Periodic Reporting for period 2 - OPHELLIA (On-chip PHotonics Erbium-doped Laser for LIdar Applications)
Periodo di rendicontazione: 2022-07-01 al 2023-12-31
High performance lightweight laser scanners would permit the widespread use of professional LiDAR tools in complex environments like industry, archaeology and traffic or the integration of ground based robotic systems in human work environment. Miniaturized, yet nevertheless highly sensitive and fast LiDAR systems also serve market demands for easier system integration on small drones for challenging small-scale flight missions, for instance to monitor construction works, traffic observation, instable topography, or to assist rescue work in emergency scenarios. These applications typically use pulsed lasers in time of flight (TOF) LiDARs. Trains, airplanes in airports, big cranes in harbors, for example, are increasingly autonomous. Their movement needs to be safe for both the objects to be moved (i.e. detection of obstacles on their paths), but also for the people surrounding the objects, such as harbor, airport or railway workers and passengers. To this aim, reliable real-time measurement of distances (range) between objects and between objects and persons under all circumstances (i.e. fog, rain, snow, day, night), as well as their relative velocity is mandatory. These applications typically use frequency modulated lasers in FMCW LiDARs.
Unfortunately there are very few laser light sources available that could provide sufficient performance to achieve the required distance range, distance resolution, and velocity accuracy. Moreover, the available sources, namely single mode or multimode laser diodes and fiber laser sources, are either very costly, not sufficiently robust, or not compact enough for the applications.
The Integrated Photonics Systems Roadmap (IPSR) has identified integrated photonics as a key enabling technology for LiDAR, allowing to achieve simultaneously high performance (in terms of range, distance, and velocity resolution), and low cost. Photonic integrated circuits (PICs) - devices that integrate many optical functionalities on a single chip including light emission, routing, modulation and detection - have been recognized to play a crucial role in coming years to push LiDAR systems towards mass market applications.
The objective of OPHELLIA is to develop novel materials and integration technology for the realization of innovative PIC building blocks to develop PIC based laser sources for emerging TOF and FMCW LiDAR applications exhibiting low cost and low size thanks to the high chip integration and tolerant packaging technology while, at the same time, exhibiting the same or even higher performance than existing solutions.
Unfortunately there are very few laser light sources available that could provide sufficient performance to achieve the required distance range, distance resolution, and velocity accuracy. Moreover, the available sources, namely single mode or multimode laser diodes and fiber laser sources, are either very costly, not sufficiently robust, or not compact enough for the applications.
The Integrated Photonics Systems Roadmap (IPSR) has identified integrated photonics as a key enabling technology for LiDAR, allowing to achieve simultaneously high performance (in terms of range, distance, and velocity resolution), and low cost. Photonic integrated circuits (PICs) - devices that integrate many optical functionalities on a single chip including light emission, routing, modulation and detection - have been recognized to play a crucial role in coming years to push LiDAR systems towards mass market applications.
The objective of OPHELLIA is to develop novel materials and integration technology for the realization of innovative PIC building blocks to develop PIC based laser sources for emerging TOF and FMCW LiDAR applications exhibiting low cost and low size thanks to the high chip integration and tolerant packaging technology while, at the same time, exhibiting the same or even higher performance than existing solutions.
M1-18
During the first reporting period, the system level requirements were flown down to the component level and the performance parameters for each of the photonic building blocks were determined. The design of the basic building blocks has been completed. Both the passive building blocks as well as the on-chip amplifiers are currently under fabrication and will be characterized in the next reporting period. In order to achieve the targeted resolution requirements for the FMCW source, a gain section length of less than 3 cm is required, which, together with the requirement of >100 mW of laser power, poses severe restrictions into the gain material. On chip waveguide amplifiers pumped at 1480 nm are being currently optimized.
Efficient coupling in and out the photonic chips is key for the performance of the final prototype. OPHELLIA has designed in- and out-coupling 3D printed microlenses to both increase the coupling efficiency and increase the alignment tolerance of the system.
A pulsed laser deposition (PLD) process for the deposition of the magneto-optical material, Bi:YIG, has been developed. A field rotation performance of 4.5 deg/µm has been reached after the optimization of the Bi:YIG growth conditions. In the next step, the material will be integrated onto Si3N4 waveguides to produce on-chip optical isolators.
Finally, a data management plan, exploitation and dissemination plan, internal training plan and a web survey have all been completed and are in execution.
M19-29
Attendance at many conferences (i.e. invited talks at OFC 2023 and CLEO US 2023 and oral presentations at Photonics West 2024)
Submission of journal paper in Optics Express with world record result (i.e. over 30 dB of small signal internal gain).
Various runs of Si3N4 have resulted in samples being fabricated for amplifiers and laser cavities to be distributed to the partners for 3D-printed freeform lenses, laser characterization, and packaging.
