Wavelength-independent coupler from fiber to an on-chip cavity, demonstrated over an 850nm span

A robust wide band (850 nm) fiber coupler to a whispering-gallery cavity with ultra-high quality factor is experimentally demonstrated. The device trades off ideality for broad-band, efficient input coupling. Output coupling efficiency can remain high enough for practical applications wherein pumping and power extraction must occur over very broad wavelength spans

Yb-doped glass microcavity laser operation in water

A ytterbium-doped silica microcavity laser demonstrates stable laser emission while completely submerged in water. To our knowledge, it is the first solid-state laser whose cavity mode interacts with water. The device generates more than 2 μW of output power. The laser performance is presented, and low-concentration biosensing is discussed as a potential application

On-Chip, Ultra-Low Threshold Yb Silica Laser

A novel Yb:SiO_2 fiber-coupled laser on a silicon chip was fabricated using a solution-gel process. We report a record-low pump threshold of 2 μW, and discuss the practical advantages of Yb microlasers

Wavelength-independent bent-fiber coupler to an ultra-high Q cavity demonstrated over 850 nm span

A bent tapered-fiber coupler is experimentally demonstrated to allow wavelength independent fiber-to-cavity coupling over an 850nm span; opening current technology of ultra-high Q cavities for applications spanning the UV to the IR band

Efficient routing of single photons by one atom and a microtoroidal cavity

Single photons from a coherent input are efficiently redirected to a separate output by way of a fiber-coupled microtoroidal cavity interacting with individual Cesium atoms. By operating in an overcoupled regime for the input-output to a tapered fiber, our system functions as a quantum router with high efficiency for photon sorting. Single photons are reflected and excess photons transmitted, as confirmed by observations of photon antibunching (bunching) for the reflected (transmitted) light. Our photon router is robust against large variations of atomic position and input power, with the observed photon antibunching persisting for intracavity photon number 0.03 \lesssim n \lesssim 0.7

A Photon Turnstile Dynamically Regulated by One Atom

Beyond traditional nonlinear optics with large numbers of atoms and photons, qualitatively new phenomena arise in a quantum regime of strong interactions between single atoms and photons. By using a microscopic optical resonator, we achieved such interactions and demonstrated a robust, efficient mechanism for the regulated transport of photons one by one. With critical coupling of the input light, a single atom within the resonator dynamically controls the cavity output conditioned on the photon number at the input, thereby functioning as a photon turnstile. We verified the transformation from a Poissonian to a sub-Poissonian photon stream by photon counting measurements of the input and output fields. The results have applications in quantum information science, including for controlled interactions of single light quanta and for scalable quantum processing on atom chips

Cavity QED with chip-based toroidal microresonators

We report the demonstration of strong coupling between single Cesium atoms and a high-Q chip-based microresonator. Our toroidal microresonators are compact, Si chip-based whispering gallery mode resonators that confine light to small volumes with extremely low losses, and are manufactured in large numbers by standard lithographic techniques. Combined with the capability to couple efficiently light to and from these microresonators by a tapered optical fiber, toroidal microresonators offer a promising avenue towards scalable quantum networks. Experimentally, laser cooled Cs atoms are dropped onto a toroidal microresonator while a probe beam is critically coupled to the cavity mode. When an atom interacts with the cavity, it modifies the resonance spectrum of the cavity, leading to rejection of some of the probe light from the cavity, and thus to an increase in the output power. By observing such transit events while systematically detuning the cavity from the atomic resonance, we determine the maximal accessible single-photon Rabi frequency of Ω0/2π ≈ (100 ± 24) MHz. This value puts our system in the regime of strong coupling, being significantly larger than the dissipation rates in our system

