EXCAR - Sustainable Optical Communication and Sensor Systems based on Extended-Cavity Resonators


The objective of this project is to advance the state-of-the-art in optical access networks and also apply the same ideas to sensor networks. Proposed project addresses the EU targets as defined by European Commission’s “Europe 2020” strategy for smart growth by focusing on research and development of highly-integrated and energy efficient optical transceivers and wavelength-division-multiplexing (WDM) components for next-generation of access and mobile backhaul networks using passive optical network (PON) infrastructure. The primary challenge, in wider adoption of WDM-PON, lies in the development of sufficiently low cost technology to be used at the users’ premises. Self-seeded WDM-PON has been actively investigated in recent years as potentially the lowest cost solution for next-generation access networks. The primary attraction of this architecture is its simplicity, lower power consumption, and cost advantage. Similar principles can be applied to multiplexing and interrogation systems for optical sensors and our aim is to develop, analyze and demonstrate sustainable all-optical infrastructure based on extended cavity resonators able to provide physical layer for both, access communication and sensor networks.

At University of Zagreb we invented an optical component, the modulation-averaging reflector, which reduces the penalty due to modulation of the seeding light and depolarizes the light oscillating in the cavity thereby stabilizing the extended resonator. This was the first step towards a future-proof optical access technology. Within this project we will fully develop and characterize systems based on extended cavity resonators with modulation averaging reflectors. We will also explore the use of modulation averaging concept in a novel communication optical source architecture based on wavelength re-use. Finally, the concept of extended cavity resonators will also be implemented in non-communication applications such as new optical sensor schemes. By completing this four-year project, we expect to make fundamental contribution to the science of lasers and fiber-optic components technology by demonstrating the operation and optimization of extended resonators based systems for communications and sensing.


  • Principal Investigator (PI): Professor Zvonimir Šipuš, Ph.D.
  • Host institution: University of Zagreb, Faculty of Electrical Engineering and Computing
  • Project duration: 48 months


Project Team:

The research team consists of two full professors, Zvonimir Šipuš and Borivoj Modlic, two assistant professors Dubravko Babić and Marko Bosiljevac, three PostDocs Josip LončarDario Bojanjac and Damir Muha, and one PhD student Marko Šprem.




  • Šprem, Marko; Babić, Dubravko. 2017. "Wavelength tuning of Fabry-Perot lasers in spectrum-sliced optical links" US patent No. 9, 692, 517 B1 [PDF]
  • Komljenović, Tin; Babić, Dubravko; Šipuš, Zvonimir. 2017. "Optical-coupler based modulation-averaging structures for self-seeded colorless WDM-PON" US patent No. 9, 667, 026 B2 [PDF]
  • Šprem, Marko; Babić, Dubravko. 2017. "Tunable transceivers for colorless spectrum-sliced WDM passive optical networks" US patent No. 9, 628, 175 B2 [PDF]
  • Babić, Dubravko; Komljenović, Tin; Šipuš, Zvonimir. 2017. "Wavelength-reuse fiber-optic transmitters" US patent No. 9, 614, 622 B2 [PDF]
  • Bosiljevac, Marko; Babić, Dubravko. 2017. "Light sources with highly stable output intensity" US patent No. 9, 605, 999 B2 [PDF]