 is calculated based on the measured refractive index of the GeGaS:Er glass to be 0.28 ± 0.02 dB/facet; this yields a calculated propagation loss of 1.6 ± 0.3 dB for the 4 mm sample. Figure 1 presents a schematic of the experimental setup used to characterize the waveguide performance.
After passive characterization, the morphology of the waveguides has been inspected using a white light transmission microscope. A micrograph of the waveguide with the lowest insertion loss is presented in Fig. 2(a). Material modification has been observed for pulse energies greater than 100 nJ and the waveguide morphology is typical of the thermal diffusion regime with limited heat accumulation [18]. This implies that using a higher repetition rate inscription laser may yield a more symmetric modified region and waveguide mode.
where Pout (pump) is the signal from the waveguide when the pump is present, fluorescence is the fluorescence emission due to the pump when no signal is present and Pout (no pump) is the signal from the waveguide when no pump is present.
Figure 3 shows the relative gain spectra of the Er doped GeGaS glass waveguide with a pump power of 500 mW. It can be seen that there is 1.0099 ± 0.0008 dB of gain at 1541 nm and 0.5435 ± 0.002 dB of gain at 1550 nm; this corresponds to a relative gain of 2.524 ± 0.002 dB/cm and 1.359 ± 0.005 dB/cm respectively. Although a relative gain 2.5 dB has been reported previously in chalcogenide glass waveguides which are fabricated in sputtered film and in erbium-ytterbium doped phosphate glass direct laser written waveguides [15,19], this is, to the best of the authors’ knowledge, the first demonstration of gain in a chalcogenide glass waveguide amplifier fabricated by DLW technology at telecommunications wavelengths. Importantly, due to the low phonon energy of the glass host, Er emissions at 2 μm, 2.75 μm, 3.6 μm and 4.5 μm should be accessible, making mid infrared amplifiers and sources at these interesting wavelengths realisable.
In comparison to other low phonon energy host media, including silicon and fluorozirconate based materials, the transmission range (up to 8 μm) and stability of GeGaS ChG offer significant advantages [20].
In this paper we detail the fabrication and characterization of a waveguide amplifier in Er-doped GeGaS glass by direct laser write technology. A significant relative gain of 1 dB or 2.5 dB/cm at 1541 nm is demonstrated for a device with an insertion loss of 2.58 dB. Further optimisation of the inscription parameters is expected to decrease propagation losses and in combination with longer waveguides, significant net gain can be achieved. Future work will be focused on establishing low loss guiding in the mid infrared spectral region allowing for the fabrication of waveguide amplifiers for the mid infrared spectral region.
We gratefully acknowledge the UKIERI programme for financial support to carry out this joint work. This work is funded by the UK Engineering and Physical Sciences Research Council (EPSRC) through grant EP/GO30227/1. S. Beecher acknowledges the funding from EPSRC. Thanks are due to Prof. C. K. Jayashankar, SV University, Tirupati for his technical support in synthesizing the optical quality glass and Dr. S. Ramgopal for designing the rocking furnace for making bulk homogeneous glasses. We also acknowledge many useful discussions with Dr. R. R. Thomson from Heriot-Watt University and Dr. N. D. Psaila from Optoscribe, Edinburgh.
About ten days ago I attended my friend’s wedding.
Here she is, the beautiful bride, arriving at the hotel.
I love to dance and don’t get that many opportunities so I really made the most of the evening. After several hours of non-stop dancing I was hot and sweaty, (as you are), and going out into the night air to go home I must have caught a chill which left me vulnerable to a ‘flu that was going around.
It started on the Sunday night with a hard cough, deep in the chest and I felt very tired and a bit spaced out. Fortunately I had some Thyme tincture to hand, that I had made during the summer and I started to take that straight away.
This tincture was made using Hungarian Poitin given to me by my friend Timea and it is very potent. If you have heard of Echinacea, a herb that many people take to fight off colds and ‘flus, Thyme is similarly anti-bacterial and anti-viral and works just as brilliantly to prevent infection. Despite a hard cough, this tincture helped me to expectorate and my chest did not get infected.
That could also have been thanks to the Dragon Fire Cider Vinegar I had made which is hot, hot, hot!!! VERY hot in fact but you feel great taking it. It is as if each mouthful swallowed dashes around your body straight to where it is needed most. This is such a simple remedy and it is advisable to always have some made up ready for the winter months. This is what is known as a folk remedy and many people have their own recipe. The recipe can be tweaked depending on what you have available in the kitchen cupboard. it is very simple to make, just marinade the ingredients in organic Apple Cider Vinegar for one month and then strain. It can be taken by the spoonful every day as a preventative or take several teaspoons if you are sick or even use as a condiment on your salad!
I used horseradish root, a large onion, several cloves of garlic, a big lump of ginger and a de-seeded chilli pepper. Just chop them up or grate them, put them in a Kilner jar or a jar with a non-metallic screw on lid and leave for one month. Then strain and enjoy.
Everyone knows that Chicken Soup is the best food whenever you are ill. It is not known exactly what it is about chicken soup that makes people feel better but it definitely nourishes the body when you don’t have much appetite. My husband made me a truly delicious soup that perked me up and put me on the road to wellness again.
We also took a good quality Omega 3 Oil to further prevent the virus from damaging our cells. So now, here we are, only ten days later, pretty much back to normal. Just in time to celebrate the Solstice!
For me, the Solstice is an important day to celebrate. The sun has stood in the sky for three days without change and then, like magic, the next day is a little bit longer. Suddenly the balance between dark and light is shifting more to the light and we will see the days becoming longer from now on. It is a time of hope and renewal and of looking forward to the spring. Many Solstice Blessings of Light and Love be upon you and yours.
If you would like to know how to make your own cold and ‘flu remedies to have close to hand, I am hosting a workshop on 21 January 2017.
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