Gigahertz-rate-switchable wavefront shaping through integration of metasurfaces with photonic integrated circuit

Achieving spatiotemporal control of light at high-speeds presents immense possibilities for various applications in communication, computation, metrology, and sensing. The integration of subwavelength metasurfaces and optical waveguides offers a promising approach to manipulate light across multiple degrees of freedom at high-speed in compact photonic integrated circuit (PICs) devices. Here, we demonstrate a gigahertz-rate-switchable wavefront shaping by integrating metasurface, lithium niobite on insulator (LNOI) photonic waveguide and electrodes within a PIC device. As proofs of concept, we showcase the generation of a focus beam with reconfigurable arbitrary polarizations, switchable focusing with lateral focal positions and focal length, orbital angular momentum light beams (OAMs) as well as Bessel beams. Our measurements indicate modulation speeds of up to gigahertz rate. This integrated platform offers a versatile and efficient means of controlling light field at high-speed within a compact system, paving the way for potential applications in optical communication, computation, sensing, and imaging

Clinical Efficacy and Rehabilitation of Microscopic “Over the Top” for Bilateral Decompression in Degenerative Lumbar Stenosis: A Retrospective Study

Background. Recently, “over the top” (also called ULBD; microscopic unilateral laminotomy for bilateral decompression) is a less invasive technique for symptomatic degenerative lumbar spinal stenosis (LSS), and this minimally invasive surgical technique has demonstrated favorable therapeutic outcomes. However, the risk of postoperative complications remains controversial. Objective. This study is aimed at determining the clinical efficacy and complication and rehabilitation of the microscopic “over the top” for degenerative LSS in geriatric patients. Study Design. This was a retrospective study. Setting. All data were obtained from the People’s Hospital of a University. Methods. A retrospective analysis of 39 consecutive elderly patients treated for LSS by microscopic “over the top” between January 2016 and January 2018 was performed. A postoperative rehabilitation program for geriatric patients with restricted weight-bearing was instituted after the microscopic “over the top” treatment. Estimated blood loss, duration of operation, length of hospitalization, and total complications were also evaluated. The CT and MRI examinations of the lumbar spine were collected to evaluate the completeness of the nerve decompression. Clinical data were assessed at 6 months and 12 months after operation utilizing the visual analog scale (VAS), Oswestry Disability Index (ODI), and 36-Item Short-Form Health Survey (SF-36). Preoperative comorbidities, complications, and revision surgery were also recorded. Results. We enrolled a total of 39 degenerative LSS patients (27 male and 12 female patients, mean age of 75.8±9.2 years). Twenty patients had one-level of degenerative LSS; thirteen patients had two-level of LSS; six patients had three-level of LSS. The average follow-up time in our study was 14.6±7.8 months (range, 6-24 months). The overall complication rate was 10.2% (4/39), and the reoperation rates at one year were 2.5% (1/39). VAS back and leg pain score at 6 months were decreased to 1.8±0.7 and 1.4±0.6, respectively, and remained at 1.9±0.3 and 1.2±0.2 at 12 months, respectively. ODI scores improved significantly from 32.26±6.82 to 11.44±2.50 at 6 months and 10.56±2.29 at 12 months. 36-Item Short-Form Health Survey scores revealed a significant improvement throughout follow-up. Postoperative complications included dural tear (n=2), neurologic deficit (n=1), and reoperation (n=1). No infections or hematomas were reported. Limitation. Multicenter research is recommended to confirm our results and investigate the factors related to clinical and radiographic results. Conclusions. Microscopic “over the top” technique is a safe, effective option in the therapy of degenerative LSS and obtained satisfactory functional outcomes when coupled with aggressive rehabilitation, with a long recurrence-free recovery