OPHELLIA has suggested some alterations to the KPIs and is acting on some mitigations. Mainly, this results in the abandonment of on-chip isolators and booster amplifiers fully integrated on the same PIC and instead continue their individual development as PIC building blocks
An additional six months has been suggested without additional funding in order to allow the end users more time to test the deliverable devices due to the overall delay in the project
M30-36
Acceptance of a journal paper (Optics Express)
Fabricated amplifiers and lasers on Si3N4 were characterized by WP3 partners
Passive devices such as on-chip WDMs and laser cavity components were off specification and limited the overall performance of the devices intended for packaging.
Very long (20 cm) amplifier waveguides, not intended for packaging, were measured at the UT showing exceptional performance, including the demonstration of external fiber-fiber gain for the first time (7dB) and 50 mW of on-chip power.
Implementation of the microlenses on chips intended for packaging with the Fabry Perot pumps was carried out by Vanguard.
Keopsys successfully completed a packaged chip to demonstrate that the process can couple two Fabry Perot pumps to the chip with 60 % coupling efficiency.
WP2 requires 6 months of funding-free run time be allocated such that there is sufficient time for characterization.
Additional fabriction RUN suggested to account for the off specification Si3N4 passive components.
During the first reporting period, the system level requirements were flown down to the component level and the performance parameters for each of the photonic building blocks were determined. The design of the basic building blocks has been completed. Both the passive building blocks as well as the on-chip amplifiers are currently under fabrication and will be characterized in the next reporting period. In order to achieve the targeted resolution requirements for the FMCW source, a gain section length of less than 3 cm is required, which, together with the requirement of >100 mW of laser power, poses severe restrictions into the gain material. On chip waveguide amplifiers pumped at 1480 nm are being currently optimized.
Efficient coupling in and out the photonic chips is key for the performance of the final prototype. OPHELLIA has designed in- and out-coupling 3D printed microlenses to both increase the coupling efficiency and increase the alignment tolerance of the system.
A pulsed laser deposition (PLD) process for the deposition of the magneto-optical material, Bi:YIG, has been developed. A field rotation performance of 4.5 deg/µm has been reached after the optimization of the Bi:YIG growth conditions. In the next step, the material will be integrated onto Si3N4 waveguides to produce on-chip optical isolators.
Finally, a data management plan, exploitation and dissemination plan, internal training plan and a web survey have all been completed and are in execution.
M19-29
Attendance at many conferences (i.e. invited talks at OFC 2023 and CLEO US 2023 and oral presentations at Photonics West 2024)
Submission of journal paper in Optics Express with world record result (i.e. over 30 dB of small signal internal gain).
Various runs of Si3N4 have resulted in samples being fabricated for amplifiers and laser cavities to be distributed to the partners for 3D-printed freeform lenses, laser characterization, and packaging.
OPHELLIA has suggested some alterations to the KPIs and is acting on some mitigations. Mainly, this results in the abandonment of on-chip isolators and booster amplifiers fully integrated on the same PIC and instead continue their individual development as PIC building blocks
An additional six months has been suggested without additional funding in order to allow the end users more time to test the deliverable devices due to the overall delay in the project
M30-36
Acceptance of a journal paper (Optics Express)
Fabricated amplifiers and lasers on Si3N4 were characterized by WP3 partners
Passive devices such as on-chip WDMs and laser cavity components were off specification and limited the overall performance of the devices intended for packaging.
Very long (20 cm) amplifier waveguides, not intended for packaging, were measured at the UT showing exceptional performance, including the demonstration of external fiber-fiber gain for the first time (7dB) and 50 mW of on-chip power.
Implementation of the microlenses on chips intended for packaging with the Fabry Perot pumps was carried out by Vanguard.
Keopsys successfully completed a packaged chip to demonstrate that the process can couple two Fabry Perot pumps to the chip with 60 % coupling efficiency.
WP2 requires 6 months of funding-free run time be allocated such that there is sufficient time for characterization.
Additional fabriction RUN suggested to account for the off specification Si3N4 passive components.
On-chip optical amplifiers and isolators are key components in many photonic integrated circuits. The high gain per unit length and high output power on-chip amplifiers developed in OPHELLIA will not only benefit the development of the FMCW and TOF sources but many other applications, as identified by partner Tematys. Based on interviews with various key players in the fields of PICs and LiDARs, we have shortlisted the following applications:
1. Integrated 515nm laser Source for Quantum-Magneto-encephalography
2. Integrated 515nm laser source for submarine FSO
3. Integrated laser source for Wind mapping (C-Band)
4. Integrated laser source for Comb-based gas sensor
5. Atomic clocks
Among all these applications, Quantum-Magneto-Encephalography has a potential of 100,000s of units and is driven by key European players like Bosch, Thales, etc.
1. Integrated 515nm laser Source for Quantum-Magneto-encephalography
2. Integrated 515nm laser source for submarine FSO
3. Integrated laser source for Wind mapping (C-Band)
4. Integrated laser source for Comb-based gas sensor
5. Atomic clocks
Among all these applications, Quantum-Magneto-Encephalography has a potential of 100,000s of units and is driven by key European players like Bosch, Thales, etc.