Christian Vestergaard Poulsen

INCORPORATION OF N-3 POLYUNSATURATED FATTY ACIDS OF MARINE OR VEGETABLE ORIGIN INTO RAT ENTEROCYTE PHOSPHOLIPIDS

Abstract We examined time related effects of an intake of n-3 polyunsaturated fatty acids (PUFA) on the fatty acid profiles of rat enterocyte phospholipids. Three diets containing 20 wt% fat with similar levels of linoleic acid (C18:2n-6), approximately 11 wt% of the fatty acids, were prepared. The diets were: Palm oil diet (PD), 0.6 wt% n-3 PUFA; fish oil diet (FD), 32 wt% n-3 PUFA (C20-C22); and linseed oil diet (LD), 32 wt% n-3 PUFA (C18:3n-3). Forty weanling male Wistar rats were fed PD for 34 days and then divided into three groups. Two groups of sixteen rats each were then fed FD or LD, respectively, and eight rats remained on PD as a control group. At 6, 12, 18, 24, 72, 144, and 288 hours following the change of diets rats were killed, the enterocytes were isolated and the fatty acid profiles of the intestinal phospholipids were examined. During the first 12 hours following the change from PD to FD, the content of n-3 PUFA in the intestinal phospholipids increased from less than 1 mol% to approximately 20 mol%, whereas the contents of n-6 PUFA and of monoenes were reduced from 40 mol% to 28 mol% and from 19 mol% to 12 mol%, respectively. The fatty acid profiles were then largely constant during the remaining experimental period. In the LD group, the n-3 PUFA contents rose from less than 1 mol% to 10 mol% during the first 144 hours, and the content of n-6 PUFA and monounsaturated fatty acids were reduced from 40 mol% to 36 mol% and from 19 mol% to 14 mol%, respectively. Desaturation and elongation products of C18:3n-3, such as C20:5n-3, C22:5n-3 and C22:6n-3, were observed following intake of LD. All three groups contained approximately 40 mol% of saturated fatty acids in the intestinal phospholipids. Copyright

Novel type of highly photosensitive germanium-doped silica glass: codoping with nitrogen

A novel type of highly photosensitive germanosilicates has been developed. By adding ammonia to the gas mixture of silane, germane and nitrous oxide in the plasma enhanced chemical vapor deposition process, nitrogen has been incorporated in the glass matrix forming germania/silica oxynitrides. UV-induced refractive index increases greater than 3 multiplied by 10-3 has been measured without any hydrogen loading. Besides the highly increased photosensitivity the nitrogen doped germanosilicates exhibit excellent mechanical properties. Dependent on the deposition and annealing parameters the glass can be deposited to have zero stress when deposited on silicon. Further more can stable glasses with up to 30 mole % germania be deposited when nitrogen in incorporated.

UV-written Y-splitter in Ge-doped silica

A three-layer silica structure was grown on a 4-inch silicon wafer using plasma enhanced chemical vapor deposition. The 2.5 micrometers thick core layer is surrounded by 12 micrometers thick buffer and cladding layers. An aluminum layer, deposited on the cladding glass and patterned with the desired waveguide structures, serves as a mask for the UV exposure. An excimer laser operating on ArF giving an energy of 60 mJ/pulse was used to expose the sample to the total fluence of 4800 J/cm2 of 193 nm light. The rise in refractive index is estimated to be around 3 - 10-3 without hydrogen loading or any other kind of sensitization. The Y-splitters were evaluated on an automatic alignment setup using a semiconductor laser operating at 1542 nm. The splitting ratio was measured to be 1:1 at 1542 nm and 1:0.95 at 1310 nm. We measured the loss in the splitter to be 5 dB (fiber to fiberneglecting the splitting). The minimum coupling loss from fiber to waveguide was theoretically calculated to be 1.1 dB, leaving the propagation loss to be smaller than 2.8 dB/cm. The same value was measured for straight waveguides next to the couplers, indicating no measurable excess loss induced by the Y-splitters.

Applications of single frequency fiber lasers

In this paper we address fiber Bragg Grating (FBG) based fiber lasers, which consist of a rare earth single mode fiber with a FBG imposed in the fiber. The rare earth doped optical fiber is typically pumped with a semiconductor pump. These laser sources further exhibits extremely narrow spectral linewidth in the order of kHz and very low phase noise in the low frequency area making the single frequency fiber laser very attractive for many coherent applications such as interferometry, mid infrared generation, absolute reference sources, coherent communication, LIDAR and, due to the capability to be used in harsh environments, for down the well applications measuring pressure and temperature.

Ultra-strong UV written gratings in PECVD grown Ge doped silica waveguides with no hydrogen loading

In this paper we report what we believe to be the strongest waveguide gratings to date written by UV exposure of germanosilicate rib waveguides grown by PECVD, and without the use of hydrogen loading. Gratings of this strength should be more than adequate for fabricating WDM devices.

Supercontinuum laser sources future await wide applications

Recent advances in supercontinuum generation technology have enabled the development of lasers with higher power and broader spectral content, allowing exploitation of these light sources in a range of new and exciting application areas.

Ultra-Low Noise Fiber Lasers for Optical Fiber Sensor Systems

Fiber lasers provide a combination of low noise, potential for high power, small size, ease of use and high reliability, and as such present an attractive candidate for a number of fiber optic sensing applications.

Point-to-point UV-written planar waveguide components

Germanosilicate film waveguides have been fabricated by plasma enhanced chemical vapor deposition. In the film waveguides straight waveguides, directional couplers and a Y-splitter were written directly point to point with UV-light by focussing a 244 nm beam by a single lens. No kind of mask was used to define the structure. The propagation loss of a multi-mode UV-written waveguide has been measured to 0.3 dB/cm, which is excellent for directly written waveguides. The UV-induced change of refractive index in the written components is estimated to be between 4 (DOT) 10-3 and 6 (DOT) 10-3. This provides a highly flexible and fast method for fabrication of new waveguide components.