W.C. van Etten

Novel Ring Resonator-Based Integrated Photonic Beamformer for Broadband Phased Array Receive Antennas—Part I: Design and Performance Analysis

A novel optical beamformer concept is introduced that can be used for seamless control of the reception angle in broadband wireless receivers employing a large phased array antenna (PAA). The core of this beamformer is an optical beamforming network (OBFN), using ring resonator-based broadband delays, and coherent optical combining. The electro-optical conversion is performed by means of single-sideband suppressed carrier modulation, employing a common laser, Mach-Zehnder modulators, and a common optical sideband filter after the OBFN. The unmodulated laser signal is then re-injected in order to perform balanced coherent optical detection, for the opto-electrical conversion. This scheme minimizes the requirements on the complexity of the OBFN, and has potential for compact realization by means of full integration on chip. The impact of the optical beamformer concept on the performance of the full receiver system is analyzed, by modeling the combination of the PAA and the beamformer as an equivalent two-port RF system. The results are illustrated by a numerical example of a PAA receiver for satellite TV reception, showing that - when properly designed - the beamformer hardly affects the sensitivity of the receiver.

Single-Chip Ring Resonator-Based 1

Optical ring resonators (ORRs) are good candidates to provide continuously tunable delay in optical beam forming networks (OBFNs) for phased array antenna systems. Delay and splitting/combining elements can be integrated on a single optical chip to form an OBFN. A state-of-the-art ring resonator-based 1times 8 OBFN chip has been fabricated in complementary metal-oxide-semiconductor-compatible waveguide technology. A binary tree topology is used for the network such that a different number of ORRs is cascaded for delay generation at each output. In this letter, the principle of operation is explained and demonstrated by presenting some measurement results on the 1times 8 OBFN chip.

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A novel beam steering mechanism for a phased array antenna receiver system is introduced. The core of the system is a ring resonator-based integrated optical beam forming network chip. Its principles are explained and demonstrated by presenting some measurement results. The system architecture around the chip is based on a combination of frequency down conversion, filter-based optical single sideband modulation and balanced coherent detection. It is proven that such an architecture has significant advantages with respect to a straightforward architecture using double sideband modulation and direct detection, namely relaxed bandwidth requirements on the optical modulators and detectors, reduced complexity and optical losses of the beam forming chip, and enhanced dynamic range

8 Optical Beam Forming Network in CMOS-Compatible Waveguide Technology

Optical ring resonators (ORRs) can be used as continuously tunable delay elements in a beam forming network for a phased-array antenna system. The bandwidth of such delay elements can be enhanced by cascading multiple ORRs. When delays and splitting/combining circuitry are integrated in one optical circuit, an optical beam forming network (OBFN) is obtained. In this paper, the principles of optical beam forming using ORRs are explained and demonstrated, by presenting measurements on a 1times4 OBFN chip, realized in LPCVD waveguide technology. To our knowledge, this is the first single-chip demonstration of continuous optical beam forming

Phased Array Antenna Steering Using a Ring Resonator-Based Optical Beam Forming Network

For enhanced communication on board an aircraft, novel antenna systems with broadband satellite-based capabilities are required. The technology will enhance airline operations by providing in-flight connectivity for flight crew information and will bring live TV and highspeed Internet connectivity to passengers. The installation of such systems on board an aircraft requires for aerodynamic reasons the development a very low-profile aircraft antenna, which can point to satellites anywhere in the upper hemisphere. To this end, phased array antennas which are conformal to the aircraft fuselage are attractive. In this paper, two key aspects of conformal phased array antenna arrays are addressed: the development of a broadband Ku-band antenna and an optical beam forming network for tracking satellites. The antenna elements of the conformal array are stacked patch antennas with dual linear polarization which have sufficient bandwidth. For tracking an optical circuit is proposed that consists of a cascade of optical ring resonators.

Single-chip optical beam forming network in LPCVD waveguide technology based on optical ring resonators

For enhanced communication on board aircraft, novel antenna systems with broadband satellite-based capabilities are required. The technology will enhance airline operations by providing in-flight connectivity for flight crew information and will bring live TV and high-speed Internet connectivity to passengers. The installation of such systems on board aircraft requires for aerodynamic reasons the development a very low-profile aircraft antenna, which can point to satellites anywhere in the upper hemisphere. Major keystones for the success of steerable low-profile antennas are multi-layer printed circuit boards (PCBs) with an array of broadband antenna elements, and compact micro-wave systems with appropriate beam steering capabilities. The present paper describes the development of a prototype 8x1 optical beam forming network using cascades of optical ring resonators as part of a breadboard Ku-band phased array antenna.

Broadband Conformal Phased Array with Optical Beam Forming for Airborne Satellite Communication

A squint-free, continuously tunable optical beamformer system for phased array receive antennas is proposed and experimentally demonstrated, which involves an integrated ring resonator-based optical beam forming network, filter-based optical SSB-SC modulation and balanced coherent detection.

Broadband optical beam forming for airborne phased array antenna

In this paper a novel CW laser-compatible, squint-free, continuously tunable ring resonator-based optical beamformer mechanism for a phased array receiver system is proposed and partly demonstrated. When the optical delay elements and optical signal processing circuitry are integrated on a chip, a single-chip optical beam forming network (OBFN) is obtained. The optical delay elements are ideally continuously tunable to achieve continuous control of the beam direction, and should have a flat delay and magnitude response over the signal band, to avoid distortion. In the proposed system architecture, filter-based optical single-sideband suppressed-carrier modulation and balanced coherent optical detection are used. Such architecture has significant advantages over a straightforward architecture using optical intensity modulation and direct optical detection, namely reduced complexity of the OBFN chip, and enhanced dynamic range. Measurements on an actual 1×8 OBFN chip and an optical sideband filter chip are presented. Both are realized in CMOS-compatible planar optical waveguide technology (TriPleX).

Novel ring resonator-based optical beamformer for broadband phased array receive antennas

An optical phase synchronization system using a power feedback loop technique is experimentally demonstrated. The system allows coherent combining of signals modulated on the same optical carrier in a hybrid optical beam forming system setup.

Integrated photonic beamformer employing continuously tunable ring resonator-based delays in CMOS-compatible LPCVD waveguide technology

A broadband, continuously tunable receiver system for phased array antennas is described. It uses a ring resonator-based optical beamforming network, filter-based optical SSB-SC modulation and balanced coherent detection. The system is modeled as an equivalent RF two-port system and its performance is analyzed, identifying and modeling dominant noise and distortion sources. Numerical theoretical performance results are reported for a satellite television case study, based on DVB-S.