948 research outputs found
Multi-wavelength fiber laser with erbium doped zirconia fiber and semiconductor optical amplifier
No full textMulti-wavelength hybrid fiber lasers are demonstrated in both ring and linear cavities using a fabricated Erbium-doped Zirconia fiber (EDZF) and semiconductor optical amplifier (SOA) as gain media. In both configurations, the a fiber loop mirror, which is constructed using a 3 m long polarization maintaining fiber (PMF) and a polarization insensitive 3dB coupler is used as a comb filter for the fiber laser. In the ring cavity, 10 simultaneous lines with peak power above -26 dBm is obtained at 1550 nm region. This is an improvement compared to the linear cavity configuration which has only 5 simultaneous lines observed from wavelength 1556.1 nm to 1563.0 nm with the peak power above -40 dBm. Both hybrid lasers has a constant line spacing of 1.7 nm, which is suitable for wavelength division multiplexing and sensing applications and shows a stable operation at room temperature
Single mode erbium ytterbium-doped fiber laser with multimode pumping
No full textAn efficient and stable laser action from a double-clad erbium/ytterbium-doped fiber (EYDF) is demonstrated using a fiber Bragg grating at room temperature. The fiber laser operates at wavelength of 1552.3 nm with a slope efficiency of 38% when pumped by multi-mode 915 nm laser diodes. However, the slope efficiency is higher in the EYDF laser configured with double-sided output due to the high splicing loss between the multi-mode combiner and double-clad EYDF. The laser also has a spectral bandwidth of 0.2 nm and signal to noise ratio of more than 25 dB. The threshold power to achieve lasing is measured to be approximately 500 mW for this laser
Improving the performance of the trolley supply chain with a focus on visibility.
No full textThe lack of visibility, significant investment and a presumption of fleet shrinkage falter the decision-making process of a Dutch airline. Five decision areas have been identified and for each decision area improvements strategies or alternatives have been designed. Selecting the best alternative per decision area is a multi-criteria decision making problem. Therefore, a more sophisticated method is required to support the decision-maker. For this problem the novel Best-Worst Multi-Criteria Decision Making Method (BWM) has been selected. The BWM has been successfully applied to select the best alternative per decision area. Next steps for the airline are the implementation of the chosen alternatives.SEPAMTransport & LogisticsTechnology, Policy and Managemen
Distributed feedback Er-Yb co-doped phosphate fibre laser
No full textA distributed feedback fibre laser made of highly Er-Yb co-doped phosphate glass fibre was demonstrated experimentally. The 45 mm long fibre laser device operated at 1540 nm with more than 50 dB side mode suppression ratio. However, the output power was still relatively lower due to un-optimized grating structure and thermal management
An erbium/ytterbium co-doped fibre amplifier using 1058 nm pumping
No full textThis paper demonstrates an erbium/ytterbium co-doped fi bre amplifi er (EYDFA) which used a pumping wavelength of 1058 nm, whereby the amplifi cation was assisted by the energy transfer between Yb and Er ions. The energy transfer increased the erbium doping concentration limit that was imposed by concentration quenching in erbium-doped fi bre. The optimum length was obtained at 4m~6m for erbium/ytterbium co-doped fi bre with Er ion concentration of 1000 p.p.m. This enabled the development of a compact amplifi er with a shorter gain medium compared to erbium-doped fi bre amplifi ers which use a gain medium of up to 15 m. A 1058 nm pumping wave-length was used for the EYDFA, as 1480 nm pumping resulted in severely degraded gain and noise fi gures because the energy transfer could not be achieved. The use of the optical isolator improved the small signal gain and noise fi gure by about 4.8 dB and 1.6 dB, respectively. Without the isolator, gain saturation and a noise fi gure penalty were observed due to the oscillating laser which was created at around 1534 nm by spurious refl ection. This showed that the usage of optical isolators was an important aspect to consider when designing an EYDFA
SOA-based multi-wavelength source
No full textWe demonstrate a multi-wavelength light source using a semiconductor optical amplifier (SOA) in conjunction with an array waveguide grating (AWG). The experimental results showed more than 20 channels with a wavelength separation of 0.8 nm and an optical signal-to-noise ratio of more than 10 dB under room temperature. The channels operated at the wavelength region from 1530.4 nm to 1548.6 nm, which corresponded to AWG filtering wavelengths with SOA drive current of 350 mA. The proposed light source had the advantages of a simple and compact structure, multi-wavelength operation and the system could be upgraded to generate more wavelengths
Graphene oxide-polyethylene oxide (PEO) film as saturable absorber on mode-locked erbium doped fiber laser generation
No full textMode-locked erbium doped fiber laser by using graphene oxide (GO) that obtained by oxidation and ultra-sonification process of natural graphite was reported. GO produced was dissolved in water and mixed with Polyethylene Oxide (PEO) to form film. When the fabricated GO-PEO film saturable was employed in the proposed EDFL configuration, the laser generates 1.25 ps pulses at a repetition rate of 21.8 MHz with pump input of 70 mW. The stable mode-locking operation was observed within pump input power of 70 mW until 175 mW. Soliton-like spectrum was achieved with prominent Kelly-sideband and centre wavelength of 1558.6 nm
Buckfast Abbey Archaeological Projects 1982-2016 Photographic Archive
No full textThis photographic archive is intended to augment the two publications on the abbey's archaeology by S.W. Brown (Proceedings of the Devon Archaeological Society 46, 1988, 13-89; and Devon Archaeological Society Occasional Paper 21, 2018) and the series of more detailed interim archive reports appearing on the ADS website (unpublished grey literature, accessible via author Stewart Brown)
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