Advancing on-chip Kerr optical parametric oscillation towards coherent applications covering the green gap.

Optical parametric oscillation (OPO) in Kerr microresonators can efficiently transfer near-infrared laser light into the visible spectrum. To date, however, chromatic dispersion has mostly limited output wavelengths to >560 nm, and robust access to the whole green light spectrum has not been demonstrated. In fact, wavelengths between 532 nm and 633 nm, commonly referred to as the "green gap", are especially challenging to produce with conventional laser gain.

On-chip Kerr parametric oscillation with integrated heating for enhanced frequency tuning and control.

Nonlinear microresonators can convert light from chip-integrated sources into new wavelengths within the visible and near-infrared spectrum. For most applications, such as the interrogation of quantum systems with specific transition wavelengths, tuning the frequency of converted light is critical. Nonetheless, demonstrations of wavelength conversion have mostly overlooked this metric.

Society for Maternal-Fetal Medicine Position Statement: Extending Medicaid coverage for 12 months postpartum.

Position: The Society for Maternal-Fetal Medicine supports federal and state policies that expand Medicaid eligibility and extend Medicaid coverage through 12 months postpartum to address the maternal morbidity and mortality crisis and improve health equity. Access to coverage is essential to optimize maternal health following pregnancy and childbirth and avoid preventable causes of maternal morbidity and mortality that extend throughout the first year postpartum. The Society opposes policies such as work requirements or limitations on coverage for undocumented individuals that unnecessarily impose restrictions on Medicaid eligibility.

Fourier Synthesis Dispersion Engineering of Photonic Crystal Microrings for Broadband Frequency Combs.

Dispersion engineering of microring resonators is crucial for optical frequency comb applications, to achieve targeted bandwidths and powers of individual comb teeth. However, conventional microrings only present two geometric degrees of freedom - width and thickness - which limits the degree to which dispersion can be controlled. We present a technique where we tune individual resonance frequencies for arbitrary dispersion tailoring.

Kerr-induced synchronization of a cavity soliton to an optical reference.

The phase-coherent frequency division of a stabilized optical reference laser to the microwave domain is made possible by optical-frequency combs (OFCs). OFC-based clockworks lock one comb tooth to a reference laser, which probes a stable atomic transition, usually through an active servo that increases the complexity of the OFC photonic and electronic integration for fieldable clock applications. Here, we demonstrate that the Kerr nonlinearity enables passive, electronics-free synchronization of a microresonator-based dissipative Kerr soliton (DKS) OFC to an externally injected reference laser.

Efficient chip-based optical parametric oscillators from 590 nm to 1150 nm.

Optical parametric oscillators are widely used to generate coherent light at frequencies not accessible by conventional laser gain. However, chip-based parametric oscillators operating in the visible spectrum have suffered from pump-to-signal conversion efficiencies typically less than 0.1 %.

High-performance Kerr microresonator optical parametric oscillator on a silicon chip.

Optical parametric oscillation (OPO) is distinguished by its wavelength access, that is, the ability to flexibly generate coherent light at wavelengths that are dramatically different from the pump laser, and in principle bounded solely by energy conservation between the input pump field and the output signal/idler fields. As society adopts advanced tools in quantum information science, metrology, and sensing, microchip OPO may provide an important path for accessing relevant wavelengths. However, a practical source of coherent light should additionally have high conversion efficiency and high output power.

Conversion Efficiency in Kerr-Microresonator Optical Parametric Oscillators: From Three Modes to Many Modes.

Optical parametric oscillation in a Kerr nonlinear microresonator can generate coherent laser light with frequencies that are widely separated from the pump frequency, allowing, for example, visible light to be generated using a near-infrared pump. To be practically useful, the pump-to-signal conversion efficiency must be far higher than what has been demonstrated in microresonator-based oscillators with widely-separated output frequencies. To address this challenge, here we theoretically and numerically study parametric oscillations in Kerr nonlinear microresonators, revealing an intricate solution space that arises from an interplay of nonlinear processes.

Selective Fetoscopic Laser Photocoagulation or Expectant Management for Stage I Twin-Twin Transfusion: A Cost-Effectiveness Analysis.

Background: Selective fetoscopic laser photocoagulation (SFLP) is the preferred intervention for stage II-IV twin-twin transfusion syndrome (TTTS); however, there is no consensus on whether SFLP or expectant management (EM) is the preferred strategy to manage Quintero stage I TTTS.

Objective: The objective of this study is to estimate whether SFLP or EM is the cost-effective strategy for management of Quintero stage I TTTS.

Study Design: A decision-analysis (DA) model compared SFLP to EM for 1,000 pregnant people with monochorionic-diamniotic twins affected by stage I TTTS.

Priorities and Understanding of Pregnancy Among Women With Congenital Heart Disease: A Mixed-Methods Study.

Background: Many women with congenital heart disease (CHD) desire safe and successful pregnancies, but a significant proportion does not seek prepregnancy counseling.

Objectives: This study aims to distinguish the personal priorities and perceptions about pregnancy in this growing population.

Methods: Women aged 18 to 50 years with CHD were enrolled from 2 sites.

Tectonically-driven oxidant production in the hot biosphere.

Genomic reconstructions of the common ancestor to all life have identified genes involved in HO and O cycling. Commonly dismissed as an artefact of lateral gene transfer after oxygenic photosynthesis evolved, an alternative is a geological source of HO and O on the early Earth. Here, we show that under oxygen-free conditions high concentrations of HO can be released from defects on crushed silicate rocks when water is added and heated to temperatures close to boiling point, but little is released at temperatures <80 °C.

