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61.
We experimentally demonstrate an all-optical 10 Gb/s format conversion from non-return-to-zero (NRZ) on-off-keying (OOK) to return-to-zero (RZ)-OOK with tunable duty cycle in the whole C-band using nonlinear polarization rotation (NPR) arising in an semiconductor optical amplifier (SOA). The experimental results show that, by tuning the polarizer at the SOA output, an RZ signal with tunable duty cycle from 33% to 66% could be obtained with an extinction ratio(ER) over 10 dB. In addition, we show that the NRZ-to-RZ conversion with duty cycle of 33-66% can be obtained with less than 1 dB power penalty at the bit error ratio (BER) of 10−9. The device can facilitate the cross-connection between optical transmission networks employing different modulation formats. 相似文献
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Exploiting continuity properties of Fourier multipliers on modulation spaces and Wiener amalgam spaces, we study the Cauchy problem for the NLW equation. Local wellposedness for rough data in modulation spaces and Wiener amalgam spaces is shown. The results formulated in the framework of modulation spaces refine those in [A. Bényi, K.A. Okoudjou, Local well-posedness of nonlinear dispersive equations on modulation spaces, preprint, April 2007 (available at ArXiv:0704.0833v1)]. The same arguments may apply to obtain local wellposedness for the NLKG equation. 相似文献
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The paper presents investigation results concerning band structure of gallium nitride and position of intrinsic and associate defect levels. Main optical characteristics (transmission, reflection and luminescence) were measured in both ordinary and λ-modulation mode for epitaxy-grown GaN films, allowing to determine valence band splitting caused by spin-orbital interaction (48 meV) and crystalline field (10 meV). Analysis of photoluminescence spectra made it possible to identify main recombination mechanisms involving donor and acceptor levels formed by intrinsic point defects , and their associates. 相似文献
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The future wireless communication will come up with a strict requirement on high spectral efficiency, developing novel algorithms for spectrum sensing with deep sensing capability will be more challenging. However, traditional expert feature-based spectrum sensing algorithms are lack of sufficient capability of self-learning and adaptability to unknown environments and complex cognitive tasks. To address this problem, we propose to build up a deep learning network to learn short time-frequency transformation (STFT), a basic entity of traditional spectrum sensing algorithms. Spectrum sensing based on the learning to STFT network is supposed to automatically extract features for communication signals and makes decisions for complex cognitive tasks meanwhile. The feasibility and performances of the designed learning network are verified by classifying signal modulation types in deep spectrum sensing applications. 相似文献
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为了完成飞行器导引头目标识别与探测任务,以短焦距、大视场进行搜索并确认目标,以长焦距、小视场进行高精度目标识别。通过选择正组补偿的机械补偿法,采用3种普通光学材料,在长焦距位置,将前固定组、变倍组的组合设计为远摄型,使得系统结构紧凑,满足导引头小型化的要求。利用CODE V光学设计软件,优化设计了焦距为30~150 mm,视场角为12.90°×10.25°~2.59°×2.07°,筒长仅为174 mm的变焦距光学系统,得到成像质量优良的设计结果。各焦距、全视场平均传递函数值在50 lp/mm时为0.695,测试结果为0.562,满足系统的性能要求。 相似文献