Jung Bum Lee

Silicon-Based 2-D Slab Photonic Crystal TM Polarizer at Telecommunication Wavelength

We report an extremely compact (15.4 mum x 8 mum) silicon-based 2D slab nano photonic crystal (PC) transverse-magnetic (TM) polarizer which blocks propagation of the transverse-electric (TE) polarized light but passes TM polarized light around telecommunication wavelength (1550 nm). The TE polarized light totally vanishes but the TM polarized light propagates with some attenuation in a length of mere 4.9 mum and it has a great potential to be integrated in a complex photonic integrated circuits. To our knowledge, this is the first experimental demonstration of a silicon-based PC TM polarizer at 1.55-mum wavelength. The plane wave expansion method (PWEM) and 2-D and 3-D finite-difference time-domain (FDTD) simulation were utilized to design a periodic triangular array of air holes in 340-nm-thick silicon with a diameter of 170 nm and pitch distance of 347 nm for the TM polarizer and 371 nm for the input and output waveguide. Such a PC TM polarizer was fabricated in silicon-on-insulator wafer using focused ion beam and reactive ion etching. The device was characterized using tunable lasers in the wavelength range of 1528 nm~1604 nm. Transmitted light intensities of the TE and TM polarized lights were measured which clearly showed the TE polarized light is filtered out around 1.55-mum wavelength.

Evaluation of Associated Carpal Bone Fractures in Distal Radial Fractures

Background The purpose of this study was to investigate the frequency and distribution of associated carpal bone fractures (CBFs) in distal radial fractures (DRFs). Methods Three hundred and thirteen patients who underwent surgical treatment for DRFs between March 2007 and January 2010 were reviewed retrospectively. In this study, 223 patients who had preoperative computed tomography (CT) were included. We investigated the frequency and distribution of associated CBFs on CT scans. The relationship between the frequency of associated CBFs and patient factors such as age, gender, body mass index, and the mechanism of injury was assessed. Results CBFs were complicated in 46 of 223 DRFs (20.9%). The distribution of CBFs was 23 cases in the triquetrum, 16 in the lunate, 12 in the scaphoid, five in the hamate, and four in the pisiform. Among the 46 cases, a fracture of one carpal bone occurred in 36 cases, two in seven cases, three in two cases, and four in one case. In 10 of the 46 cases, associated CBFs occurred in more than two carpal bones. No significant differences were observed for age, sex, body mass index, or the mechanism of injury between patients with DRFs and CBFs and those without CBFs. Conclusions Because CBFs that mainly occur in the proximal carpal row are complicated in DRFs at a relatively high frequency, assessment of carpal bones using CT scans is beneficial.

Unstable Simple Elbow Dislocation Treated with the Repair of Lateral Collateral Ligament Complex

Background Unstable simple elbow dislocation (USED) repair is challenged by the maintenance of joint reduction; hence, primary repair or reconstruction of disrupted ligaments is required to maintain the congruency and allow early motion of the elbow. We evaluated the effectiveness and the outcome of lateral collateral ligament (LCL) complex repair with additional medial collateral ligament (MCL) repair in cases of USED. Methods We retrospectively reviewed 21 cases of diagnosed USED without fractures around the elbow that were treated with primary ligament repair. In all cases, anatomical repair of LCL complex with or without common extensor origin was performed using suture anchor and the bone tunnel method. Next, the instability and congruency of elbow for a full range of motion were evaluated under the image intensifier. MCL was repaired only if unstable or incongruent elbow was observed. Clinical outcomes were evaluated using the Mayo elbow performance score (MEPS) and radiographic outcomes on last follow-up images. Results All cases achieved a stable elbow on radiographic and clinical results. LCL complex repair alone was sufficient to obtain the stable elbow in 17 of 21 cases. Four cases required additional MCL repair after restoration of the LCL complex. The overall mean MEPS was 91 (range, 70 to 100): excellent in 12 cases, good in 7 cases, and fair in 2 cases. All 17 cases with LCL complex repair only and 2 of 4 cases with additional MCL repair had excellent or good results by MEPS. Conclusions USED requires surgical treatment to achieve a congruent and stable joint. If the repair of lateral stabilizer such as LCL complex acquires enough joint stability to maintain a full range of motion, it may not be necessary to repair the medial stabilizer in all cases of USED.

