A reconfigurable optical FIR filter based on delay interference structure is proposed, which can realize band-pass and band-stop filtering. The interference structure is mainly composed of an adjustable beam splitter based on Mach-Zehnder interferometer(MZI) structure and a delay line with a phase shifter. Light can be guided to four paths that have different delays and different optical transmission spectrum can be achieved by tuning the amplitude and phase of the four paths by tuning the phase shift of the MZI and delay line. To optimize the transmission spectrum, the theoretical model of the delay interference filter is established and simulated by the transmission matrix method. The simulation results show that the extinction ratio of band-pass filter is greater than 15dB, the extinction ratio of band-stop filter is greater than 40dB, and the in-band fluctuation is lower than 1.5dB.
KEYWORDS: Switches, Digital signal processing, Silicon, Control systems, Palladium, Optical fibers, Modulators, Signal attenuation, Photodetectors, Waveguides
We proposed a novel automatic approach for tuning automatically different delay in a 7-bit silicon-based optical delay line. The measured results of delay line by automatic tuning are also given and compared with the design values.
KEYWORDS: Modulation, Single sideband modulation, Radio over Fiber, Double sideband modulation, Signal detection, Singular optics, Signal to noise ratio, Scattering, Dispersion, Radio optics
Stimulated Brillouin scattering in fiber is used to realize optical single sideband modulation of the 11GHz radio over fiber (RoF) system. It amplifies the lower sideband of modulated signals and attenuates the upper sideband. Optical single sideband modulation is then achieved which reduces the dispersion caused by traditional double sideband modulation in RoF system. The performance of 11GHz RoF system is then improved. In the experiment, about 2dB SNR gain is attained at 10Mbit/s signal with QPSK modulated format.
KEYWORDS: Modulation, Signal attenuation, Scattering, Radio over Fiber, Single mode fibers, Optical fibers, Optical amplifiers, Signal detection, Optical filters, Optical engineering
simple and efficient technique based on stimulated Brillouin scattering is proposed to reduce RF loss in radio-over-fiber systems. The modulation depth and RF signal gain increase with the power of the input modulated signal. A modulation depth of 100% can be easily attained at a lower input power. The experimental results are in good agreement with the theoretical predictions. Approximately 26 dB of RF signal gain in the band from 1 to 18 GHz is achieved in the experiment with this technique. Finally, the transmission experiment shows that this technique can effectively improve the performance of radio-over-fiber systems.
KEYWORDS: Modulation, Signal attenuation, Radio over Fiber, Single mode fibers, Optical filters, Scattering, Microwave photonics, Signal detection, Electronic filtering, Optical amplifiers
A long fiber ring as the simple filter for carrier- suppression of microwave photonics signals is proposed. It is based on stimulated Brillouin scattering. The filter can be used to reduce RF loss in radio on fiber system. The modulation depth and RF signal gain increase with the power of input modulated signal. A modulation depth of 100% can be easily attained at a lower input power. The experimental results are well in agreement with the theoretical predictions. Approximately 26 dB of RF signal gain in the band from 1 GHz to 18GHz is achieved in the experiment with this technique. Finally, the transmission experiment shows that the performance of radio on fiber system is effectively improved with the filter.
Optical burst switching (OBS) is a viable solution to support next generation optical Internet. This paper addresses the problem of inter-class bandwidth management for OBS supporting multi-class services. Bandwidth management should be simple to implement and optimally designed to maximize the network performance. We propose here a wavelength based inter-class bandwidth management approach for optical burst switched networks (OBSN). Three different wavelength allocation schemes are presented respectively. In our schemes, each class of service is endued with a weight according to its importance, which is proportional to the charge on corresponding class of service by the network operator. The static scheme allocates wavelengths based on the weight of class, while the dynamic allocation scheme is based on the weighted traffic load with the help of a traffic predictor. The merit optimized allocation aims to achieve the maximized weighted throughput of the network based on a traffic predictor and a dynamic optimization algorithm. The performance of the proposed three schemes are evaluated and compared by computer simulations, where the weighted loss rate is chosen to be a merit used in performance evaluations. From the viewpoint of the network operator, the merit-based scheme provides the maximized profit since it improves the weighted throughput of the system, which is approved by simulation results.
A novel organic electroluminescent device with EuGd complex (Eu0.1Gd0.9)(TTA)3(TPPO)2 as an emitter is presented, and the characteristics of the device are investigated. The phosphorescence emission from the device are observed, which are discussed in terms of yields of phosphorescence from the triplet excited state of the Gd and Eu chelates due to the strong protuberance to the spin-orbit levels of the ligands by the paramagnetic Gd3+ ions. Both the photoluminescent and electroluminescent efficiencies at different temperature between 77 K and 300 K are measured by integrating sphere method. Our results show that the phosphorescent emission from the triplets excited sate might be useful to improve the quantum efficiency of organic electroluminescent devices.
We present here the experimental and numerical results to demonstrate the superior performance of optical wavelet transform correlator over conventional Fourier transform correlator. For this purpose the biomolecular material, Bacteriorhodopsin, as the recording media and the improved dual-axis joint transform correlator configuration as the preferred optical setup have been used. Compared with the dual-axis joint Fourier transform correlator, the dual-axis joint wavelet transform correlator provides better correlation performance.
The polymeric cross-linked hydrogel doped with dye 4- nitroaniline was prepared. The nonlinear optical properties of this material has been studied. The optical storage effects and the dynamic lens effects in this dye doped hydrogel under laser radiation have been observed. It is reasonable to show that this dye doped polymer get will find some applications in optical signal processing.
We report an observation of optical phase conjugate and high-order diffractions from degenerate multi-wave mixing in LB films of pure purple membrane for the first time. Based on the simplified BR photocycle, a model that describes the high-order diffractions from the population gratings versus the total incident intensity has been developed. The saturated absorption intensity and the saturated nonlinear refractive index of the LB films have been estimated by fitting method to be 0.42 W/cm2, and 5 X 10-2 cm2W, respectively. The typical response time of its nonlinearity is about several milliseconds.
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