Showing papers by "Leimeng Zhuang published in 2011"

Low-loss, high-index-contrast Si3N4/SiO2 optical waveguides for optical delay lines in microwave photonics signal processing

Abstract: We report the design and characterization of Si3N4/SiO2 optical waveguides which are specifically developed for optical delay lines in microwave photonics (MWP) signal processing applications. The waveguide structure consists of a stack of two Si3N4 stripes and SiO2 as an intermediate layer. Characterization of the waveguide propagation loss was performed in race track-shaped optical ring resonators (ORRs) with a free-spectral range of 20 GHz and a bending radius varied from 50 μm to 125 μm. A waveguide propagation loss as low as 0.095 dB/cm was measured in the ORRs with bend radii ≥ 70 μm. Using the waveguide technology two types of RF-modulated optical sideband filters with high sideband suppression and small transition band consisting of an Mach-Zehnder interferometer and ORRs are also demonstrated. These results demonstrate the potential of the waveguide technology to be applied to construct compact on-chip MWP signal processors.

On-chip CMOS compatible reconfigurable optical delay line with separate carrier tuning for microwave photonic signal processing.

Abstract: We report, for the first time, an integrated photonic signal processor consisting of a reconfigurable optical delay line (ODL) with a separate carrier tuning (SCT) unit and an optical sideband filter on a single CMOS compatible photonic chip The processing functionalities are carried out with optical ring resonators as building blocks We show that the integrated approach together with the use of SCT technique allows the implementation of a wideband, fully-tunable ODL with reduced complexity To highlight the functionalities of the processor, we demonstrate a reconfigurable microwave photonic filter where the ODL has been configured in a bandwidth over 1 GHz

Towards a broadband and squint-free Ku-band phased array antenna system for airborne satellite communications

Abstract: In this paper, we describe the design and the development of a K u -band phased array antenna system for the reception of a digital video broadcasting by satellite (DVB-S) signal. A concept of optical beamforming is implemented to provide a squint-free beam steering over the entire Ku-band (10.7–12.75 GHz) as well as to achieve seamless tunability of the beam pointing direction. The total antenna system is described and the system performance is simulated. Requirements for system components are formulated and the development of these components towards the implementation of the broadband, squint-free phased array antenna system is reported.

Separate carrier tuning scheme for integrated optical delay lines in photonic beamformers

Abstract: We implement and experimentally demonstrate the separate carrier tuning technique on an optical ring resonator-based integrated optical delay line. For the first time, the carrier tuner, the delay elements and the optical sideband filter are integrated on the same chip. The proposed approach allows to reduce the complexity of the delay unit and makes the bandwidth independent of the absolute RF frequency. The demonstrated principle can be conveniently employed in any integrated non-coherent optical beamformer system.

Photonic integration and components development for a K u -band phased array antenna system

Abstract: In this paper the development of a phased array antenna system using a photonic beamformer is reported. The paper emphasizes on the photonic integration between two main components of the beamformer, namely the photonic beamformer chip and the electroabsorption modulator array. System level simulation is used to determine the required performance of each component. The measurements on the component characteristics are presented.

Low-loss and programmable integrated photonic beamformer for electronically-steered broadband phased array antennas

Abstract: We have reported the progress of the development of an integrated photonic BFN chip used in a K u -band PAA system. Various test structures and building blocks have been characterized. The realized BFN chip features a waveguide propagation loss lower than 0.2 dB/cm, a bend radius of 125 µm and high design accuracy, fulfilling the required device characteristics.

Development of an integrated photonic beamformer for electronically-steered K u -band phased array antenna

Abstract: Currently an integrated photonic beamformer for electronically-steered K u -band phased array antenna (PAA) system for satellite communications is being developed within a Dutch Point One R&D Innovation Project “Broadband Satellite Communication Services on High-Speed Transport Vehicles”, targeting instantaneous reception of the full K u -band (10.7–12.75 GHz), squint-free and seamless beam steering, and polarization agility. The use of integrated photonic beamformer enables an antenna system with multi-gigahertz instantaneous bandwidth, compact form factor, light weight, and large beam scanning range, which are challenging requirements for beamformers using only electronics-based RF technologies. An important aspect tackled in this project is to reduce the system cost such that it is commercially suitable for civil purposes in mobile satellite communications, particularly in aeronautic/avionic satellite communications where a low profile and light weight are essential requirements for the antenna system. The core of the photonic beamformer consists of an optical ring resonator (ORR) filter-based beamforming network (BFN). ORR filters are capable to provide continuously tunable true time delays (TTDs) with configurable bandwidth, and serve as delay elements in a BFN allowing squint-free and seamless beam steering for gigahertz bandwidth applications [1], [2]. Therefore, this approach is superior to the BFNs using phase shifters, discrete time delays or digital BFNs. This photonic beamformer also features optical single-sideband suppressed-carrier modulation and coherent optical detection techniques, resulting in reduced number of ORRs in the BFN [1], [2]. Other system components such as the optical sideband filter, optical signal combining and carrier reinsertion circuitry are integrated with the ORRs in one photonic BFN chip. In the past, a laboratory demonstrator of such an antenna system has been realized as a proof-of-concept, incorporating individually packaged components, such as LNBs and optical modulators [2]. Currently, there is a large effort in the development of the key components, namely front-end, optical modulator, and photonic BFN, and the integration between them, aiming for the actual deployment of the antenna system.