Analysis of a distributed fiber-optic temperature sensor using single-photon detectors

We demonstrate a high-accuracy distributed fiber-optic temperature sensor using superconducting nanowire single-photon detectors and single-photon counting techniques. Our demonstration uses inexpensive single-mode fiber at standard telecommunications wavelengths as the sensing fiber, which enables extremely low-loss experiments and compatibility with existing fiber networks. We show that the uncertainty of the temperature measurement decreases with longer integration periods, but is ultimately limited by the calibration uncertainty. Temperature uncertainty on the order of 3 K is possible with spatial resolution of the order of 1 cm and integration period as small as 60 seconds. Also, we show that the measurement is subject to systematic uncertainties, such as polarization fading, which can be reduced with a polarization diversity receiver

Design and simulation of 1.28 Tbps dense wavelength division multiplex system suitable for long haul backbone

Wavelength division multiplex (WDM) system with on / off keying (OOK) modulation and direct detection (DD) is generally simple to implement, less expensive and energy efficient. The determination of the possible design capacity limit, in terms of the bit rate-distance product in WDM-OOK-DD systems is therefore crucial, considering transmitter / receiver simplicity, as well as energy and cost efficiency. A 32-channel wavelength division multiplex system is designed and simulated over 1000 km fiber length using Optsim commercial simulation software. The standard channel spacing of 0.4 nm was used in the C-band range from 1.5436-1.556 nm. Each channel used the simple non return to zero - on / off keying (NRZ-OOK) modulation format to modulate a continuous wave (CW) laser source at 40 Gbps using an external modulator, while the receiver uses a DD scheme. It is proposed that the design will be suitable for long haul mobile backbone in a national network, since up to 1.28 Tbps data rates can be transmitted over 1000 km. A bit rate-length product of 1.28 Pbps.km was obtained as the optimum capacity limit in 32 channel dispersion managed WDM-OOK-DD system.Comment: Accepted for publication in Journal of Optical Communications - De Gruyte

Feasibility of quantum key distribution through dense wavelength division multiplexing network

In this paper, we study the feasibility of conducting quantum key distribution (QKD) together with classical communication through the same optical fiber by employing dense-wavelength-division-multiplexing (DWDM) technology at telecom wavelength. The impact of the classical channels to the quantum channel has been investigated for both QKD based on single photon detection and QKD based on homodyne detection. Our studies show that the latter can tolerate a much higher level of contamination from the classical channels than the former. This is because the local oscillator used in the homodyne detector acts as a "mode selector" which can suppress noise photons effectively. We have performed simulations based on both the decoy BB84 QKD protocol and the Gaussian modulated coherent state (GMCS) QKD protocol. While the former cannot tolerate even one classical channel (with a power of 0dBm), the latter can be multiplexed with 38 classical channels (0dBm power each channel) and still has a secure distance around 10km. Preliminary experiment has been conducted based on a 100MHz bandwidth homodyne detector.Comment: 18 pages, 5 figure

Sustainable economic development : concept, principles and management from Islamic perspective

The basic concern of development in Islamic economic system is on human welfare. This is in line with the very basic objective of Islamic jurisprudence (Shari’ah ) which puts important to the welfare of the people and their relief from hardship. Economic development should be consistent with this central objective of shari`ah. The center for development process in Islam relies on man as an economic agent. It is man to be educated on the entire development process by integrating sosial development, economic development and environmental conservation and protection. This paper attempts to explain the concept, principles and management of sustainable economic development from Islamic perspective. The paper would start by defining the concept of sustainable economic development and development goals. Next, the Islamic principles for sustainable economic development would be discussed, followed by the discussion on the management of sustainable economic development from Islamic perspective. In conclusion, the paper strongly suggests the economic development process to fully adhere to the Islamic principles as the key for sustainable development which covers both the material and non-material aspects of life. Keywords: Sustainable development, Economic development, management, Islamic economics, economic syste

Processo de calibração em campo de amplificadores Raman distribuídos contra-propagantes para aprimoramento do controle automático de ganho

