The development of novel mid-infrared (MIR) devices and systems is crucial for addressing applications in biomedical analysis, chemical reaction-monitoring, or high-bitrate free-space telecommunication. Combining multiple functional elements on one chip into complex miniaturized photonic integrated circuits (PICs), is the next step in these developments, yet limited by existing material and technology constraints. In this work, we introduce a new concept for realizing fully monolithic MIR-PICs based on low-loss on-chip plasmonic guiding and beam combining. The core of our study demonstrates a monolithic beam combiner by integration of active quantum cascade (QC) devices at ∼8 µm (laser and detector) with tailored passive waveguides based on weakly-coupled Ge/Au plasmonics and on-chip micro-mirror optics. The on-chip gold-coated micro-mirrors enhance the directional control and beam combining capabilities of the plasmon waveguides while minimizing energy dissipation typically associated with tight plasmon confinement. We discuss the MIR-PIC beam combiner design, micro-fabrication, and characterization and compare it to the routing concept of simple plasmonic Ge/Au y-couplers exploiting strong-confinement.

3 5 Lab A Joint Thales Nokia and CEA LETI laboratory Palaiseau France

CEITEC Brno University of Technology Brno Czech Republic

Current Address Department of Applied Mathematics and Physics University of Applied Sciences Technikum Wien Vienna Austria

Institute of Chemical Technologies and Analytics TU Wien Wien Austria

Institute of Solid State Electronics and Center for Micro and Nanostructures TU Wien Wien Austria

Silicon Austria Labs Villach Austria

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Bardeen J., Brattain W. H. The transistor, A semi-conductor triode. Phys. Rev. . 1948;74(2):230. doi: 10.1103/physrev.74.230. DOI

. 2023. https://www.apple.com/newsroom/2023/06/apple-introduces-m2-ultra/

Masharin M. A., et al. Polariton lasing in Mie-resonant perovskite nanocavity. Opto-Electron Adv. . 2024;7(4):230148. doi: 10.29026/oea.2024.230148. DOI

Asghari M., Krishnamoorthy A. V. Energy-efficient communication. Nat. Photonics . 2011;5(5):268. doi: 10.1038/nphoton.2011.68. DOI

Testa F., Bianchi A., Stracca S., Sabella R. Silicon Photonics III – Systems and Applications . Berlin: Springer Nature; 2016. pp. 421–446.

Tuorila H., Viheriälä J., Cherchi M., Aho A. T., Aalto T., Guina M. Low loss GaInNAs/GaAs gain waveguides with U-bend geometry for single-facet coupling in hybrid photonic integration. Appl. Phys. Lett. . 2018;113(4):20240688. doi: 10.1063/1.5042813. DOI

Zhou Z., et al. Prospects and applications of on-chip lasers. eLight . 2023;3(1):20240688. doi: 10.1186/s43593-022-00027-x. PubMed DOI PMC

Thiel H., et al. Time-bin entanglement at telecom wavelengths from a hybrid photonic integrated circuit. Sci. Rep. . 2024;14 doi: 10.1038/s41598-024-60758-4. PubMed DOI PMC

Fabian H., Mäntele W. In Book: Handbook of Vibrational Spectroscopy . Hoboken, NJ: Wiley; 2006.

Hinkov B., et al. Time-resolved spectral characteristics of external-cavity quantum cascade lasers and their application to stand-off detection of explosives. Appl. Phys. B Laser Opt. . 2010;100:253. doi: 10.1007/s00340-009-3863-7. DOI

Tuzson B., Mangold M., Looser H., Manninen A., Emmenegger L. Compact multipass optical cell for laser spectroscopy. Opt. Lett. . 2013;38(3):257. doi: 10.1364/ol.38.000257. PubMed DOI

Patimisco P., Scamarcio G., Tittel F. K., Spagnolo V. Quartz-enhanced photoacoustic spectroscopy: a review. Sensors (Peterb., NH) . 2014;14(4):6165. doi: 10.3390/s140406165. PubMed DOI PMC

Schädle T., Mizaikoff B. Mid-infrared waveguides: a perspective. Appl. Spectrosc. . 2016;70(10):1625. doi: 10.1177/0003702816659668. PubMed DOI

Karioja P., et al. Multi-wavelength mid-IR light source for gas sensing. SPIE. 2017;10110:101100P. doi: 10.1117/12.2249126. DOI

Schwaighofer A., Lendl B. Vibrational Spectroscopy in Protein Research . Cambridge, MA: Academic Press; 2020. pp. 59–88.

