INdium PHOsphide-based advanced Monolithically integrated photonic building-blocks at near and mid-InfraRed wavelengths

Project Information

INPHOMIR

Grant agreement ID: 101135749

DOI

10.3030/101135749

EC signature date 28 November 2023

Start date 1 December 2023

End date 30 November 2027

Funded under

• Digital, Industry and Space

Total cost

€ 4 999 637,50

EU contribution

€ 4 999 637,50

Coordinated by

G.E.M. ELETTRONICA SRL
Italy

Periodic Reporting for period 1 - INPHOMIR (INdium PHOsphide-based advanced Monolithically integrated photonic building-blocks at near and mid-InfraRed wavelengths)

Reporting period: 2023-12-01 to 2025-05-31

Summary of the context and overall objectives of the project

Monitoring the dynamics of a nanosatellite in space or of an autonomous driving unit on earth, tracking a moving object into a noisy environment or performing advanced spectroscopy through the atmosphere are just few practical examples of cutting-edge applications that could highly benefit of integrated photonics implementation. The INPHOMIR project is motivated by the drive to develop complex photonic integrated control-units and devices enabling innovative EU technologies in the domains of inertial navigation and mid-infrared remote sensing. Several apparatuses of these high-tech subject areas are indeed limited by the lack of components characterized by low Size-Weight-and-Power-consumption (SWaP) factors. Regarding high-performance optoelectronic devices, typically complex heterogeneous circuits are needed to satisfy and implement specific architectures.
The adoption of photonic integrated circuits (PICs) for these applications has been restrained by the difficulty of integrating both active and passive components on the same chip: while heterogeneous silicon photonics is affected by low-reliability processes, the Indium Phosphide monolithic platform is seen as the valid solution for a technological scale-up. INPHOMIR’s activity focuses on the development of advanced PIC modules which monolithically integrate the active and passive building blocks, by exploring innovative design concepts and epitaxial material systems, for miniaturization, manufacturability and performance.

In particular, the project targets the two following objectives:
- the realization of advanced monolithic PIC functionalities based on innovative concepts like on-chip optical compensation, slow-light-induced extremely-high quality-factor, Hertz-level laser stabilization and ultralow- power dual-band coherent detection. This novel generation of PICs will promote a completely European InP-based process design kit and supply chain, validating wafer-scale processes and promoting EU independence in photonic technologies
- experimental implementations of complex modular photonic integrated circuits at near and mid-infrared wavelengths to validate a photonic-enable multi-sensor module for autonomous and space navigation, enabling a sensor-fusion-technology to be employed in high-tech SME and industrial R&D departments

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Objective 1: Validation of a competitive broadband InP-based photonic platform across near- and midinfrared wavelengths: study, design and manufacturing of basic monolithic building-blocks to implement high-performance passive and active PICs such as low-loss-waveguides, lasers, detectors, modulators.

- Advancements on NIR photonic platform and corresponding building blocks:
New components that are needed for integrated gyroscopes and that are not available in the standard toolkit from the foundries (e.g. SMART Photonics) or from the internal TU/e building block libraries were designed and the fabrication run of low-loss passive components and circuits was started. Laser designs with low linewidths were fabricated and measured. Design of photonic circuits with combination of building blocks were evaluated for functionality and packaging requirements. These designs have been converted to layout and a fabrication run based on these circuits is ongoing.
- Advancements on MIR photonic platform and corresponding building blocks:
Low-loss passive waveguides based on InGaAs/InP materials were obtained through MOVPE growth optimization. Background carrier concentration below 10e14 cm-3 were obtained in all waveguide layers, allowing for a significant reduction in waveguide losses for TM-polarized light with respect to previously reported results, particularly at LWIR wavelengths. Heterostructures designs for QCLs and QCDs operating in the MWIR and LWIR bands were developed, and the corresponding band structures computed. The designed heterostructures were grown by molecular beam epitaxy (MBE) and ridge-waveguide lasers or detectors were processed and tested. High detector responsivity as well as laser operation at the target wavelengths were demonstrated for both operating wavelengths.

Objective 2: Demonstration of innovative PIC functionalities based on InP-monolithic integration such as on-chip optical loss compensation on spiral-resonators (OC-SR), ring resonators coupled to photonic crystal cavities (PhC-RR), QCL spectral stabilization (QCL-RR) and balanced on-chip photodetection (BH-QCD).

- A fully integrated passive spiral resonator including a semiconductor optical amplifier (SOA) in a section of the path was designed. Trial runs are planned to test optically compensated spiral designs with single and distributed amplifiers.
- A photonic crystal ring resonator was designed for optimized performance for integration into a monolithically integrated optical gyroscope. The waveguide design was refined to determine the regime of single-mode operation, and the impact of waveguide curvature on the resonator’s performance was assessed. Grating period and etch depth were optimized, along with the coupling gap for the best trade-off between Q-factor enhancing and extinction ratio reduction.
- Several designs of single-band narrow-linewidth emitting QCLs were evaluated through simulation for implementation in INPHOMIR within the In-P based platform. Narrow-linewidth mid-infrared QCL PICs were fabricated, consisting of a symmetric add-drop ring resonator followed by a reflector at the end of the drop port to ensure feedback to the laser gain section. Variations of critical parameters controlling ring-waveguide power coupling were tested. Characterization activities of the fabricated PICs are ongoing.
- Balanced heterodyne detection PIC were designed, consisting of a reference DFB QCL and an input waveguide, coupling light to two balanced QCDs. Variations of such design were assessed. First BHD PICs were fabricated at TUM, exploring such different configurations. Characterization activities of the fabricated PICs are ongoing.

Objective 3: Validation of advanced on-chip sensors such as an integrated optical gyroscope and a midinfrared on-chip FMCW lidar with advanced assembly of read-out electronics, multiple-chip-module packaging and development of software control for the multi-sensing device.

- Design activities of the advanced integrated optical gyroscopes and a midinfrared FMCW lidar PICs are ongoing: The fabrication of first NIR PIC integrating active and passive building blocks on TU/e’s low-loss platform is planned for the second half of 2025. Fabrication of PICs on a higher-loss platform are ongoing for providing first test structures for packaging activities, electronics design and testing setups.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

First results and potential impacts of the ongoing research work will be discussed once the development of advanced functions PICs is ultimated and characterization results are available.