Flat optical phased array receiver incorporating an on-chip metalens concentrator.

We propose and design a flat optical phased array (OPA) receiver that consists of a grating antenna, a free-propagation region (FPR) incorporating an on-chip metalens concentrator (OCMC), and an output port of a tapered waveguide. By concatenating the OCMC-integrated FPR with the antenna, the proposed OPA allows light coupled at a slanted ψ angle to be conveyed to the output, thereby resolving the challenges of phase-controlled light detection. To impose a space-dependent phase on the incident light from the antenna, the OCMC is constructed by laterally arranging subwavelength slot meta-atoms with varying slot lengths, which are created in the core layer of a slab and uniformly quantized at 16 phase levels.

Highly efficient broadband silicon nitride polarization beam splitter incorporating serially cascaded asymmetric directional couplers.

The implementation of a polarization beam splitter (PBS) on a silicon nitride platform remains challenging owing to its relatively low index. We therefore propose a silicon nitride PBS that exploits serially cascaded asymmetric directional couplers (ADCs), leading to a high polarization extinction ratio (PER) over a broad bandwidth. The ADC spatially routes incident light through polarization-selective mode coupling under a small footprint of 112 µm.

Temporal response of polymer waveguide beam scanner with thermo-optic phase-modulator array.

Solid-state light detection and ranging, capable of performing beam scanning without using any mechanical moving parts, requires a phase-modulator array. Polymers facilitate the fabrication of efficient phase modulators with low drive power, owing to their high thermo-optic (TO) effect and low thermal conductivity. We designed and fabricated a polymeric phase-modulator array and analyzed the temporal response of the TO phase modulator.

Silicon nitride optical phased array based on a grating antenna enabling wavelength-tuned beam steering.

An optical phased array (OPA) in silicon nitride (SiN) is conspicuously highlighted as a vital alternative to its counterpart in silicon. However, a limited number of studies have been conducted on this array in terms of wavelength-tuned beam steering. A SiN OPA has been proposed and implemented with a grating antenna that incorporated an array of shallow-etched waveguides, rendering wavelength-tuned beam steering along the longitudinal direction.

The Relationship between Superior Disc-Endplate Complex Injury and Correction Loss in Young Adult Patients with Thoracolumbar Stable Burst Fracture.

Background: To determine the relationship between superior disc-endplate complex injury and correction loss after surgery in a group of young adult patients with a stable thoracolumbar burst fracture.

Methods: The study group was comprised of young adult patients who had undergone short-segment posterior fixation and bone grafting under the diagnosis of a stable thoracolumbar burst fracture from March 2008 to February 2014. Follow-up was available for more than 1 year.

Radiologic and Clinical Courses of Degenerative Lumbar Scoliosis (10°-25°) after a Short-Segment Fusion.

Study Design: Retrospective study.

Purpose: We report the surgical outcomes of small degenerative lumbar scoliosis (DLS) patients treated by a short-segment fusion and followed for a minimum of 5 years.

Overview Of Literature: Several surgical options are available for the treatment of DLS, such as decompression only, decompression plus a short-segment fusion, or decompression with a long segment fusion.

Highly efficient and angle-tolerant mid-infrared filter based on a cascaded etalon resonator.

Mid-infrared of the 3 - 5 μm spectral region has attracted considerable attention in various fields. We report a highly efficient and angle-tolerant mid-infrared filter based on a cascaded etalon resonator. Two hybrid etalon resonators are serially stacked to make a single peak resonance with a well-suppressed sideband.