The use of photonic heterodyne receivers based on semiconductor optical amplifiers to be used in imaging arrays at several GHz frequencies is evaluated. With this objective, a imaging array based on such photonic pixels has been fabricated and characterized. Each of the receiving optoelectronic pixels is composed of an antipodal linear tapered slot antenna (LTSA) that sends the received RF signal directly to the electrical port of a semiconductor opticalamplifier (SOA) acting as the optoelectronic mixer. Both the local oscillator (LO) and the intermediate frequency (IF) signals are directly distributed to/from the array pixels using fiber optics, that allows for remote LO generation and IF processing to recover the image. The results shown in this work demonstrate that the performances of the optoelectronic imaging array are similar to a reference all-electronic array, revealing the possibility of using this photonic architecture in future high-density, scalable, compact imaging arrays in microwave and millimeter wave ranges. 1. Introduction Microwave photonics and radio-over-fiber (RoF) techniques have been used in antenna arrays for some years now typically associated with local oscillator (LO) distribution and remote intermediate frequency (IF) processing [1]. The advantages usually associated with the use of such techniques are the high bandwidth capabilities, the electromagnetic interference (EMI) immunity, the extremely low transmission losses when using optical fibers, and the possibilities of including signal processing features, like true local time delay (TTD) [2] or optical beam forming [3]. Their advantages are also associated with the availability of optical/photonic devices in the telecom wavelength range which, due to the growth of the optical communications in the last decades, provide us with high-performance, wide-variety, compact, and low-cost (COTS) optical components suitable for its use in microwave photonics and RoF. Following this trend, new functionalities based on photonic processing of RF are becoming available to be incorporated into arrays beyond optical signal distribution. In this sense, a major contribution to obtain high-density receiving arrays based on photonic techniques would be the obtaining of a photonic heterodyne receiver able to perform directly the mixing of the LO (photonically distributed) and the received RF with high sensitivity. This all-optical pixel would reduce the several electrooptical (EO) conversions typical to conventional RoF systems and would be able to be integrated directly into the mature
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