Prenatal phthalate exposures and anogenital distance in Swedish boys

BACKGROUND: Phthalates are used as plasticizers in soft polyvinyl chloride (PVC) and in a large number of consumer products. Because of reported health risks, diisononyl phthalate (DiNP) has been introduced as a replacement for di(2-ethylhexyl) phthalate (DEHP) in soft PVC. This raises concerns because animal data suggest that DiNP may have antiandrogenic properties similar to those of DEHP. The anogenital distance (AGD)-the distance from the anus to the genitals-has been used to assess reproductive toxicity. OBJECTIVE: The objective of this study was to examine the associations between prenatal phthalate exposure and AGD in Swedish infants. METHODS: AGD was measured in 196 boys at 21 months of age, and first-trimester urine was analyzed for 10 phthalate metabolites of DEP (diethyl phthalate), DBP (dibutyl phthalate), DEHP, BBzP (benzylbutyl phthalate), as well as DiNP and creatinine. Data on covariates were collected by questionnaires. RESULTS: The most significant associations were found between the shorter of two AGD measures (anoscrotal distance; AGDas) and DiNP metabolites and strongest for oh-MMeOP [mono(4-methyl-7-hydroxyloctyl) phthalate] and oxo-MMeOP [mono-(2-ethyl-5-oxohexyl) phthalate]. However, the AGDas reduction was small (4%) in relation to more than an interquartile range increase in DiNP exposure. CONCLUSIONS: These findings call into question the safety of substituting DiNP for DEHP in soft PVC, particularly because a shorter male AGD has been shown to relate to male genital birth defects in children and impaired reproductive function in adult males and the fact that human levels of DiNP are increasing globally

Strong Interactions of Single Atoms and Photons near a Dielectric Boundary

Modern research in optical physics has achieved quantum control of strong interactions between a single atom and one photon within the setting of cavity quantum electrodynamics (cQED). However, to move beyond current proof-of-principle experiments involving one or two conventional optical cavities to more complex scalable systems that employ N >> 1 microscopic resonators requires the localization of individual atoms on distance scales < 100 nm from a resonator's surface. In this regime an atom can be strongly coupled to a single intracavity photon while at the same time experiencing significant radiative interactions with the dielectric boundaries of the resonator. Here, we report an initial step into this new regime of cQED by way of real-time detection and high-bandwidth feedback to select and monitor single Cesium atoms localized ~100 nm from the surface of a micro-toroidal optical resonator. We employ strong radiative interactions of atom and cavity field to probe atomic motion through the evanescent field of the resonator. Direct temporal and spectral measurements reveal both the significant role of Casimir-Polder attraction and the manifestly quantum nature of the atom-cavity dynamics. Our work sets the stage for trapping atoms near micro- and nano-scopic optical resonators for applications in quantum information science, including the creation of scalable quantum networks composed of many atom-cavity systems that coherently interact via coherent exchanges of single photons.Comment: 8 pages, 5 figures, Supplemental Information included as ancillary fil

Detecting single viruses and nanoparticles using whispering gallery microlasers

Detection and characterization of individual nano-scale particles, virions, and pathogens are of paramount importance to human health, homeland security, diagnostic and environmental monitoring[1]. There is a strong demand for high-resolution, portable, and cost-effective systems to make label-free detection and measurement of individual nanoparticles, molecules, and viruses [2-6]. Here, we report an easily accessible, real-time and label-free detection method with single nanoparticle resolution that surpasses detection limit of existing micro- and nano-photonic devices. This is achieved by using an ultra-narrow linewidth whispering gallery microlaser, whose lasing line undergoes frequency splitting upon the binding of individual nano-objects. We demonstrate detection of polystyrene and gold nanoparticles as small as 15 nm and 10 nm in radius, respectively, and Influenza A virions by monitoring changes in self-heterodyning beat note of the split lasing modes. Experiments are performed in both air and aqueous environment. The built-in self-heterodyne interferometric method achieved in a microlaser provides a self-reference scheme with extraordinary sensitivity [7,8], and paves the way for detection and spectroscopy of nano-scale objects using micro- and nano-lasers.Comment: Main Text: 14 pages, 5 figures, 27 references. Supplement: 26 pages, 12 figures, 26 reference