Photonics - INPhO
Integrated Nanoscale Photonics and Optoelectronics Laboratory (INPhO) at EPFL
The INPhO Laboratory at EPFL is led by Kirsten Moselund and was established in 2022 when she moved from IBM to academia. She currently holds a double affiliation with PSI as head of LNQ and as professor of electronics and microtechnology at EPFL, it is part of the faculty of Engineering and Technology (STI). The activities are currently spread between the PSI in Villigen - Aargau, EPFL in Lausanne – Vaud and the campus of IBM Research Europe – Zurich in Rüschlikon Zürich. However, in the long run it is the goal that the main research activities will be collected at PSI while PhD students are enrolled in the doctoral programs of EPFL.
The work in INPHO has a strong focus on semiconductor technology development and developing novel device architectures for electronics and photonic components. In addition, we enjoy exploring different characterization techniques to get a better understanding of the device physics. To this end, we collaborate with a number of excellent researchers internationally.
Some examples of research projects which were carried out at IBM Research Europe Zurich are shown below. New projects are being shaped at PSI along the same themes.
1. Demonstration of monolithically integrated III-V nanophotonic devices on silicon
For on-chip applications, we desire small active components for three reasons: integration density, higher speed because of smaller round-trip times in the cavity and smaller capacitances, and thirdly because smaller lasers can have smaller threshold currents and thus operates at lesser power.
At IBM Research, we pioneered Template-Assisted Selective Epitaxy (TASE). A novel epitaxy approach for the dense on-chip integration of III-V nanostructures. The focus of the ERC StG PLASMIC was on the development of plasmonically-enhanced hybrid nanolasers, fabricated using the TASE III-V integration approach. We have demonstrated monolithically integrated optically pumped GaAs , InP  and InGaAs micro-cavity lasers operating at room temperature as well as hybrid III-V/SI photonic crystal emitters operating over the entire telecom band . We have also demonstrated the first monolithically integrated waveguide coupled InGaAs photodetectors on a SOI photonics platform operating at 50 Gbps OOK as well as light emission from scaled LEDs [2,3].
Presently we are working on expanding this using topological designs and exploiting distributed gain/loss structures as the TASE method allows for local precise placement of optical gain material
Main recent publications:
1. P. Wen, P. Tiwari, S. Mauthe, H. Schmid, M. Sousa, M. Scherrer, M. Baumann, B.Bitachon, J. Leuthold, B. Gotsmann, K. E Moselund, ”Waveguide coupled III-V photodiodes monolithically integrated on Si”, Nature Communications volume 13, no. 909 (2022)
2. S. Mauthe, Y. Baumgartner, M. Sousa, Q. Ding, M. D. Rossell, A. Schenk, L. Czornomaz and K.E Moselund, “High-speed III-V nanowire photodetector monolithically integrated on Si”, Nature Communications 11 (1), 1-7, (2020)
3. S. Mauthe, P. Tiwari, M. Scherrer, D. Caimi, M. Sousa, H. Schmid, K. E. Moselund and N. Vico Triviño, “Hybrid III–V Silicon Photonic Crystal Cavity Emitting at Telecom Wavelengths”, Nano Letters 20 (12), 8768-8772 (2020)
4. S. Mauthe, N. V. Trivino, Y. Baumgartner, M. Sousa, D. Caimi, T. Stoeferle, H. Schmid and K. E. Moselund, "InP-on-Si Optically Pumped Microdisk Lasers via Monolithic Growth and Wafer Bonding," IEEE Journal of Selected Topics in Quantum Electronics, vol. 25, no. 6, p. 8300507, (2019)
5. S. Wirths, B. Mayer, H. Schmid, M. Souza, J. Gooth, H. Riel and K. Moselund, “Room Temperature Lasing from Monolithically Integrated GaAs Microdisks on Si”, ACS Nano, ACS Nano, 12, pp. 2169-2175. (2018)
2. Hybrid plasmonic cavities and the understanding of thermal effects in nanoresonators
One of our goals was specifically to explore the use of metals in combination with scaled laser cavities. In this work, we explored the use of metal-cladding (Au) on InP micro-disc lasers. We found that metal-clad cavities show lasing down to smaller dimensions (~300nm) and more stable lasing at higher powers compared to purely dielectric cavities. Not surprisingly, the use of metals did increase the lasing threshold slightly for room-temperature operated devices . It is difficult to establish experimentally whether a given lasing mode is a hybrid photonic-plasmonic or a conventional photonic mode. However, what we did establish is that the use of a metal cavity dramatically improves the heat-sinking capability and hence reduces the temperatures reached in the nanolasers with hundreds of degrees during operation compared to purely dielectric cavities. In a follow-up work this was verified experimentally by the use of calibrated Raman measurements .
Recently we investigated the use of Au nano-antennae coupled to InP microdisk lasers . The optimized placement of an Au nano-antenna led to significant side-mode suppression, whereby single-mode lasing could be established. It also improved the temperature stability of the lasing wavelength compared to samples without the nano-antenna.
Main recent publications:
6. P. Tiwari, A. Fischer, M. Scherrer, D. Caimi, H. Schmid, and K. E. Moselund, “Single-Mode Emission in InP Microdisks on Si Using Au Antenna”, ACS Photonics 9 (4), 1218-1225(2022)
7. P. Wen, P.Tiwari, M. Scherrer, E. Lörtscher, B. Gotsmann, and K. E. Moselund, “Thermal Simulation and Experimental Analysis of Optically Pumped InP-on-Si Micro- and Nanocavity Lasers”, ACS Photonics 9 (4), 1338-1348 (2022)
8. P. Tiwari, P. Wen, D. Caimi, S. Mauthe, N.Vico Triviño, M. Sousa, and K. E. Moselund, "Scaling of metal-clad InP nanodisk lasers: optical performance and thermal effects," Opt. Express 29, 3915 (2021)