Wandering principal optical axes in van der Waals triclinic materials.

Nature is abundant in material platforms with anisotropic permittivities arising from symmetry reduction that feature a variety of extraordinary optical effects. Principal optical axes are essential characteristics for these effects that define light-matter interaction. Their orientation - an orthogonal Cartesian basis that diagonalizes the permittivity tensor, is often assumed stationary. Here, we show that the low-symmetry triclinic crystalline structure of van der Waals rhenium disulfide and rhenium diselenide is characterized by wandering principal optical axes in the space-wavelength domain with above π/2 degree of rotation for in-plane components. In turn, this leads to wavelength-switchable propagation directions of their waveguide modes. The physical origin of wandering principal optical axes is explained using a multi-exciton phenomenological model and ab initio calculations. We envision that the wandering principal optical axes of the investigated low-symmetry triclinic van der Waals crystals offer a platform for unexplored anisotropic phenomena and nanophotonic applications.

van der Waals Materials for Overcoming Fundamental Limitations in Photonic Integrated Circuitry.

With the advance of on-chip nanophotonics, there is a high demand for high-refractive-index and low-loss materials. Currently, this technology is dominated by silicon, but van der Waals (vdW) materials with a high refractive index can offer a very advanced alternative. Still, up to now, it was not clear if the optical anisotropy perpendicular to the layers might be a hindering factor for the development of vdW nanophotonics. Here, we studied WS2-based waveguides in terms of their optical properties and, particularly, in terms of possible crosstalk distance. Surprisingly, we discovered that the low refractive index in the direction perpendicular to the atomic layers improves the characteristics of such devices, mainly due to expanding the range of parameters at which single-mode propagation can be achieved. Thus, using anisotropic materials offers new opportunities and novel control knobs when designing nanophotonic devices.

Dual-Band Coupling of Phonon and Surface Plasmon Polaritons with Vibrational and Electronic Excitations in Molecules.

Strong coupling (SC) between light and matter excitations bears intriguing potential for manipulating material properties. Typically, SC has been achieved between mid-infrared (mid-IR) light and molecular vibrations or between visible light and excitons. However, simultaneously achieving SC in both frequency bands remains unexplored. Here, we introduce polaritonic nanoresonators (formed by h-BN layers on Al ribbons) hosting surface plasmon polaritons (SPPs) at visible frequencies and phonon polaritons (PhPs) at mid-IR frequencies, which simultaneously couple to excitons and molecular vibrations in an adjacent layer of CoPc molecules, respectively. Employing near-field optical nanoscopy, we demonstrate the colocalization of near fields at both visible and mid-IR frequencies. Far-field transmission spectroscopy of the nanoresonator structure covered with a layer of CoPc molecules shows clear mode splittings in both frequency ranges, revealing simultaneous SPP-exciton and PhP-vibron coupling. Dual-band SC may offer potential for manipulating coupling between exciton and molecular vibration in future optoelectronics, nanophotonics, and quantum information applications.

Late dislocation of the capsular bag-intraocular lens-modified capsular tension ring complex after knotless transscleral suturing using 9-0 polypropylene.

We report a case of late breakage of a 9-0 polypropylene transscleral suture used for fixation of a dislocated capsular bag-intraocular lens-modified capsular tension ring complex in a 52-year-old woman with Marfan syndrome. Breakage occurred despite use of a cow-hitch technique for external and internal fixation. We believe breakage was caused by the suture chafing on the sharp edges of the modified capsular tension ring eyelet. Cross-sectional analysis of Malyugin-modified capsular tension rings from two different manufacturers revealed a difference with respect to radius of curvature. Suturing intraocular implants with relatively sharp edges may cause suture breakage; further studies are needed to identify the critical parameters for the surface quality of sutured intraocular implants.

Five-year results of non-penetrating deep sclerectomy with demineralized cancellous bone xenogenically derived collagen glaucoma implant.