Vlk M., et al. Extraordinary evanescent field confinement waveguide sensor for mid-infrared trace gas spectroscopy. Light: Science & Applications . 2021;10:26. doi: 10.1038/s41377-021-00470-4. PubMed DOI PMC

Nie Q., et al. Agile cavity ringdown spectroscopy enabled by moderate optical feedback to a quantum cascade laser. Opto-Electron Adv. . 2024;7(11):240077. doi: 10.29026/oea.2024.240077. DOI

Corrias N., Gabbrielli T., Natale P. D., Consolino L., Cappelli F. Opt. Express . 2022;30(7):10217. PubMed

Didier P., et al. High-capacity free-space optical link in the midinfrared thermal atmospheric windows using unipolar quantum devices. Adv. Photonics . 2022;4(5):20240688. doi: 10.1117/1.ap.4.5.056004. DOI

Dely H., et al. High bitrate data transmission in the 8-14 µm atmospheric window using an external Stark-effect modulator with digital equalization. Opt. Express . 2023;31(5):7259. doi: 10.1364/oe.474209. PubMed DOI

Hinkov B., et al. A mid-infrared lab-on-a-chip for dynamic reaction monitoring. Nat. Commun. . 2022;13:4753. doi: 10.1038/s41467-022-32417-7. PubMed DOI PMC

Pilat F., et al. Beyond Karl Fischer titration: A monolithic quantum cascade sensor for monitoring residual water concentration in solvents. Lab Chip . 2023;23:1816. doi: 10.1039/d2lc00724j. PubMed DOI PMC

Graydon O. Quantum cascade laser turns thirty. Nat. Photon. . 2025;19:132–133. doi: 10.1038/s41566-025-01623-2. DOI

Schwarz B., et al. Watt-level continuous-wave emission from a bifunctional quantum cascade laser/detector. ACS Photonics . 2017;4(5):1225. doi: 10.1021/acsphotonics.7b00133. PubMed DOI PMC

Lu Q., Bai Y., Bandyopadhyay N., Slivken S., Razeghi M. 2.4 W room temperature continuous wave operation of distributed feedback quantum cascade lasers. Appl. Phys. Lett. . 2011;98:18. doi: 10.1063/1.3588412. DOI

Hinkov B., Bismuto A., Bonetti Y., Beck M., Blaser S., Faist J. Singlemode quantum cascade lasers with power dissipation below 1 W. Electron. Lett. . 2012;48(11):646. doi: 10.1049/el.2012.1204. DOI

Marschick G., et al. High-responsivity operation of quantum cascade detectors at 9 µm. Opt. Express . 2022;30(22):40188. doi: 10.1364/oe.470615. PubMed DOI

Delga A. Mid-infrared Optoelectronics . Cambridge: Woodhead Publishing; 2020. pp. 337–377.

Hinkov B., Fuchs F., Bronner W., Köhler K., Wagner J. Current- and temperature-induced beam steering in 7.8-µm emitting quantum-cascade lasers. IEEE J. Quant. Electron. . 2008;44(11):1124. doi: 10.1109/jqe.2008.2003499. DOI

Heck M. J. Highly integrated optical phased arrays: Photonic integrated circuits for optical beam shaping and beam steering. Nanophotonics . 2017;6(1):93. doi: 10.1515/nanoph-2015-0152. DOI

Guo W., et al. Two-dimensional optical beam steering with InP-based photonic integrated circuits. IEEE J. Sel. Top. Quant. Electron. . 2013;19(4):6100212. doi: 10.1109/jstqe.2013.2238218. DOI

Jung S., et al. Homogeneous photonic integration of mid-infrared quantum cascade lasers with low-loss passive waveguides on an InP platform. Optica . 2019;6(8):1023. doi: 10.1364/optica.6.001023. DOI

Wang R., Täschler P., Wang Z., Gini E., Beck M., Faist J. Monolithic integration of mid-infrared quantum cascade lasers and frequency combs with passive waveguides. ACS Photonics . 2022;9(2):426–431. doi: 10.1021/acsphotonics.1c01767. DOI

