Notes

Surgical results of children with medulloblastoma: the retrospective review of the 405-patient sequence coming from Children's Cancer Healthcare facility Egypt (CCHE-57357).
Surface grating couplers are fundamental building blocks for coupling the light between optical fibers and integrated photonic devices. However, the operational bandwidth of conventional grating couplers is intrinsically limited by their wavelength-dependent radiation angle. The few dual-band grating couplers that have been experimentally demonstrated exhibit low coupling efficiencies and rely on complex fabrication processes. Here we demonstrate for the first time, to the best of our knowledge, the realization of an efficient dual-band grating coupler fabricated using 193 nm deep-ultraviolet lithography for 10 Gbit symmetric passive optical networks. The footprint of the device is 17×10µm2. We measured coupling efficiencies of -4.9 and -5.2dB with a 3-dB bandwidth of 27 and 56 nm at the wavelengths of 1270 and 1577 nm, corresponding to the upstream and downstream channels, respectively.Using a simplified hydrodynamic model of the free electron gas of a metal, we theoretically investigate optically induced DC current loops in a plasmonic nanostructure. Such current loops originate from an optical rectification process relying on three electromotive forces, one of which arises from an optical spin-orbit interaction. The resulting static magnetic field is found to be maximum and dramatically confined at the corners of the plasmonic nanostructure, which reveals the ability of metallic discontinuities to concentrate and tailor static magnetic fields on the nanoscale. Plasmonics can thus generate and tune static magnetic fields and strong magnetic forces on the nanoscale, potentially impacting small scale magnetic tweezing and sensing as well as the generation of magneto-optical effects and spin waves.In this work, we report on the design, fabrication, and characterization of integrated ultracompact polarizers of a recently proposed type based on bent coupled optical waveguides. The devices have been implemented using deep etched silicon nitride waveguides and employing only basic standard fabrication steps.We propose a new type of a mid-infrared ultra-compact optical modulator composed of a graphene metasurface. Unlike the previously proposed schemes based on loss variation of materials or interference, the proposed one utilizes the unique topological characteristic of the isofrequency contour in the hyperbolic metasurface to modulate the transmission. The designed modulator provides a modulation depth of 10.7 dB, the length of which is 750 nm, corresponding to ∼1/30 of an operating wavelength.This publisher's note contains corrections to Opt. Lett.46, 290 (2021)OPLEDP0146-959210.1364/OL.412229.We demonstrate operation of a mid-infrared dysprosium-doped fiber laser with emission at 3388 nm, representing the longest wavelength yet achieved from this class of laser, to the best of our knowledge. Oscillation far removed from the Dy3+ gain peak around 3 µm is achieved through the design of a high feedback optical cavity employing a directly inscribed fiber Bragg grating as the output coupler. Laser performance is characterized by a slope efficiency with respect to injected pump power of 38% and maximum output power of 134 mW, an improvement of at least three orders of magnitude over prior attempts at long wavelength Dy3+ fiber laser operation. This wavelength coincides with a maximum in the absorption coefficient of PMMA, which we exploit for preliminary demonstration of the utility of this source in polymer processing.An analog radio-over-fiber scheme with a high spurious-free dynamic range (SFDR) is proposed for constructing a passive distributed antenna system (DAS). By developing a Lagrange multiplier constrained optimization model, the best trade-off among RF output power, the polarization incident angle, and the RF power ratio is obtained. Consequently, the third-order intermodulation distortion and second-order harmonic distortion can be suppressed simultaneously simply by varying the polarization incident angle. The simulated and experimental results show that the proposed scheme is effective and feasible. Additionally, this Letter offers valuable insights into the nonlinear optimization, and it may be of great significance in future design and manufacture.Mechanical loss of dielectric mirror coatings sets fundamental limits for both gravitational wave detectors and cavity-stabilized optical local oscillators for atomic clocks. Two approaches are used to determine the mechanical loss ringdown measurements of the coating quality factor and direct measurement of the coating thermal noise. Here we report a systematic study of the mirror thermal noise at 4, 16, 124, and 300 K by operating reference cavities at these temperatures. The directly measured thermal noise is used to extract the mechanical loss for SiO2/Ta2O5 coatings, which are compared with previously reported values.We report a switchable and spacing tunable dual-wavelength spatiotemporal mode-locked (STML) laser based on the multimode interference filtering effect in an all-fiber linear cavity. The dual-wavelength STML operations combined with different pulse patterns are achieved. By adjusting the polarization controllers, the dual-wavelength STML pulses can be switched to single wavelength operation, which is tunable up to 35 nm under certain pump powers. Moreover, the dual-wavelength spacing can also be tuned from 8 nm to 22 nm. Navitoclax inhibitor The obtained results contribute to understanding and exploring the spatiotemporal characteristics operating in the multi-wavelength regime of STML fiber lasers. All-fiber STML lasers with lasing wavelength tunability and flexibility may have applications in the fields of optical communications and optical measurements.Second-harmonic generation (SHG) from hyper-Rayleigh scattering (HRS) in a hybrid strong coupling microcavity waveguide (HSCMW) was demonstrated, which indicates a possible method using continuous-wave (cw) incident light. The cw light was coupled into the waveguide with high coupling efficiency by free space coupling technology, and then the electric field intensity of the fundamental wave was enhanced due to local oscillation. HRS occurred by lithium niobite (LN) powder inside the waveguide, resulting in the direct observation of SHG in the transverse direction, with relatively high conversion efficiency measured to be 0.032%/W. This work suggests progress on frequency conversion and is also applicable to other nonlinear processes in a waveguide.
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