Orientador: Max Henrique Machado CostaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: Os amplificadores Raman distribuídos (DRAs) têm se mostrado interessantes nas redes ópticas elásticas porque eles permitem, em algumas configurações, aumentar a banda de amplificação, melhorar a planicidade dos canais e diminuir a inserção de ruído em relação aos amplificadores a fibra dopada com érbio (EDFAs) convencionais. No entanto, existem problemas operacionais nos DRAs pois a amplificação acontece na própia fibra de transmissão. As características desta fibra, que não são sempre perfeitamente conhecidas nas instalações em campo, têm uma influência sobre o ganho Raman utilizado para a amplificação do sinal. Como consequência, os lasers de bombeio dos DRAs devem ser ajustados para se adaptar as propriedades da fibra de maneira a providenciar um controle de ganho automático preciso. Esta dissertação de Mestrado apresenta um método de calibração em campo dos amplificadores Raman distribuídos contra-propagantes para melhorar a precisão do controle automático de ganho. A eficiência deste método é demonstrada em simulação para fibras de transmissão tendo diferentes perfis de atenuação e é validada experimentalmente com fibras tendo diferentes perfis de atenuação e com emendas localizadas a várias distâncias dos lasers de bombeio dos DRAs. Enfim, o impacto do método de calibração na planicidade do ganho e na figura de ruído do amplificador é apresentado em simulaçãoAbstract: Distributed Raman amplifiers (DRAs) have gained interest for elastic optical networking (EON) because they allow, in some configurations, to increase the amplification bandwidth, to enhance the gain flatness and to decrease the noise insertion compared to conventional erbium doped fiber amplifiers (EDFAs). However, there are operational issues in the deployment of DRAs because the transmission fiber itself serves as the gain medium. The characteristics of this fiber, that are not always perfectly known in field installations, have an influence on the Raman gain used for the signal amplification. As a consequence, the pump power of the DRAs must be adjusted to adapt to the actual fiber properties to provide accurate automatic gain control. This Masters dissertation presents a field calibration procedure for distributed counter-propagating Raman amplifiers to enhance their automatic gain control. The performance of this calibration procedure is demonstrated in simulations for transmission fibers of different attenuation profiles and is validated experimentally with fibers of different attenuation profiles and with splices located at several distances from the DRAs' pump lasers. Finally, the impact of this calibration procedure on the amplifiers gain flatness and noise figure is presented in simulationsMestradoTelecomunicações e TelemáticaMestre em Engenharia Elétric

Fiber laser systems shine brightly

Describes the advancements in active fiber laser systems. Outline of cladding pumping technique for enhanced power scaling; Improved energies and peak powers; Extended wavelength range; Frequency doubling with fiber sources

Characterization Of Dicrete Gain Clamped Raman Fiber Amplifier

Modern Dense Wavelength Division Multiplexing (DWDM) optical networks consist of add/drop elements to enhance the flexibility of the network. However it introduces transient phenomena which induce Optical signal-to-Noise Ratio (OSNR) degradation and non-linear impairments. Such effect can be alleviated by using Gain-clamped Discrete Raman Fiber Amplifier (GC-DCRFA) which will maintain the gain of the amplifier regardless the input power. The GC-DCRFA in this research work design is realized by utilizing a pair of circulators at the input and output of the amplifier. A portion of counter-propagating amplified spontaneous emission (ASE) is extracted and used to clamp the gain at desired values. The GC-DCRFA is pumped using a pair of 1465 nm Laser Diodes (LD) and input signal wavelength of 1560 nm is used throughout the research work. The GC-DCRFA is also tested using other lasing wavelengths of 1550 nm and 1565 nm. The proposed GC-DCRFA configuration is believed to offer less component losses compared to other amplifier configurations discussed previously. The amplifier characteristics such as the gain and noise figure (NF) are investigated in the research work. The GC-DCRFA is proven to be able to produce a wider dynamic range compared to the conventional DCRFA. For example, at gain of 15 dB, the GC-DCRFA is able to maintain constant gain for input signal, Pin ranges from -25 dBm up to -1.6 dBm with gain variation as of 0.3 dB. On the other hand, the NF is recorded between 5.1 to 6.0 dB. Meanwhile the conventional DCRFA gain starts at 17.8 dB and maintains the gain with the same variation for input signal up to -10 dBm. The effect of adding an Erbium Doped Fiber Amplifier (EDFA) to form a hybrid gain-clamped amplifier configuration is also studied. The hybrid gain-clamped DCRFA/EDFA has wider dynamic range and the availability of maintaining small gain variation. At gain of 15.5 dB, the hybrid gain-clamped DCRFA/EDFA has a dynamic range of between -25 dBm to -1.61 dBm and gain variation of 1.2 dB. Meanwhile for the same dynamic range, the hybrid gain-clamped EDFA/DCRFA generates bigger gain variation of 3.5 dB. However the Noise Figure (NF) seems to be smaller in the hybrid gain-clamped EDFA/DCRFA compared to the other hybrd configuration. The existence of the EDFA seems to influence the dynamic range as it is operating in low pumping regime which causes weak population inversion