Periodic Reporting for period 1 - M-Engine (Microcomb Photonic Engine)
Reporting period: 2023-12-01 to 2024-11-30
M-ENGINE proposes a unique solution to the rapidly increasing bandwidth demands of data centers. With the massive growth of AI and social media in an increasingly connected world, data centers are expected to account for 20% of Europe's energy use by 2030, posing a significant challenge to meet the EU's climate goals. Current solutions to increase bandwidth in optical communications involve adding more single-channel lasers, which neither meets the capacity needs nor the energy requirements. Our proposal offers a scalable solution based on the Nobel prize-winning technology of optical frequency combs to provide highly coherent multi-channel lasers for high-capacity, low energy consumption data transmission. M-ENGINE's solution can replace 100s of individual lasers used in connecting data centers with just one compact system. The proposal combines Enlightra's photonic chip technology with X-Celeprint's cutting-edge solution of micro-transfer printing for scalable heterogeneous integration of all necessary photonic and electronic components. Eblana photonics’ high-power distributed feedback lasers will be transformed for transfer printing on the wafer scale, while Deutsches Elektronen-Synchrotron (DESY) and Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB) will contribute recent breakthroughs in chip-integrated frequency combs enabling increased efficiency, stability, and equalized power of the generated data channels. Dublin City University (DCU) will perform independent performance testing for telecom before test devices are sent out to customers for pilot projects. The result will be a scalable photonic chip engine meeting future data needs with reliability, long-term operation, and a clear business case. M-ENGINE's primary market focus will be data centers, but it will have the flexibility to address related markets, such as photonic computing. The consortium aims to create a viable solution in 5 years when the market is expected to be valued at €14Bn.
Development of photonic architecture of M-ENGINE modules to meet the required KPIs: The M-ENGINE partners have drafted a system architecture based on the evaluation of industrial foundry capabilities and component performance. In particular, the foundry platform provides the photonic basis for the module: the SiN propagation loss dictates the maximum achievable quality factor (Q-factor), and hence, requisite laser pump power for comb generation. The consortium explored various mitigation and compensation strategies for vertical misalignment and also developed an approach enabling evanescent coupling of SOAs for amplification, post-comb generation. Additionally, close collaboration with X-Celeprint during this evaluation and design process enabled the inclusion of MTP design considerations from the outset.
Development of high-power distributed feedback lasers for transfer printing: In year 1 we completed a fabrication run of high-power DFB lasers which involved epitaxial growth, grating write, waveguide etching, and singulation of the lasers based on traditional cleaving techniques with a portion of the wafer reserved for dry etching of the facets to allow a comparison study between both techniques. Etching the facets & wafer level coating is a key step in moving from individual cleaved lasers to wafer-level processing and MTP. Additionally, we have a design in place to include the requisite chip modifications necessary for flip-chip transfer printing, i.e. top side P/N electrical contacts, etched facets, alignment fiducials and inclusion of the release layer in the epi stack to enable MTP of the laser.
Development of full wafer-scale transfer printing: The consortium has developed an epitaxial design which includes X-Celeprint’s release layer, i.e. 500nm AlInAs. The position of the release layer is critical to ensure optimal alignment of the laser mode with the SiN waveguide mode and Enlightra have provided the required thickness for the n-cladding of the InP chip allowing an epitaxial growth run to commence in Q1 2025.
Design of optimized nanostructured photonic microresonator: DESY and ICB reported the initial safe design of the microresonator, including the mask layout for chip- and wafer-level fabrication, following the PDK rules of the fabrication provider LIGENTEC. The design is based on numerical simulations and published experimental results. This base design aims to guarantee minimum performance in frequency comb generation as part of the laser co-integration development aspect of the project, in order to de-risk this stage of technological development.
DESY, with input from M-ENGINE partners, has developed a new design for PhCR structures that includes complex corrugation patterns. The aim of these structures is to test output comb spectrum shaping. ICB has developed ring and PhCR structures for a new 350 nm silicon nitride thickness platform provided by LIGENTEC (AN350).
