CdSe/CdxZn1-xS/ZnS colloidal core/shell/shell nanoplatelets (NPLs) as the gain medium. Our cavity geometry allows the spatial and energetic separation of transverse modes. By spatially modulating the gain profile within this device, we demonstrate active selection and switching between four transverse modes within a single plasmonic laser. The fast buildup and decay of the plasmonic modes promises picosecond switching times, given sufficiently rapid changes in the structured illumination.

Retinopathy of prematurity: Postnatal weight gain and risk factors profile; a hospital-based study from a tertiary care center

Background: Premature infants often develop blindness in one or both eyes due to disparity in retinal growth. This condition is termed as retinopathy of prematurity (ROP). Aim: The aim of the study is to study the postnatal weight gain pattern of preterm infants (Age &lt; 32 weeks) and risk factors of ROP in a tertiary care center and to validate the lower birth weight and gestational age (GA) for ROP. Methods: Hospital-based study on 110 preterm neonates admitted in the neonatal intensive care unit (NICU) who fulfilled the criteria for ROP screening. On screening, 55 neonates were identified to have ROP and 55 neonates identified to have no ROP. The profiles of ROP and risk factors were documented according to the International Classification for ROP recommendations. The data were analyzed for GA, birth weight, and risk factors predisposing to ROP. Results: A total of 110 preterm neonates were screened, out of which, 55 had ROP. The mean GA (P = 0.002), Apnea (P = 0.001), ventilation (P = 0.001), and surfactant (P = 0.001) were observed a significant difference. Further, a significant difference in weight gain pattern in the two groups (P &lt; 0.05) was also observed. The group without ROP had a better weight gain pattern than the group with ROP. Conclusion: Our study revealed prematurity, low birth weight, and birth weight increasing patterns were found to be strong predictors of ROP. GA, apnea, ventilation, and surfactant were found to be statistically significant factors associated with ROP.

Modulational stability brought by cubic–quartic interactions of the nearest-neighbor in FK model subjected in a parametrized on-site potential

This work extends to higher-order interactions the results of Nguetcho (2017), in which we discussed only on modulational instability in one-dimensional chain made of atoms, harmonically coupled to their nearest neighbors and subjected to an external on-site potential. Here we investigate the competition between cubic–quartic nonlinearities interactions of the nearest-neighbor and substrate’s deformability, and mainly discuss its impact on the modulational instability of the system. This makes it possible to adapt the theoretical model to a real physical system such as atomic chains or DNA lattices. The governing equation, derived from the modified Frenkel–Kontorova model, is an extended nonlinear Schrödinger equation (eNLS) containing a new higher-order nonlinear term. By employing linear stability analysis, the generic properties of the MI gain spectra of the system are demonstrated. In the presence of the new quartic nonlinearity, the combinations of the system’s parameters open a large variety of gain profiles and instability domains that cannot be explored without the quartic nonlinearity. Direct numerical simulations are performed to support our analytical results, and an excellent agreement is found.

A 23 dBm Gain Shaping Stacked Power Block CMOS Power Amplifier Achieving 36% PAE

This paper introduces a design methodology that reduces the fundamental trade-off between linearity and power added efficiency (PAE) in CMOS power amplifier (PA). In our work, a stacked power block (SPB) has been proposed to mitigate the effect of gate–source capacitance (Cgs), thus linearizing the PA. Each stage is biased independently to shape the gain profile, either to be in the expanded mode or in the compressed mode, in which once combined it delivers a flat gain response and confirming the linearity performance. Efficient PI input and output matching networks are proposed to ensure no further distortion, once connected to the 50 Ω source and load. The PA achieves input and output return losses of less than −10 dB from 2.40 to 2.50 GHz. At the center frequency of 2.45 GHz, the SPB-PA achieves a gain of 10 dB and it is unconditionally stable. The proposed gain shaping linearization technique delivers a maximum linear output power (Poutlinmax) of 19.8 dBm with only 3.3 dB back-off from maximum output power (Poutmax) of 23.1 dBm. The SPB-PA meets the WLAN specification with linear PAE of 30% and peak PAE of 36.1%. The proposed SPB-PA reduces the fundamental trade-off between linearity and efficiency. Integration of this PA in wireless SoC shall reduce the chip’s overall power consumption.