Burghart D., et al. Multi-color photonic integrated circuits based on homogeneous integration of quantum cascade lasers. Nat. Commun. . 2025;16:3563. doi: 10.1038/s41467-025-58905-0. PubMed DOI PMC

Zafar H., Pereira M. F. An efficient and compact mid-infrared polarization splitter and rotator based on a bifurcated tapered-bent waveguide. Sci. Rep. . 2025;15:5160. doi: 10.1038/s41598-025-89420-3. PubMed DOI PMC

Chatzianagnostou E., et al. Scaling the sensitivity of integrated plasmo-photonic interferometric sensors. ACS Photonics . 2019;6(7):1664. doi: 10.1021/acsphotonics.8b01683. DOI

Homola J. Surface plasmon resonance sensors for detection of chemical and biological species. Chem. Rev. . 2008;108(2):462. doi: 10.1021/cr068107d. PubMed DOI

Slavík R., Homola J. Ultrahigh resolution long range surface plasmon-based sensor. Sens. Actuators B: Chem. . 2007;123(1):10. doi: 10.1016/j.snb.2006.08.020. DOI

Schwarz B., et al. Monolithically integrated mid-infrared lab-on-a-chip using plasmonics and quantum cascade structures. Nat. Commun. . 2014;5:4085. doi: 10.1038/ncomms5085. PubMed DOI PMC

David M., et al. Octave-spanning low-loss mid-IR waveguides based on semiconductor-loaded plasmonics. Opt. Express . 2021;29(26):43567. doi: 10.1364/oe.443966. DOI

David M., et al. Advanced mid-infrared plasmonic waveguides for on-chip integrated photonics. Photonics Res. . 2023;11(10):1694. doi: 10.1364/prj.495729. DOI

Krasavin A., Zayats A. Passive photonic elements based on dielectric-loaded surface plasmon polariton waveguides. Appl. Phys. Lett. . 2007;90:21. doi: 10.1063/1.2740485. DOI

Zhong Y., Malagari S. D., Hamilton T., Wasserman D. Review of mid-infrared plasmonic materials. J. Nanophotonics . 2015;9(1):093791. doi: 10.1117/1.jnp.9.093791. DOI

Schädle T., Mizaikoff B. Mid-infrared waveguides: a perspective. Appl. Spectrosc. . 2016;70(10):1625. doi: 10.1177/0003702816659668. PubMed DOI

David M., et al. Structure and mid-infrared optical properties of spin-coated polyethylene films developed for integrated photonics applications. Opt. Mater. Express . 2022;12(6):2168. doi: 10.1364/ome.458667. DOI

Hinkov B., David M., Strasser G., Schwarz B., Lendl B. On-chip liquid sensing using mid-IR plasmonics. Front. Photonics . 2023;4:1213434. doi: 10.3389/fphot.2023.1213434. DOI

Cin S. D., et al. An interband cascade laser based heterodyne detector with integrated optical amplifier and local oscillator. Nanophotonics . 2024;13(10):1759. doi: 10.1515/nanoph-2023-0762. PubMed DOI PMC

David M., et al. Surface protection and activation of mid-IR plasmonic waveguides for spectroscopy of liquids. J. Lightwave Technol. . 2023 doi: 10.1109/jlt.2023.3321034. in press . DOI

Gsodam X. . Technische Universität Wien; 2023. Mid-infrared plasmonic waveguide design and characterization for a chip-scale heterodyne receiver. Diploma Thesis.

David M. Plasmonics for mid-infrared photonic integrated circuits. Technische Universität Wien; 2023. Dissertation.

Markey L., Vernoux C., Hammani K., Arocas J., Weeber J.-C., Dereux A. A long-range plasmonic optical waveguide corner mirror chip. Micro Nano Eng. . 2020;7:100049. doi: 10.1016/j.mne.2020.100049. DOI

Berini P., Charbonneau R., Lahoud N., Mattiussi G. Characterization of long-range surface-plasmon-polariton waveguides. J. Appl. Phys. . 2005;98:4. doi: 10.1063/1.2008385. PubMed DOI

Orieux A., Diamanti E. Recent advances on integrated quantum communications. J. Opt. . 2016;18(8):20240688. doi: 10.1088/2040-8978/18/8/083002. DOI

Chen C., Wang J. Optical biosensors: An exhaustive and comprehensive review. Analyst . 2020;145:1605. doi: 10.1039/c9an01998g. PubMed DOI