PURPOSE: To investigate the long-term effectiveness of non-penetrating deep sclerectomy (NPDS) with xenogenically derived cancellous bone collagen glaucoma implant (XCB-CGI) implantation in patients with primary open-angle glaucoma (POAG). MATERIALS AND METHODS: Retrospective chart review of patients with POAG stages 2 and 3 was treated with NPDS and XCB-CGI. Follow-up was at 6 months, 1, 2, 3, 4 and 5 years after surgery. Main outcomes were intraocular pressure (IOP) and medication burden. Secondary outcomes were visual acuity, corneal hysteresis (CH), visual field (VF) and optical coherence tomography (OCT) parameter analysis. RESULTS: Among 71 patients (71 eyes), the mean age was 72.7 ± 9.8. Average initial IOP was 27.7 ± 7.9 and average initial med load was 2.36 ± 0.99. At 6 months, 1, 2, 3, 4 and 5 years, the average IOP was 14.9 ± 3.3 mm Hg (46.2% reduction), 15.3 ± 4.0 mm Hg (44.7% reduction), 14.2 ± 3.8 mm Hg (48.7% reduction), 15.2 ± 3.3 mm Hg (45.0% reduction), 15.5 ± 3.3 mm Hg (44.0% reduction) and 14.2 ± 2.8 mm Hg (48.7% reduction), respectively. In 5 years, the success rate was 34% and 67%, without, and with medications (1.8 ± 0.8 meds required), respectively. Visual acuity was not significantly different (P > .05) at all follow-up visits from baseline. Mean CH increased by 2.1 ± 0.8 (P = .05). No glaucomatous deterioration of the VF and OCT parameters was detected in 56 eyes at the 5-year follow-up. CONCLUSION: NPDS with XCB-CGI implantation is an effective procedure to normalize the level of IOP, stabilize glaucomatous changes and decrease the number of meds needed for glaucoma control.

Graphene-Supported Thin Metal Films for Nanophotonics and Optoelectronics.

Graphene-metal hybrid nanostructures have attracted considerable attention due to their potential applications in nanophotonics and optoelectronics. The output characteristics of devices based on such nanostructures largely depend on the properties of the metals. Here, we study the optical, electrical and structural properties of continuous thin gold and copper films grown by electron beam evaporation on monolayer graphene transferred onto silicon dioxide substrates. We find that the presence of graphene has a significant effect on optical losses and electrical resistance, both for thin gold and copper films. Furthermore, the growth kinetics of gold and copper films vary greatly; in particular, we found here a significant dependence of the properties of thin copper films on the deposition rate, unlike gold films. Our work provides new data on the optical properties of gold and copper, which should be considered in modeling and designing devices with graphene-metal nanolayers.

Femtosecond Laser-Assisted Intraocular Lens Fragmentation: Low Energy Transection.

PURPOSE: To describe a case of femtosecond laser-assisted hydrophobic intraocular lens transection. METHODS: Case report. RESULTS: Femtosecond laser-assisted transection of a one-piece acrylic hydrophobic intraocular lens for explantation via a small surgical incision was successfully performed with low energy parameters. CONCLUSIONS: This case illustrates a novel and effective clinical application of the femtosecond laser. [J Refract Surg. 2017;33(9):646-648.].

Ultralow-Loss CMOS Copper Plasmonic Waveguides.

Surface plasmon polaritons can give a unique opportunity to manipulate light at a scale well below the diffraction limit reducing the size of optical components down to that of nanoelectronic circuits. At the same time, plasmonics is mostly based on noble metals, which are not compatible with microelectronics manufacturing technologies. This prevents plasmonic components from integration with both silicon photonics and silicon microelectronics. Here, we demonstrate ultralow-loss copper plasmonic waveguides fabricated in a simple complementary metal-oxide semiconductor (CMOS) compatible process, which can outperform gold plasmonic waveguides simultaneously providing long (>40 µm) propagation length and deep subwavelength (∼λ(2)/50, where λ is the free-space wavelength) mode confinement in the telecommunication spectral range. These results create the backbone for the development of a CMOS plasmonic platform and its integration in future electronic chips.