An Artificial Magnetic Conductor-Based Wideband Circularly Polarized Antenna with Low-Profile and Enhanced Gain

A broadband circularly polarized (CP) antenna with enhanced gain and low profile is proposed. Two identical dipoles with full wavelength are placed orthogonally to generate radiation waves with equal amplitude and orthogonal polarization. The arms of the dipoles are designed as stepped patches to enlarge the impedance matching bandwidth and axial ratio (AR) bandwidth. Crossed-dipoles with full wavelength are utilized as the main radiators to provide a wide operating bandwidth and enhanced gain, and an artificial magnetic conductor (AMC) structure is introduced as the reflector to reduce the profile of the whole antenna. Due to the introduction of the AMC structure, the antenna profile is reduced from 12.8 to 6.9 mm, that is, reduced to 0.14λ0 (where λ0 denotes the wavelength corresponding to the center frequency of the passband, 4.0–8.5 GHz). A simulation and experiment were carried out to verify the performance of the proposed antenna. Experimental results showed that the antenna realized an impedance bandwidth of 74%, an AR bandwidth of 67.7%, a peak gain of 12.1 dBic, and an average gain of 10.69 dBic.

Use of a Biodegradable, Contrast-Filled Rectal Spacer Balloon in Intensity-Modulated Radiotherapy for Intermediate-Risk Prostate Cancer Patients: Dosimetric Gains in the BioPro-RCMI-1505 Study.

Background/purposeDose-escalated external beam radiotherapy (RT) is effective in the control of prostate cancer but is associated with a greater incidence of rectal adverse events. We assessed the dosimetric gain and safety profile associated with implantation of a new biodegradable rectal spacer balloon.Materials/methodsPatients scheduled for image-guided, intensity-modulated RT for intermediate-risk prostate cancer were prospectively included in the French multicenter BioPro-RCMI-1505 study (NCT02478112). We evaluated the dosimetric gain, implantation feasibility, adverse events (AEs), and prostate-cancer-specific quality of life associated with use of the balloon spacer.ResultsAfter a scheduled review of the initial recruitment target of 50 patients by the study’s independent data monitoring committee (IDMC), a total of 24 patients (including 22 with dosimetry data) were included by a single center between November 2016 and May 2018. The interventional radiologist who implanted the balloons considered that 86% of the procedures were easy. 20 of the 24 patients (83.3%) received IMRT and 4 (16.7%) received volumetric modulated arc therapy (78-80 Gy delivered in 39 fractions). The dosimetric gains associated with spacer implantation were highly significant (p<0.001) for most variables. For the rectum, the median (range) relative gain ranged from 15.4% (-9.2−47.5) for D20cc to 91.4% (36.8−100.0) for V70 Gy (%). 15 patients (62%) experienced an acute grade 1 AE, 8 (33%) experienced a late grade 1 AE, 1 (4.2%) experienced an acute grade 2 AE, and 3 experienced a late grade 2 AE. No grade 3 AEs were reported. Quality of life was good at baseline (except for sexual activity) and did not markedly worsen during RT and up to 24 months afterwards.ConclusionThe use of a biodegradable rectal spacer balloon is safe, effective and associated with dosimetric gains in modern RT for intermediate-risk prostate cancer.

Tm3+-doped calcium lithium tantalum gallium garnet (Tm:CLTGG): novel laser crystal

We report on the development of a novel laser crystal with broadband emission properties at ∼2 µm – a Tm3+,Li+-codoped calcium tantalum gallium garnet (Tm:CLTGG). The crystal is grown by the Czochralski method. Its structure (cubic, sp. gr. I a 3 ¯ d , a = 12.5158(0) Å) is refined by the Rietveld method. Tm:CLTGG exhibits a relatively high thermal conductivity of 4.33 Wm-1K-1. Raman spectroscopy confirms a weak concentration of vacancies due to the charge compensation provided by Li+ codoping. The transition probabilities of Tm3+ ions are determined using the modified Judd-Ofelt theory yielding the intensity parameters Ω2 = 5.185, Ω4 = 0.650, Ω6 = 1.068 [10−20 cm2] and α = 0.171 [10−4 cm]. The crystal-field splitting of the Tm3+ multiplets is revealed at 10 K. The first diode-pumped Tm:CLTGG laser generates 1.08 W at ∼2 µm with a slope efficiency of 23.8%. The Tm3+ ions in CLTGG exhibit significant inhomogeneous spectral broadening due to the structure disorder (a random distribution of Ta5+ and Ga3+ cations over octahedral and tetrahedral lattice sites) leading to smooth and broad gain profiles (bandwidth: 130 nm) extending well above 2 µm and rendering Tm:CLTGG suitable for femtosecond pulse generation.

