Advanced Materials Research Vols. 760-762

Abstract: Two wideband bandpass filters with miniature size and wide stopband are proposed by using cascaded U-shaped resonators. The filters exhibit bandwidths of 31.1% and 28.8% at about 5.3GHz and 5.6GHz, respectively. Both designed filters have simple structures and compact sizes, wide passband, excellent out-band performance with wide lower and upper stopbands, and a pair of transmission zeros on both sides of passband. The new designs have evident circuit size reduction compared with relative reports. A wideband microstrip BPF is fabricated and measured, and the measurement exhibits good agreement with the prediction.

Abstract: New ultra-wideband (UWB) bandpass filters are proposed by using stepped-impendence resonators (SIRs) and stub-loaded SIRs, aiming at transmitting the signals in the whole UWB passband of 3.1GHz-10.6GHz. Each of the proposed UWB filters consists of two parallel but oppositely arranged compact SIR with tri or quad-section or stub-loaded SIR. In the design, the first two or three resonances of the proposed resonators are properly adjusted to be placed within the UWB. In order to enhance the coupling degree, pairs of quarter-wavelength parallel-coupled lines are longitudinally stretched in both the input and output sides. The UWB bandpass filters behave multiple transmission poles and good return loss of no less than 15dB. A proposed UWB filter is fabricated and measured, and the experiment demonstrates the design.

Abstract: In this article,the transmission spectra of ten-fold photonic quasicrystals (PQC) are calculated by using finite-difference time-domain method (FDTD). By changing the crystal structure and introducing the point and line defects to devise the good micro-cavity and waveguide structures.In TE mode, the transmission spectra with defect modes are observed and quality (Q) factors are calculated to optimize the micro-cavity structure.It has the biggest Q factor when the central dielectric cylinder is removed. Furthermore, Design different waveguide structures and explore the field distribution. Different waveguide structure can control different light path and choose different incident light frequency.

Abstract: The focal length of the lens in the spatial filter should simultaneously satisfy the requirement of vacuum and the minimum spherical aberration. In order to filter the high frequency components, the divergence angle of the filter must be less than a certain value according to the system requirement. So the aperture of the filter hole used in the high power laser system is about 20 times of the diffraction limitation. At the same time, the scope of the location of the filter hole in the optical axis is reasonable as long as the location within the focal depth. In addition, the model was built by means of the optical design software to simulate validation. The simulation results show that the designed spatial filter according to the method presented in the paper can effectively filter out the high frequency components and stray light in the system.

Abstract: The letter proposes a novel Optical Network Units (ONUs) source-free scheme for Orthogonal Frequency Division Multiple (OFDM)-based passive optical networks (PON), in which an optical frequency comb generator built by a conventional Mach-Zehnder modulator (MZM) is used to generate ultra-flat optical frequency comb spectra for the downstream and upstream transmission. The proposed architecture is presented and simulated to achieve simultaneously upstream transmission from multiple ONUs over the fiber. Simulation results show the receiver sensitivity reaches-18dBm for upstream transmission and-18.75dBm for downstream transmission.

Abstract: This paper introduces the research and design of a certain type of UAV optical electronics sensors battle operation training laboratory based on VR technology. It expatiates the function and structure of the lab. The lab can solve the critical problems faced by present real UAV equipment battle education training and improve training effect distinctly. The lab also can help cadets to inquire and learn more knowledge and skill effectively.

Abstract: Degree of polarization (DOP) is an important physical quantity for describing the optical polarization effect and is widely applied in optical fiber communication, optical fiber gyro and the related technologies. In this paper, the polarization beam combination method is raised to research and manufacture the standard optical fiber light source device with the variable DOP, and an indicated error measurement has been conducted for a DOP meter.

Abstract: In this paper, we presented an improved equalization algorithm which use Least Mean Square algorithm (LMS) training-based as pre-convergence, after reaching the threshold, equalization switches to directed decision LMS to compensate a various of impairs and decrease bit error rate (BER) to achieve better performance in the steady-state, the experiment is based on a 28GbaudMQAM polarization multiplexing optical coherent system.

Abstract: A tunable filter was designed, which using the liquid crystal as defect films based on the one-dimensional ternary photonic crystal. The spectrum transmission was obtained by using the transfer matrix method, analyze the properties of the band gap of the 1D ternary photonic crystal and main factors influencing the tunable filter. The results show that the filter has different job windows by changing the thickness increment of the adjacent medium behind the liquid crystal, and the tuning range of which has 30nm and above .

Abstract: The temperature stability of scale factor (SF) has been analyzed and tested systematically for an optical voltage sensor (OVS) based on Pockels effect in this paper. The cardinal temperature sensitive parameters in sensor head and their impacts on SF are brought out by theoretical analysis and simulation method. Corresponding experiments are arranged to verify the validity of theoretical analysis. A real-time temperature compensation system is fabricated to reduce the error of SF in temperature fluctuation environment and its effectiveness is certified by experiment.