Widely Tunable RF Signal Generation Using an InP/Si₃N₄ Hybrid Integrated Dual-Wavelength Optical Heterodyne Source

Abstract

Photonics-based techniques spearhead the generation of high-frequency signals in the millimeter-andTerahertz wave, crucial for ultrabroadband mobile wireless link development. Photonic integration is enabling to provide the photonic approach with added advantages of energy-efficiency, flexibility and scalability, in addition to signal quality. We present an optical heterodyne system based on a novel dual laser module containing two InP-Si 3 N 4 hybrid lasers with intracavity wavelength selective optical filters with output optical power per laser of up to 15 dBm (31 mW), wide wavelength tuning of about 60 nm, and narrow optical linewidth below 100 kHz. To the best of our knowledge, we present for the first time the continuous-wave generation of RF frequencies over a wide tuning range from C-band (4 GHz -8-GHz) to W-band (75 GHz -110 GHz) achieving record low RF electrical linewidth around 108 kHz and long-term drift < 12 MHz with two free-running lasers. This is the best beat-note linewidth obtained with such an integrated source in a free-runnning regime and with a wide tuning range ever reported.Index Terms-photonic integration, millimeter-waves, hybrid laser, laser tuning. I. INTRODUCTIONT is expected that networks will utilize frequency bands in the millimeter-wave range (30 to 300 GHz) to deliver extreme link capacities and miniaturize transceivers [1]. These are key parameters to unlock the radio access densification in urban scenarios through wireless backhaul of small cells,

Injection Locking Properties of an Dual Laser Source for mm-Wave Communications

“…1 shows the hybrid circuit forming the dual-laser source. This source has been previously used for free-running mm-wave generation [3] and optical transmission [13]. Since both lasers in the PIC are identical, only the locking characteristics of laser 1 were measured.…”

“…A microwave photonics application that has been recently explored in this hybrid platform is mm-wave heterodyne generation [3]. Recent works integrating two InP-Si 3 N 4 lasers on the same chip have shown that, while the two lasers can have very low intrinsic linewidth, the RF beatnote still exhibits a long-term drift due to thermal instabilities [3]. This drift can hinder the use of such a solution on any telecom system due to failing to comply with current regulations on frequency stability [4].…”

Control of dual-wavelength laser emission via optical feedback phase tuning

“…Naturally, photonic integrated circuits (PICs) appear to be the ideal option to overcome these issues, especially considering the recent boom of generic foundry platforms [7], [8], [9]. Integrating distinct lasers on the same chip and then merging their beams is a straightforward solution [10], [11], [12], [13], [14] but the absence of coupling between the different wavelengths prevent their use in some applications, such as two-color self-mixing velocimetry for which the mode competition represent a key element [15]. Moreover, the phase noises for each laser are uncorrelated and therefore adds up which can be an important drawback [16].…”

Flexible V-band mmWave Analog-RoF Transmission of 5G and WiGig signals using an InP-SiN Integrated Laser Module

“…In this paper, we demonstrate an optical heterodyne A-RoF system with a dual tunable hybrid integrated InP-SiN laser module and simplified system architecture incorporating a single ended modulator, a single optical amplifier and an envelope detector. Based on the use of integrated micro-ring resonators (MRRs) the dual laser module has been shown to be tunable over the entire C band [10] and can be fine-tuned to achieve desired carrier frequency spacings -offering continuous RF carrier tuning from 5 GHz to 150 GHz when used in a heterodyne configuration [11]. More details of the laser module and system are discussed in section II.…”