Wide Impedance-Bandwidth and Gain-Bandwidth Terahertz On-Chip Antenna With Chip-Integrated Dielectric Resonator

A wide impedance-bandwidth and gain-bandwidth terahertz (THz) on-chip antenna (OCA) with chip-integrated dielectric resonator (CIDR) backed by a ground plane is proposed in this article. The antenna uses the inherent silicon substrate in complementary metal-oxide-semiconductor (CMOS) technologies as a rectangular dielectric resonator (DR), that is, the CIDR. This CIDR can be seen as a standard dielectric resonator antenna (DRA) or a magnetic wall cavity with in-phase reflected waves from the ground. A versatile comb-shaped dipole antenna is designed above the silicon CIDR, functioning both as a feeder for the DRA and an independent radiator. With the proper design of the CIDR and the dipole, multiple higher order DR modes and the cavity mode are simultaneously excited, namely, hybrid DR-cavity modes. The hybrid modes greatly expand the bandwidth and improve the gain. Simulations show that the -10 dB impedance bandwidth and 3 dB gain bandwidth are 50% and 34.5%, respectively, while a peak gain of 6.5 dBi is achieved at 305 GHz. For validation, the antenna is fabricated using the Taiwan Semiconductor Manufacturing (TSMC) 65 nm CMOS technology and tested by dedicated THz measurement setups. The fabricated sample shows a peak gain of 8.6 dBi and a maximum radiation efficiency of 44% at 295 GHz. Meanwhile, low cross-polarization levels and stable patterns are also observed. The features of wide bandwidth, high gain, and low profile make the antenna a good candidate in fully integrated THz transceiver systems. To the best of the authors' knowledge, this is the widest fully integrated OCA working at THz frequencies.

Machine Learning Assisted Inverse Design for Ultrafine, Dynamic and Arbitrary Gain Spectrum Shaping of Raman Amplification

Distributed Raman amplifier (DRA) has been widely studied in recent decades because of its low noise figure and flexible gain. In this paper, we present a novel scheme of DRA with broadband amplified spontaneous emission(ASE) source as pump instead of discrete pump lasers. The broadband pump is optimized by machine learning based inverse design and shaped by programmable waveshaper, so as to realize the ultrafine, dynamic and arbitrary gain spectrum shaping of Raman amplification. For the target of flat gain spectrum, the maximum gain flatness of 0.1086 dB is realized based on the simulation results. For the target of arbitrary gain spectrum, we demonstrate four gain profiles with maximum root mean square error (RMSE) of 0.074 dB. To further measure the performance of arbitrary gain spectrum optimization, the probability density functions (PDF) of RMSE and Errormax are presented. Meanwhile, the numeral relationship between the bands of broadband pump and signal is also explored. Furthermore, this work has great application potential to compensate the gain distortion or dynamic change caused by other devices in communication systems.

Limits and Opportunities for Miniaturizing Ultrasonic Surgical Devices Based on a Langevin Transducer.

Minimally invasive surgery offers opportunities for reduced morbidities, faster postoperative recovery, and reduced costs, and is a major focus of surgical device innovation. For ultrasonic surgical devices, which offer benefits of high precision, low force, and tissue selectivity in surgical procedures, there exist laparoscopic ultrasonic shears for minimally invasive surgeries that combine tissue cutting with vessel hemostasis and sealing functions. Another approach to laparoscopy that could enable new procedures, and increase the sites of surgeries that could be reached by an ultrasonic device, involves integrating a miniature ultrasonic tool with a flexible surgical robot. However, miniaturization presents challenges in delivering the ultrasonic vibrational energy required to cut hard and soft tissues, partly due to the concomitant small volume of piezoelectric material. This article aims to provide insights into the trade-offs between transducer size, volume of piezoceramic material, resonance frequency, and the achievable displacement amplitude of devices that, consistent with current ultrasonic surgical tools, are based on a bolted Langevin transducer (BLT) and tip. Different configurations of BLTs are studied, including a cascaded version, simple bar versions, and BLTs with different front mass geometries. Results show that a BLT with a larger number of piezoceramic rings exhibits a higher coupling coefficient [Formula: see text] but with the compromise of a lower mechanical Q and stronger nonlinear response at increasing excitation levels. Displacement amplitude is reduced considerably when a BLT is excited at a higher harmonic, where the PZT rings are maintained at a nodal plane, and the resonance frequency shift at increasing excitation levels increases significantly. The electromechanical and dynamic characteristics of a cascaded transducer excited in its third longitudinal mode (L3) are almost equivalent to a much shorter version of a BLT driven at the same frequency but in its first longitudinal mode (L1), showing that a cascaded BLT can be a realistic proxy for studying the dynamics of small BLT devices. A new figure of merit is proposed that is the product of Q , [Formula: see text], and gain, which [Formula: see text] accounts for the gain of cylindrical BLTs which is shown not to be unity. It also proves effective as it incorporates the key factors affecting the achievable displacement amplitude of a BLT, including for BLTs with gain profiles in the front mass. The order of highest to lowest amplitude of a series of six gain-profile BLTs matches the order estimated by the figure of merit. It is shown that a BLT with a stepped profile front mass can achieve displacement that has the potential to cut hard or soft tissue and exhibits the smallest shifts in resonance frequency at increasing excitation levels.