Adam Raptakis

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: The reported results suggest that in a fixed C-band grid, the spectral isolation between classical and quantum channels is essential at dense grids and the photons linked with the Raman scattering become the dominant noise source.

TL;DR: In this paper, the authors proposed a novel concept for the implementation of 2D optical phased arrays (OPAs) with end-fire waveguides as antenna elements (AEs), and presented its theoretical model and experimental proof.

TL;DR: In this paper, a photonic integrated circuit (PIC) is used as an optical equalizer (OE) with multi-rate and multi-channel capability, based on the use of micro-ring resonators (MRRs) for the tuning of its delay lines.

TL;DR: This paper verifies the intrinsic capability of optical beamforming networks (OBFNs) to support simultaneously multi-beam and multicast operations and experimentally assess the performance of a $1\times 4$ TTD-OBFN based on commercially available components in the case of multicast operation.