WDM signal regeneration using a single all-optical device

Using the principle of quasi-continuous filtering in a non-linear fibre, we propose an optical device for the simultaneous regeneration of sevaral channels at 40 Gbit/s. Simulations predict an improvement of the signal quality for four channels by more than 6.8 dB.

WDM signal regeneration using a single all-optical device

Using the principle of quasi-continuous filtering in a non-linear fibre, we propose an optical device for the simultaneous regeneration of sevaral channels at 40 Gbit/s. Simulations predict an improvement of the signal quality for four channels by more than 6.8 dB.

Tipificação citológica do líquido amniótico no momento do parto de bezerros Nelore oriundos de produção In Vitro, transferência de embrião e inseminação artificial

Pós-graduação em Medicina Veterinária - FMVZ

OTDM network processing using all-optical and electro-optical devices

The current optical communications network consists of point-to-point optical transmission paths interconnected with relatively low-speed electronic switching and routing devices. As the demand for capacity increases, then higher speed electronic devices will become necessary. It is however hard to realise electronic chip-sets above 10 Gbit/s, and therefore to increase the achievable performance of the network, electro-optic and all-optic switching and routing architectures are being investigated. This thesis aims to provide a detailed experimental analysis of high-speed optical processing within an optical time division multiplexed (OTDM) network node. This includes the functions of demultiplexing, 'drop and insert' multiplexing, data regeneration, and clock recovery. It examines the possibilities of combining these tasks using a single device. Two optical switching technologies are explored. The first is an all-optical device known as 'semiconductor optical amplifier-based nonlinear optical loop mirror' (SOA-NOLM). Switching is achieved by using an intense 'control' pulse to induce a phase shift in a low-intensity signal propagating through an interferometer. Simultaneous demultiplexing, data regeneration and clock recovery are demonstrated for the first time using a single SOA-NOLM. The second device is an electroabsorption (EA) modulator, which until this thesis had been used in a uni-directional configuration to achieve picosecond pulse generation, data encoding, demultiplexing, and 'drop and insert' multiplexing. This thesis presents results on the use of an EA modulator in a novel bi-directional configuration. Two independent channels are demultiplexed from a high-speed OTDM data stream using a single device. Simultaneous demultiplexing with stable, ultra-low jitter clock recovery is demonstrated, and then used in a self-contained 40 Gbit/s 'drop and insert' node. Finally, a 10 GHz source is analysed that exploits the EA modulator bi-directionality to increase the pulse extinction ratio to a level where it could be used in an 80 Gbit/s OTDM network.

Direct comparison of the gravimetric responsivities of ZnO-based FBARs and SMRs

Film bulk acoustic resonators (FBARs) and solidly mounted resonators (SMRs) have the potential to significantly improve upon the sensitivity and minimum detection limit of traditional gravimetric sensors based on quartz crystal microbalances (QCMs) and surface acoustic wave resonators (SAWs). To date, neither FBAR nor SMR devices have been demonstrated to be superior to the other; hence the choice between them depends primarily on the users' ability to design/fabricate membranes and/or Bragg reflectors. In this work, it is shown that identically designed FBAR and SMR devices resonating at the same frequency exhibit different responsivities to mass loadings, Rm, and that the SMRs are less responsive than the FBARs. For the specific device design and resonant frequency (~2 GHz) of the resonators presented here, the FBARs' mass responsivity is ~20% greater than that of the SMRs', and although this value is not universal for all possible device designs, it clearly shows that FBAR devices should be favoured over SMRs in gravimetric sensing applications where the FBARs' fragility is not an issue. Numerical calculations based on Mason's model offer an insight into the physical mechanisms behind the greater FBARs responsivity, and it was shown that the Bragg reflector has an effect on the acoustic load at one of the facets of the piezoelectric films which is in turn responsible for the SMRs' lower responsivity to mass loadings. © 2013 Elsevier B.V.

Experimental comparison of FBARs and SMRs responsitivities to mass loadings

The utilisation of thin film technology to develop film bulk acoustic resonators (FBARs) and solidly mounted resonators (SMRs), offers great potential to outperform the sensitivity and minimum detection limit of gravimetric sensors. Up to now, the choice between FBARs and SMRs depends primarily on the users' ability to design and fabricate Bragg reflectors and/or membranes, because neither of these two types of resonators has been demonstrated to be superior to the other. In the work reported here, it is shown that identically designed FBARs and SMRs resonating at the same frequency exhibit different responsitivities, Rm, to mass loadings, being the FBARs more responsive than the SMRs. For the specific device design and resonant frequency (∼2 GHz) of the resonators presented, FBARs' mass responsitivity is ∼20% greater than that of SMRs, and although this value should not be taken as universal for all possible device designs, it clearly indicates that FBAR devices should be favoured over SMRs in gravimetric sensing applications. © 2012 IEEE.

Polymer light emitting devices with Langmuir-Blodgett (LB) films: Enhanced performance due to an electron-injecting layer of ionomers

Polymer light-emitting devices (PLEDs) have been produced with Langmuir-Blodgett (LB) films from poly(2-methoxy-5-hexyloxy)-p-phenylenevinylene (OC1OC6-PPV) as the emissive layer and an ionomer of a copolymer of styrene and methylmethacrylate (PS/PMMA) as an electron-injection layer. The main features of such devices are the low operating voltages, obtainable firstly due to the good quality of the ultrathin LB films that allows PLEDs to be produced reproducibly and secondly due to the improved electrical and luminance properties brought by the electron-injection layer. Also demonstrated is the superior performance of an all-LB device compared to another one produced with cast films of the same materials. Published by Elsevier B.V.

Fixed-time artificial insemination with estradiol and progesterone for Bos indicus cows I: Basis for development of protocols

Five experiments were conducted on commercial farms in Brazil aiming to develop a fixed-time artificial insemination (TAI) protocol that achieved pregnancy rates between 40% and 55% in Bos indicus cows. These studies resulted in the development of the following protocol: insertion of all intravaginal device containing 1.9 g of progesterone (CIDR) plus 2.0 mg im estradiol benzoate on Day 0; 12.5 mg im dinoprost tromethamine on Day 7 in cycling cows or oil Day 9 in anestrous cows; CIDR withdrawal plus 0.5 mg im estradiol cypionate plus temporary calf removal on Day 9; TAI (48 h after CIDR withdrawal) plus reuniting of calves with their dams on Day 11. Reduced dose of prostaglandin F(2 alpha) (PGF(2 alpha): 12.5 mg im dinoprost tromethamine) effectively caused luteolysis. In cycling cows, fertility was greater when the treatment with PGF(2 alpha) was administered on Day 7 than oil Day 9, but in anestrous cows, no effects of time of the PGF(2 alpha) treatment were found. Estradiol cypionate effectively replaced estradiol benzoate or gonadotropin-releasing hormone as the ovulatory stimulus, reducing labor and cost. In this protocol, CIDR inserts were successfully used four times (9 d each use) with no detrimental effects on fertility. (C) 2009 Elsevier B.V. All rights reserved.

Desenvolvimento de um paralelizador intra-oral e verificação de sua precisão como método de transferência de planos de guia: Estudo laboratorial

Pós-graduação em Odontologia Restauradora - ICT

Postectomia com dispositivo plástico versus postectomia convencional para circuncisão em crianças: revisão sistemática e metanálise

Pós-graduação em Bases Gerais da Cirurgia - FMB