Microwave photonics (MWP) is an emerging field in which radio frequency (RF) signals are generated, distributed, processed and analyzed using the strength of photonic techniques. It is a technology that enables various functionalities which are not feasible to achieve only in the microwave domain. A particular aspect that recently gains significant interests is the use of photonic integrated circuit (PIC) technology in the MWP field for enhanced functionalities and robustness as well as the reduction of size, weight, cost and power consumption. This article reviews the recent advances in this emerging field which is dubbed as integrated microwave photonics. Key integrated MWP technologies are reviewed and the prospective of the field is discussed.

Integrated microwave photonics

Integrated microwave photonics, an emerging technology combining radio frequency (RF) engineering and integrated photonics, has great potential to be adopted for wideband analog processing applications. However, it has been a challenge to provide photonic integrated circuits with equal levels of function flexibility as compared with their electronic counterparts. Here, we introduce a disruptive approach to tackle this need, which is analogous to an electronic field-programmable gate array. We use a grid of tunable Mach–Zehnder couplers interconnected in a two-dimensional mesh network, each working as a photonic processing unit. Such a device is able to be programmed into many different circuit topologies and thereby provide a diversity of functions. This paper provides, to the best of our knowledge, the first ever demonstration of this concept and shows that a programmable chip with a free spectral range of 14 GHz enables RF filters featuring continuous, over-two-octave frequency coverage, i.e., 1.6–6 GHz, and variable passband shaping ranging from a 55 dB extinction notch filter to a 1.6 GHz bandwidth flat-top filter.

https://ris.utwente.nl/ws/files/6955872/optica-2-10-854.pdf

Programmable photonic signal processor chip for radiofrequency applications

We present an overview of several microwave photonic processing functionalities based on combinations of Mach-Zehnder and ring resonator filters using the high index contrast silicon nitride (TriPleXTM) waveguide technology. All functionalities are built using the same basic building blocks, namely straight waveguides, phase tuning elements and directional couplers. We recall previously shown measurements on high spurious free dynamic range microwave photonic (MWP) link, ultra-wideband pulse generation, instantaneous frequency measurements, Hilbert transformers, microwave polarization networks and demonstrate new measurements and functionalities on a 16 channel optical beamforming network and modulation format transformer as well as an outlook on future microwave photonic platform integration, which will lead to a significantly reduced footprint and thereby enables the path to commercially viable MWP systems

/pdf/silicon-nitride-microwave-photonic-circuits-3gjnt2sl30.pdf

Silicon nitride microwave photonic circuits

A system and method for antenna optimization for wireless broadband communication is provided. Such an enhanced antenna array includes higher-gain antenna and lower-gain antenna. The beamforming antenna, both higher-gain and lower-gain, are designed to be able to transmit to and receive from another transceiver. The higher-gain antenna may be designed to form a more directional beam substantially closer to the horizon; whereas the lower-gain antenna is capable of forming a less directional beam at a distance further from the horizon. In both cases, the antenna may form their respective beams anywhere in the 360 degrees horizontally around the antenna array. The higher-gain antenna may include a coverage area from the horizon to a substantially acute angle from the horizon in the vertical direction. In contrast, the lower-gain antenna may have coverage from the substantially acute angle from the horizon to substantially vertical. The substantially acute angle may be approximately 10 degrees in some cases. In some cases the lower-gain antenna may include four elements. Likewise, in some embodiments, the higher-gain antenna may include four elements as well.

System and methods for antenna optimiazation for wireless broadband communication

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.

/pdf/novel-ring-resonator-based-integrated-photonic-beamformer-4uwbu47wu3.pdf

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

For enhanced communication on board of aircraft novel antenna systems with broadband satellite-based capabilities are required. The installation of such systems on board of aircraft requires the development of 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 the beam synthesis for conformal array antennas. The antenna elements of the conformal array are stacked patch antennas with dual linear polarization which have sufficient bandwidth. For beam forming synthesis a method based on a truncated singular value decomposition is proposed.

/pdf/conformal-phased-array-with-beam-forming-for-airborne-2mk1zh192f.pdf

Conformal phased array with beam forming for airborne satellite communication

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.

/pdf/broadband-conformal-phased-array-with-optical-beam-forming-q7kafl2tn2.pdf

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

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 optical beam forming for airborne phased array antenna

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.

P. Jorna

Papers

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

Conformal phased array with beam forming for airborne satellite communication

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

Broadband optical beam forming for airborne phased array antenna

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