Ultra-broadband Kerr microcomb through soliton spectral translation.

Broadband and low-noise microresonator frequency combs (microcombs) are critical for deployable optical frequency measurements. Here we expand the bandwidth of a microcomb far beyond its anomalous dispersion region on both sides of its spectrum through spectral translation mediated by mixing of a dissipative Kerr soliton and a secondary pump. We introduce the concept of synthetic dispersion to qualitatively capture the system's key physical behavior, in which the second pump enables spectral translation through four-wave mixing Bragg scattering.

Harnessing Dispersion in Soliton Microcombs to Mitigate Thermal Noise.

We explore intrinsic thermal noise in soliton microcombs, revealing thermodynamic correlations induced by nonlinearity and group-velocity dispersion. A suitable dispersion design gives rise to control over thermal-noise transduction from the environment to a soliton microcomb. We present simulations with the Lugiato-Lefever equation (LLE), including temperature as a stochastic variable.

Top Ten Tips Palliative Care Clinicians Should Know About Opioid Use Disorder.

Since the prevalence of substance use disorders, and opioid use disorder (OUD) specifically, remains high and represents a public health crisis, it is critical that palliative care (PC) providers have a broad understanding of this class of chronic, yet treatable, diseases. Conceptualizing stigma associated with OUD, treatment modalities available, and educational opportunities are key factors in providing patient-centered care. A solid foundation of knowledge about OUD in the setting of serious illness is also crucial as PC providers often recommend or prescribe opioids for symptom management in patients who also have OUD.

Direct Kerr frequency comb atomic spectroscopy and stabilization.

Microresonator-based soliton frequency combs, microcombs, have recently emerged to offer low-noise, photonic-chip sources for applications, spanning from timekeeping to optical-frequency synthesis and ranging. Broad optical bandwidth, brightness, coherence, and frequency stability have made frequency combs important to directly probe atoms and molecules, especially in trace gas detection, multiphoton light-atom interactions, and spectroscopy in the extreme ultraviolet. Here, we explore direct microcomb atomic spectroscopy, using a cascaded, two-photon 1529-nm atomic transition in a rubidium micromachined cell.

Thermal and Nonlinear Dissipative-Soliton Dynamics in Kerr-Microresonator Frequency Combs.

We explore the dynamical response of dissipative Kerr solitons to changes in pump power and detuning and show how thermal and nonlinear processes couple these parameters to the frequency-comb degrees of freedom. Our experiments are enabled by a Pound-Drever-Hall (PDH) stabilization approach that provides on-demand, radio-frequency control of the frequency comb. PDH locking not only guides Kerr-soliton formation from a cold microresonator but opens a path to decouple the repetition and carrier-envelope-offset frequencies.

Interlocking Kerr-microresonator frequency combs for microwave to optical synthesis.

We report accurate phase stabilization of an interlocking pair of Kerr-microresonator frequency combs. The two combs, one based on silicon nitride and one on silica, feature nearly harmonic repetition frequencies and can be generated with one laser. The silicon-nitride comb supports an ultrafast-laser regime with three-optical-cycle, 1-picosecond-period soliton pulses and a total dispersive-wave-enhanced bandwidth of 170 THz, while providing a stable phase-link between optical and microwave frequencies.

An optical-frequency synthesizer using integrated photonics.

Optical-frequency synthesizers, which generate frequency-stable light from a single microwave-frequency reference, are revolutionizing ultrafast science and metrology, but their size, power requirement and cost need to be reduced if they are to be more widely used. Integrated-photonics microchips can be used in high-coherence applications, such as data transmission , highly optimized physical sensors and harnessing quantum states , to lower cost and increase efficiency and portability. Here we describe a method for synthesizing the absolute frequency of a lightwave signal, using integrated photonics to create a phase-coherent microwave-to-optical link.

Identifying risk factors for blindness from primary open-angle glaucoma by race: a case-control study.

Purpose: To examine the factors associated with blindness from primary open-angle glaucoma (POAG) among black and white patients at our institution.

Patients And Methods: For this retrospective, case-control study, patients legally blind from POAG ("cases") were matched on age, race, and gender with non-blind POAG patients ("controls"). Thirty-seven black case-control pairs and 19 white case-control pairs were included in this study.

Relationship Between Race, Insurance Coverage, and Visual Acuity at the Time of Cataract Surgery.

Objective: To assess the relationship between sociodemographic variables (including race, age, and insurance coverage) and preoperative best-corrected visual acuity (BCVA) at the time of first-eye cataract surgery.

Methods: Single-center retrospective chart review study at Shiley Eye Institute, University of California, San Diego (UCSD). Medical record data from 600 patients were collected from the appointment immediately preceding cataract surgery, including BCVA in the operated eye converted to the logarithmic minimal angle of resolution (logMAR), insurance coverage, race, sex, age, body mass index, smoking status (including pack years), systemic and ocular comorbidities, and ocular surgical history.

Stably accessing octave-spanning microresonator frequency combs in the soliton regime.

Microresonator frequency combs can be an enabling technology for optical frequency synthesis and timekeeping in low size, weight, and power architectures. Such systems require comb operation in low-noise, phase-coherent states such as solitons, with broad spectral bandwidths (e.g.