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.
