Lefteris Gounaridis

TL;DR: In this paper, an extensive analysis of an optical Blass-matrix architecture as a beamforming network with potential for multibeam operation in wireless systems is presented, which relies on the use of phase shifters and Mach-Zehnder Interferometers (MZIs) inside an $M\times N$ matrix, and enables the generation of M beams by N -element antenna arrays.

Abstract: We demonstrate a broadband and continuously tunable 1×4 optical beamforming network (OBFN), based on the hybrid integration of indium phosphide (InP) components in the silicon nitride (Si3N4) platform. The photonic integrated circuit (PIC) comprises a hybrid InP-Si3N4 external cavity laser, a pair of InP phase modulators, a Si3N4 optical single-sideband full carrier (SSBFC) filter followed by four tunable optical true time delay lines (OTTDLs), and four InP photodetectors. Each OTTDL consists of eight cascaded thermo-optical micro-ring resonators (MRRs) that impose tunable true time delay on the propagating optical signals. The OBFN-PIC is designed to facilitate the steering of a microwave signal with carrier frequency up to 40 GHz over a continuous set of beam angles. We evaluate the performance of the OBFN-PIC to handle and process microwave signals, measuring the link gain, the noise figure (NF), and the spurious-free dynamic range (SFDR) parameters. Moreover, we assess its beamforming capabilities assuming that the OBFN-PIC is part of a wireless system operating in the downlink direction and feeds a multi-element antenna array. Using microwave signals at 5 and 10 GHz with quadrature amplitude modulation (QAM) formats at 500 Mbaud, we evaluate the performance of the OBFN-PIC under various configurations. We show that error-free performance can be achieved at both operating frequencies and for all the investigated beam angles ranging from 45° to 135°, thus validating its potential for high-quality beamforming performance.

TL;DR: Experimental results regarding the Fast Fourier Transform method for the calculation of the resonance shifts in biosensors based on micro-ring resonators (MRRs) find that the performance is improved by a factor of 2 when the authors go from single- to four-peak transfer functions, and that the impact of the wavelength dependence of the laser power is very low.

TL;DR: A monolithic integration of a multimode interference coupler with two Mach-Zehnder modulators on an electro-optic polymer chip and the hybrid integration of this chip with an InP laser diode and two multiplexing and driving circuits provides significant advantages in number of components, simplicity, footprint, and cost.

TL;DR: Through the analysis of the expected radiation pattern and off-line measurements of the BER of the decoded signals at the intended steering angles, the feasibility of the proposed optical beamforming network (OBFN) is validated.