Enabling Waveguide Optics in Rhombohedral-Stacked Transition Metal Dichalcogenides with Laser-Patterned Grating Couplers.

Waveguides play a key role in the implementation of on-chip optical elements and, therefore, lie at the heart of integrated photonics. To add the functionalities of layered materials to existing technologies, dedicated fabrication protocols are required. Here, we build on laser writing to pattern grating structures into bulk noncentrosymmetric transition metal dichalcogenides with grooves as sharp as 250 nm. Using thin flakes of 3R-MoS2 that act as waveguides for near-infrared light, we demonstrate the functionality of the grating couplers with two complementary experiments: first, nano-optical imaging is used to visualize transverse electric and magnetic modes, whose directional outcoupling is captured by finite element simulations. Second, waveguide second-harmonic generation is demonstrated by grating-coupling femtosecond pulses into the slabs in which the radiation partially undergoes frequency doubling throughout the propagation. Our work provides a straightforward strategy for laser patterning of van der Waals crystals, demonstrates the feasibility of compact frequency converters, and examines the tuning knobs that enable optimized coupling into layered waveguides.

[Two-stage revision for treatment of periprosthetic infection following hip arthroplasty].

OBJECTIVE: To evaluate the efficacy and optimal re-implantation time of two-stage revision for management of periprosthetic infection following hip arthroplasty. METHODS: We retrospectively analyzed the clinical data of 15 patients (15 hip joints) undergoing two-stage ipsilateral total hip arthroplasty (THA) revision from January, 2006 to January, 2010. In the first stage, after surgical debridement and thorough removal of all the implants, a self-made Vancomycin-loaded cement spacer was implanted. The second stage operation was performed 3-6 months later for debridement and removal of the antibiotic-loaded spacer, followed by re-implantation of Vancomycin-loaded bone cement prosthesis in 9 cases and cementless prosthesis in 6 cases. The patients were followed up for 9-46 months (mean 25 months) after the operation. RESULTS: No reinfection or prosthesis loosening/displacement was found in these cases after the operation. The Harris score increased from 40.3 before the operation to 54.0 after the first-stage operation, and to 88.2 at the last follow-up. CONCLUSION: Two-stage revision is effective for treatment of periprosthetic infection following hip arthroplasty, and 3-6 months can be the optimal interval between the two the first-stage and second-stage operation for re-implantation.