Characterising neovascularisation in fracture healing with laser Doppler and micro-CT scanning

Vascularity of the soft tissues around a bone fracture is critical for successful healing, particularly when the vessels in the medullary canal are ruptured. The objective of this work was to use laser Doppler and micro-computer tomography (micro-CT) scanning to characterise neovascularisation of the soft tissues surrounding the fracture during healing. Thirty-two Sprague–Dawley rats underwent mid-shaft osteotomy of the left femur, stabilised with a custom-designed external fixator. Five animals were killed at each of 2, 4 days, 1, 2, 4 and 6 weeks post-operatively. Femoral blood perfusion in the fractured and intact contralateral limbs was measured using laser Doppler scanning pre- and post-operatively and throughout the healing period. At sacrifice, the common iliac artery was cannulated and infused with silicone contrast agent. Micro-CT scans of the femur and adjacent soft tissues revealed vessel characteristics and distribution in relation to the fracture zone. Blood perfusion dropped immediately after surgery and then recovered to greater than the pre-operative level by proliferation of small vessels around the fracture zone. Multi-modal imaging allowed both longitudinal functional and detailed structural analysis of the neovascularisation process

All-solution doping technique for high power fiber lasers - refractive index influence in the vicinity of Al:P = 1:1

A novel and simple solution doping technique is used to explore the refractive index behavior of Al,P-doped SiO2 in the vicinity of the Al:P-ratio of 1:1 at low doping concentrations. It is found that even if Al:P = 1:1 is matched precisely an index increase is observed. This is in contradiction to previous findings in the literature and the already sophisticated models need to be refined in this region

Coherently combined 16-channel multicore fiber laser system

We present a coherently combined laser amplifier with 16 channels from a multicore fiber in a proof-of-principle demonstration. Filled-aperture beam splitting and combination, together with temporal phasing, is realized in a compact and low-component-count setup. Combined average power of up to 70 W with 40 ps pulses is achieved with combination efficiencies around 80%

Modelling the refractive index behavior of Al,P-doped SiO2, fabricated by means of all-solution doping, in the vicinity of Al:P = 1:1

A novel and simple solution doping technique is used to explore the refractive index behavior of Al,P-doped SiO2 in the vicinity of the Al:P-ratio of 1:1 at low doping concentrations (0.4 up to 2.0 mol% Al2O3 and/or P2O5). It is found that even if Al:P = 1:1 is matched precisely, an index increase is observed. This is in contradiction to previous findings in the literature and the already sophisticated models need to be refined in this region. In the proposed model, an incomplete formation of AlPO4 is assumed and solves the contradiction. Furthermore, the presented model can be combined with previous literature models

MCVD based fabrication of low-NA fibers for high power fiber laser application

The fabrication of Yb doped fibers with low-NA (0.04) for high-power fiber laser applications in the multi-kW class is presented and discussed. Laser tests with ~3 kW output power and excellent beam quality are demonstrated

kW-class fiber laser prepared using an alternative solution doping MCVD-technique

Summary form only given. The growing demand for high power fiber lasers and the need for higher and higher cw-output powers pose new challenges to fiber technologists. The fabrication of suitable low-NA fibers in the materials system of choice, Yb, Al, P-doped silica, is challenging. Hence, new, facilitating fabrication methods are required. In this contribution we report on fabrication principles of a promising alternative solution doping method - the so called all-solution doping method [1].The presented all-solution doping method is used produce step index low-NA fibers as well as specialty index profile fibers. Here a porous, undoped SiO2 layer is deposited on the inside of a substrate tube and subsequently impregnated using a solution containing aluminum, phosphorus and ytterbium. The respective ratios of the dopants can already be predetermined in the solution. Thus the ratios of the respective dopants can be adjusted straightforwardly as opposed to the state-of-the-art method. Preforms prepared with this method were drawn to fibers (22/450) and used within a MOPA setup

All-solution doping technique for tailoring core composition toward Yb:AlPO4:SiO2

A modified solution doping approach for incorporating appropriate amounts of Yb, Al and P in fused silica is shown. The mitigation of phosphorus evaporation is intended by the initial formation of AlPO4 from solution

TMI investigations of very low NA Yb-doped fibers and scaling to extreme stable 4.4 kW single-mode output

We present our recent results of scaling low-NA fibers to high average power by overcoming the TMI-limitations. We obtained a record output power of 4.4kW with a higher stability and smaller bending compared to our previous result