Design of a Highly Sensitive Photonic Crystal Fiber Sensor for Sulfuric Acid Detection

In this research, a photonic crystal fiber (PCF)-based sulfuric acid detector is proposed and investigated to identify the exact concentration of sulfuric acid in a mixture with water. In order to calculate the sensing and propagation characteristics, a finite element method (FEM) based on COMSOL Multiphysics software is employed. The extensive simulation results verified that the proposed optical detector could achieve an ultra-high sensitivity of around 97.8% at optimum structural and operating conditions. Furthermore, the proposed sensor exhibited negligible loss with suitable numerical aperture and single-mode propagation at fixed operating conditions. In addition, the circular air holes in the core and cladding reduce fabrication complexity and can be easily produced using the current technology. Therefore, we strongly believe that the proposed detector will soon find its use in numerous industrial applications

Performance Enhancement of Ytterbium-Doped Fiber Amplifier Employing a Dual-Stage In-Band Asymmetrical Pumping

The performance of doped fiber amplifiers can be enhanced significantly with the help of multi-stage pumping technique provided that various critical parameters of pumps including their optical power and wavelength are optimized. We report the performance enhancement of a ytterbium doped fiber amplifier (YDFA) for a 1.02–1.08 μm spectral region with an optimized design based on a novel dual-stage in-band asymmetrical pumping scheme. By accurately adjusting the optical power and wavelength of pumps in both the stages, a record peak gain of around 62.5 dB and output power of 4.5 W are achieved for a signal wavelength of 1.0329 μm at an optimized length of Ytterbium-doped silica fiber and optimized doping concentration of Yb3+. Moreover, a minimum noise figure (NF) of 4 dB is observed for a signal wavelength of 1.0329 μm at the optimized parameters. Similarly, the effect of using high and low pump powers at the first and the second stage, respectively, on NF of the amplifier is also investigated at different values of signal powers. It is observed that the value of NF increases significantly by using high pump power at the first stage and low pump power at the second stage

Design of an efficient thulium-doped fiber amplifier for dual-hop earth to satellite optical wireless links

Optical wireless communication (OWC) links enable high-speed data transmission between earth stations and satellites. The propagation of optical signals through the atmosphere suffer from atmospheric attenuation and turbulence due to rain, fog, snow, clouds, and wind. The impact of these impairments on propagation of optical signals becomes more pronounced in the case of deep space links. Therefore, optical amplifiers of high output power and gain are extremely useful in deep space links to achieve error free transmission by improving the link budget. In this paper, we propose the design of an efficient Thulium-doped fiber amplifier (TDFA) as booster as well as an in-line based on dual-stage pumping scheme for employment in a dual-hop earth to satellite OWC Link. The pumping scheme, length of Thulium-doped fiber (TDF), and Tm3+ concentration in the proposed design of TDFA are optimized in such a way so that high output power and gain are achieved for booster and in-line stages, respectively. Output power and gain of 4.6 W and 18.8 dB, respectively are achieved for signal power of 0 dBm at 1807.143 nm when TDFA is used as booster amplifier. Similarly, gain and output power of 66.6 dB and 1.5 W, respectively are achieved for signal power of −35 dBm at 1807.143 nm when TDFA is used as in-line amplifier. A noise figure (NF) of 4.4 dB is achieved for signal wavelength of 1807.143 nm and power of 0 dBm. Finally, the system level performance of the designed TDFA is investigated using bit error rate (BER) metric for a dual-hop earth to satellite OWC wavelength division multiplexed (WDM) transmission system of four quadrature phase shift keying (QPSK) modulated optical signals with an aggregate data rate of 104 Gbps. The BER results showed different possible ranges of error-free transmission at the forward error correction (FEC) limit of 10-4 for different values of atmospheric attenuation