Jun-kyo Lee

ASE-injected wideband gain lasers covering C-band channels with temperature range from - 30 to 80/spl deg/C in a 155 Mb/s WDM-PON

We report a spectrum-sliced amplified spontaneous emission (ASE)-injected wideband gain laser covering entire C-hand wavelength channels with temperature range from -30 to 80 /spl deg/C in 155 Mb/s upstream transmissions over 25 km of single mode fiber in a wavelength division multiplexed-passive optical networks (WDM-PON).

Active contour configuration model in estimating the posterior ablative margin on image fusion of real-time ultrasound and 3D ultrasound or magnetic resonance images for radiofrequency ablation: an experimental study

Purpose The purpose of this study was to evaluate the accuracy of an active contour model for estimating the posterior ablative margin in images obtained by the fusion of real-time ultrasonography (US) and 3-dimensional (3D) US or magnetic resonance (MR) images of an experimental tumor model for radiofrequency ablation. Methods Chickpeas (n=12) and bovine rump meat (n=12) were used as an experimental tumor model. Grayscale 3D US and T1-weighted MR images were pre-acquired for use as reference datasets. US and MR/3D US fusion was performed for one group (n=4), and US and 3D US fusion only (n=8) was performed for the other group. Half of the models in each group were completely ablated, while the other half were incompletely ablated. Hyperechoic ablation areas were extracted using an active contour model from real-time US images, and the posterior margin of the ablation zone was estimated from the anterior margin. After the experiments, the ablated pieces of bovine rump meat were cut along the electrode path and the cut planes were photographed. The US images with the estimated posterior margin were compared with the photographs and post-ablation MR images. The extracted contours of the ablation zones from 12 US fusion videos and post-ablation MR images were also matched. Results In the four models fused under real-time US with MR/3D US, compression from the transducer and the insertion of an electrode resulted in misregistration between the real-time US and MR images, making the estimation of the ablation zones less accurate than was achieved through fusion between real-time US and 3D US. Eight of the 12 post-ablation 3D US images were graded as good when compared with the sectioned specimens, and 10 of the 12 were graded as good in a comparison with nicotinamide adenine dinucleotide staining and histopathologic results. Conclusion Estimating the posterior ablative margin using an active contour model is a feasible way of predicting the ablation area, and US/3D US fusion was more accurate than US/MR fusion.

S-band wideband gain lasers with 32 channel coverage and launching power 2dBm for WDM-PON

Uncooled ASE-injected WBG-LDs in the S-band are first developed as downstream sources in WDM-PONs. The single WBG-LD covers 100 GHz-spaced 32 channels and allows BERs of 10-10 with +2 dBm launching power over 25 km

Selective area growth of AlGaInAs for spot-size converter integrated laser diode

AlGaInAs selective area growth on a masked InP substrate has been investigated to develop a spot-size converter integrated laser diode. After migration blocking area was applied to suppress surface migration effect, selective grown AlGaInAs layer shows improved characteristics in PL measurement. The threshold current was 25 mA and 62 mA at 25 /spl deg/C and 85 /spl deg/C, respectively. The FWHMs (full width at half maximum) of horizontal and vertical far field pattern were reduced from 25/spl deg/; and 42/spl deg/ into 22/spl deg/ and 30/spl deg/, respectively.