Testbench development and peformance testing. A testbench has been developed that can characterise the main parameters of the M-Engine devices including basic spectral output, output power per carrier, relative intensity noise (RIN) and phase noise of the comb lines, and phase correlation between the comb lines. Initial testing has been carried out using a benchtop Kerr comb source from Enlightra. A system evaluation testbed has also been developed to operate in the C Band (1530 to 1570nm) with an intensity modulation / direct detection system operating at baud rates upto 100 Gbaud with OOK and PAM4 modulation formats.
Development of high-power distributed feedback lasers for transfer printing: In year 1 we completed a fabrication run of high-power DFB lasers which involved epitaxial growth, grating write, waveguide etching, and singulation of the lasers based on traditional cleaving techniques with a portion of the wafer reserved for dry etching of the facets to allow a comparison study between both techniques. Etching the facets & wafer level coating is a key step in moving from individual cleaved lasers to wafer-level processing and MTP. Additionally, we have a design in place to include the requisite chip modifications necessary for flip-chip transfer printing, i.e. top side P/N electrical contacts, etched facets, alignment fiducials and inclusion of the release layer in the epi stack to enable MTP of the laser.
Development of full wafer-scale transfer printing: The consortium has developed an epitaxial design which includes X-Celeprint’s release layer, i.e. 500nm AlInAs. The position of the release layer is critical to ensure optimal alignment of the laser mode with the SiN waveguide mode and Enlightra have provided the required thickness for the n-cladding of the InP chip allowing an epitaxial growth run to commence in Q1 2025.
Design of optimized nanostructured photonic microresonator: DESY and ICB reported the initial safe design of the microresonator, including the mask layout for chip- and wafer-level fabrication, following the PDK rules of the fabrication provider LIGENTEC. The design is based on numerical simulations and published experimental results. This base design aims to guarantee minimum performance in frequency comb generation as part of the laser co-integration development aspect of the project, in order to de-risk this stage of technological development.
DESY, with input from M-ENGINE partners, has developed a new design for PhCR structures that includes complex corrugation patterns. The aim of these structures is to test output comb spectrum shaping. ICB has developed ring and PhCR structures for a new 350 nm silicon nitride thickness platform provided by LIGENTEC (AN350).
Testbench development and peformance testing. A testbench has been developed that can characterise the main parameters of the M-Engine devices including basic spectral output, output power per carrier, relative intensity noise (RIN) and phase noise of the comb lines, and phase correlation between the comb lines. Initial testing has been carried out using a benchtop Kerr comb source from Enlightra. A system evaluation testbed has also been developed to operate in the C Band (1530 to 1570nm) with an intensity modulation / direct detection system operating at baud rates upto 100 Gbaud with OOK and PAM4 modulation formats.
Key technical results beyond the state of the art have been published in two international open access and peer reviewed journals
“2×53 Gbit/s PAM-4 Transmission Using 1.3 μm DML with High Power Budget Enabled by Quantum-Dot SOA” in IEEE Photonics Technology Letters DOI 10.1109/LPT.2024.3504841 which demonstrates high-capacity, energy-efficient optical data transmission using directly modulated lasers and quantum dot SOAs, reducing loss and energy per bit while enabling long-distance links.
“Simplified Laser Frequency Noise Measurement Using the Delayed Self-Heterodyne Method” in MDPI Photonics Journal, DOI 10.3390/photonics11090813 which reports on a simplified laser frequency noise measurement technique.
“2×53 Gbit/s PAM-4 Transmission Using 1.3 μm DML with High Power Budget Enabled by Quantum-Dot SOA” in IEEE Photonics Technology Letters DOI 10.1109/LPT.2024.3504841 which demonstrates high-capacity, energy-efficient optical data transmission using directly modulated lasers and quantum dot SOAs, reducing loss and energy per bit while enabling long-distance links.
“Simplified Laser Frequency Noise Measurement Using the Delayed Self-Heterodyne Method” in MDPI Photonics Journal, DOI 10.3390/photonics11090813 which reports on a simplified laser frequency noise measurement technique.