Optical pulse compression in 1.5 μm wavelength region usinglarge-positive-dispersion fibre and grating pair

Optical pulse compression at 1.5 μm has been conducted. 20 ps (FWHM) optical pulses from a Tl:KCl-colour-centre laser were compressed into pedestal-free 1.2 ps pulses using a large-positive-dispersion fibre and a grating pair. In addition, 280 fs pulses were obtained from the resultant 1.2 ps through the soliton compression effect in a negative-dispersion fibre     

Pentamer arrangements in fragments of human rotavirus inner capsids observed by low dose electron microscopy.

Fragments of disrupted capsids were frequently seen in purified preparations of human rotavirus inner capsids by negative staining method in electron microscopy. The ultrastructures of these fragments were analyzed in comparison with the T = 13L model. Well-resolved pentamers were rarely seen in the fragments on observation at the standard electron doses, but were frequently seen at low electron doses, which meant a better preservation of the steric structure of capsid fragments in the latter case. Thus advantages of low dose electron microscopy have been shown in observation of capsid fragments.     

High-?n, small-core single-mode fibres for efficient nonlinear optical effects

High-?n, small-core single-mode fibres have been fabricated with the VAD method. Results have been obtained for fibres having cores of ?n = 2.9% and diameter = 2.3 ?m and ?n = 1.9% and diameter = 2.8 ?m. Minimum losses for a ?n = 2.9% fibre and a ?n = 1.9% fibre are 0.82 dB/km at 1.61 ?m and 0.68 dB/km at 1.62 ?m. Other fundamental properties have been measured.     

Dimension-control technique in the VAD process and wholly synthesised single-mode fibre preform

A preform dimension control technique in the VAD process has been developed using chemical dry etching with fluoride gas applied to silica glass particles in an oxyhydrogen flame. Wholly synthesised VAD single-mode fibre preforms have been fabricated using this technique with high adjustment accuracy of outer/core diameter ratio. These preforms have exhibited excellent structural characteristics.     

Nanoscale modification of phase change materials with near-field light

Scanning near-field optical microscope (SNOM) was applied to the formation of ultrasmall phase change domains to investigate the feasibility of ultrahigh density data storage. Phase change domains ranging 60 – 100 nm in diameter, which is far beyond the diffraction limit, could be successfully written in amorphous GeSbTe recording film by point heating with pulsed laser light (λ=785 nm, 7 mW, 0.5 ms) through the optical fiber probe whose aperture size was nearly 50 – 100 nm. The detected power in observation of these recorded domains is 10² – 10³ times as high as that in magneto-optical observation. It indicates that phase change recording with SNOM has a potential to achieve ultrahigh density data storage (more than 100 Gb/in²) with high signal detection efficiency.     

Cranioplasty with neovascularized autogenous calvarial bone

We have presented two cases of cranioplasty with neovascularized autogenous calvarial bone. A surgical procedure applying the principle of flap prefabrication has been applied to the preservation of autogenous calvarial bone obtained during external cranial decompression. The rectus abdominis muscle flap was elevated. A subcutaneous pocket was prepared for preservation of calvarial bone integrated with the rectus abdominis muscle. The outer cortex of calvarial bone was removed partially by bone chiseling. The muscle flap was attached to the bone graft by means of two holes on the bone by suture. The calvarial bone, grafted onto the rectus abdominis muscle flap, was inserted into the subcutaneous pocket. Several weeks later, the neovascularized calvarial bone flap was dissected along with inferior epigastric pedicle. Cranioplasty was performed using the bone element of the flap. Revascularization was achieved by anastomosing the inferior epigastric vessels to the temporal vessels. The postoperative films demonstrated marked radiolucency at the borders of the flap, although bone scan documented that the flap was vascularized. We speculate that the transferred bony segment was not completely vascularized.     

High-birefringence polarizing fiber with flat cladding

This paper presents the theoretical and experimental investigations on polarization characteristics of PANDA fiber with flat cladding. It is theoretically shown that the modal birefringence in the flat-clad fiber is almost the same as that in the circular-clad fiber. The flat-clad PANDA fiber has been fabricated by grinding off the preform cladding on the opposite faces and then drawing with a low furnace temperature. The modal birefringence of the fiber isB = 5.9 times 10^{-4}and the separation of the bending loss edges for the two polarization modes isDeltaupsilon = 0.51in the normalized frequency. The polarizing region can be tuned from 1.3 to 1.56 μm by varying the fiber-bending diameter from 3.5 to 4.5 cm. A 1.5-m length of polarizing fiber exhibits extinction ratios of 44.9 and 44.4 dB with insertion losses for the guided mode of 0.25 and 0.41 dB at 1.3 and 1.56 μm, respectively.     

A body-mounted camera system for head-pose estimation and user-view image synthesis

In this paper, we propose a body-mounted system to capture user experience as audio/visual information. The proposed system consists of two cameras (head-detection and wide angle) and a microphone. The head-detection camera captures user head motions, while the wide angle color camera captures user frontal view images. An image region approximately corresponding to user view is then synthesized from the wide angle image based on estimated human head motions. The synthesized image and head-motion data are stored in a storage device with audio data. This system overcomes the disadvantages of head-mounted cameras in terms of ease of putting on/taking off the device. It also has less obtrusive visual impact on third persons. Using the proposed system, we can simultaneously record audio data, images in the user field of view, and head gestures (nodding, shaking, etc.) simultaneously. These data contain significant information for recording/analyzing human activities and can be used in wider application domains such as a digital diary or interaction analysis. Experimental results demonstrate the effectiveness of the proposed system.     

Fluorescent SiC and its application to white light-emitting diodes

Fluorescent-SiC (f-SiC), which contains donor and acceptor impurities with optimum concentrations, has high conversion efficiency from NUV to visible light caused by donor-acceptor-pair (DAP) recombination. This material can be used as a substrate for a near UV light-emitting diode (LED) stack, and leads to monolithic white LED device with suitable spectral property for general lighting applications. In this paper, we describe basic technologies of the white LED, such as optical properties of f-SiC substrate, and epitaxial growth of NUV stack on the f-SiC substrate.