Shaft Fractures of Both Forearm Bones: The Outcomes of Surgical Treatment with Plating Only and Combined Plating and Intramedullary Nailing.

Background Plate fixation is the most commonly used technique for the treatment of shaft fractures of both forearm bones (SFBFBs). However, all fractures are difficult to treat with plate fixation because of soft tissue injuries, fracture patterns, or the patients condition. The purpose of this study is to compare the functional results of plate fixation only and combined plate and intramedullary (IM) nail fixation in SFBFBs. Methods Fifty-nine cases of SFBFBs that were surgically treated from June 2007 to July 2012 were retrospectively reviewed. In this study, 47 cases that were followed up for more than 12 months were included. All SFBFBs were divided into two groups according to the methods used for internal fixation: plate fixation only (group A) and combined plate and IM nail fixation (group B). The fixation methods were determined intraoperatively. Plate fixation was considered as the first option in all cases, but combined plate and IM nail fixation was selected as the second option if it was difficult to be fixed with plate only. Groups A and B comprised of 31 and 16 cases, respectively. The functional results were evaluated by the Grace and Eversmann rating system and the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire. Results In groups A and B, a radiologic union was achieved in 30/31 and 14/16 cases and average union time was 11.1 and 17.8 weeks, respectively. According to the Grace and Eversmann rating system, group A had excellent results in 15 cases, good in 14, acceptable in one, and unacceptable in one. Group B had excellent results in three cases, good in nine, acceptable in two, and unacceptable in two. The average DASH score was 7.1 points (range, 0 to 19.2 points) in group A and 15.1 points (range, 0 to 29.6 points) in group B. Three cases of nonunion with unacceptable results achieved a bony union by additional procedures and the functional results of these cases improved to good or excellent. Conclusions The functional results and the average union time were superior in group A than in group B. However, we think that combined fixation is a useful method for SFBFBs that cannot be treated with plate fixation only.

Corrections to “Silicon-Based 2-D Slab Photonic Crystal TM Polarizer at Telecommunication Wavelength” [15 Apr 08 641-643]

We report an extremely compact (15.4 mum x 8 mum) silicon-based 2D slab nano photonic crystal (PC) transverse-magnetic (TM) polarizer which blocks propagation of the transverse-electric (TE) polarized light but passes TM polarized light around telecommunication wavelength (1550 nm). The TE polarized light totally vanishes but the TM polarized light propagates with some attenuation in a length of mere 4.9 mum and it has a great potential to be integrated in a complex photonic integrated circuits. To our knowledge, this is the first experimental demonstration of a silicon-based PC TM polarizer at 1.55-mum wavelength. The plane wave expansion method (PWEM) and 2-D and 3-D finite-difference time-domain (FDTD) simulation were utilized to design a periodic triangular array of air holes in 340-nm-thick silicon with a diameter of 170 nm and pitch distance of 347 nm for the TM polarizer and 371 nm for the input and output waveguide. Such a PC TM polarizer was fabricated in silicon-on-insulator wafer using focused ion beam and reactive ion etching. The device was characterized using tunable lasers in the wavelength range of 1528 nm~1604 nm. Transmitted light intensities of the TE and TM polarized lights were measured which clearly showed the TE polarized light is filtered out around 1.55-mum wavelength.

Silicon-Based 2D Slab Nano Photonic Crystal Thermo-Optic Light Modulator

We report a compact (20.9 mum x 20 mum) silicon-based 2D slab nano photonic crystal light modulator tuned by the thermo-optic modulation of the cut-off wavelength about 1,470 nm. Plane wave expansion method (PWEM) and 2D finite difference time domain (FDTD) method were utilized to design a triangular lattice line defect photonic crystal waveguide in 220 nm thick silicon with diameter of 270 nm and pitch distance of 400 nm. Micro heater was situated right next to the line defect photonic crystal to provide localized resistive heating. The device was characterized in the wavelength range of 1,400 nm~1,520 nm. Waveguide mode, cut off mode and photonic crystal mode were found which clearly shows cut-off about 1,470 nm wavelength.

Negative Refraction in Si-Based 2-D Photonic Crystal Structures

Si-based 2-dimensional slab photonic crystal structures were designed and fabricated for operation in the near-infrared region. Negative refraction was experimentally observed in the integrated device structures including in- and out-coupling waveguides.