RESUMO
A simplified millimeter-wave (mm-wave) radio-over-fiber (RoF) system employing a combination of optical heterodyning in signal generation and radio frequency (RF) self-homodyning in data recovery process is proposed and demonstrated. Three variants of the system are considered in which two independent uncorrelated lasers with a frequency offset equal to the desired mm-wave carrier frequency are used to generate the transmitted signal. Uncorrelated phase noise in the resulting mm-wave signal after photodetection was overcome by using RF self-homodyning in the data recovery process. Theoretical analyses followed by experimental results and simulated characterizations confirm the system's performance. A key advantage of the system is that it avoids the need for high-speed electro-optic and electronic devices operating at the RF carrier frequency at both the central station and base stations.
Assuntos
Modelos Teóricos , Fibras Ópticas , Telecomunicações/instrumentação , Transdutores , Simulação por Computador , Desenho Assistido por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Micro-Ondas , Ondas de RádioRESUMO
We present experimentally feasible designs of a dual-core microstructured polymer optical fiber (mPOF), which can act as a highly sensitive, label-free, and selective biosensor. An immobilized antigen sensing layer on the walls of the holes in the mPOF provides the ability to selectively capture antibody biomolecules. The change of the layer thickness of biomolecules can then be detected as a change in the coupling length between the two cores. We compare mPOF structures with 1, 2, and 3 air-holes between the solid cores and show that the sensitivity increases with increasing distance between the cores. Numerical calculations indicate a record sensitivity up to 20 nm/nm (defined as the shift in the resonance wavelength per nm biolayer) at visible wavelengths, where the mPOF has low loss.
Assuntos
Antígenos/química , Técnicas Biossensoriais , Fibras Ópticas , Óptica e Fotônica , Polímeros/química , Campos Eletromagnéticos , Modelos Estatísticos , Modelos Teóricos , Polimetil Metacrilato/química , Reprodutibilidade dos Testes , Água/químicaRESUMO
A short linear cavity erbium fiber laser is adapted to become a Q-switched laser by using a new and simple loss switching technique. The technique utilizes the inherent flexibility of optical fiber to rapidly drive the fiber end in and out of alignment with a cavity mirror, creating the conditions necessary for Q-switching. We investigate the effectiveness of different Q-switch configurations and analyze the Q-switch opening time of each configuration.
RESUMO
We describe a dual-core microstructured optical fiber designed for refractive index sensing of fluids. We show that by using the exponential dependence of intercore coupling on analyte refractive index, both large range and high sensitivity can be achieved in the one device. We also show that selective filling of the microstructure with analyte can increase the device sensitivity by approximately 1 order of magnitude.
RESUMO
Noise reduction in a multiwavelength distributed Bragg reflector fiber laser was demonstrated. A 20 dB reduction of in-phase intensity noise was achieved by using negative feedback to modulate the drive current of the laser pump diode. Strategies for reducing antiphase noise components are discussed.