Objectives: This research project will develop a photonic integrated THz frequency domain spectrometer THz FDS, using the self-heterodyne technique based on an optical heterodyne source. This research work will contribute to answering TERAOPTICS’ research Challenge III and Challenge V. Expected Results: The key expected outcome of this research work is a Terahertz frequency domain spectrometer light engine prototype. The aim is to demonstrate the superior performance of the photonic integrated self-heterodyne technique, since influence of frequency fluctuations of the RF signal are eliminated by using the same LO in Tx and Rx, and phase uncertainties are eliminated by integration. Frequency tuning between 30 GHz to 3 THz will be achieved by changing wavelength difference, and phase scanning over 180º using a phase shifter. The research and development work will mainly address the targeted key THz application “material characterization”. Planned secondment(s): to FTMC (Dr. Irmantas Kašalynas), M10 ~1 month, on introduction to solid state THz sources and spectroscopic THz imaging to DAS (Dr. Valentin Polo), M30 for 2 months, on using the prototypes for spectroscopic THz imagers

Objectives: This key objective of this research project is to study and develop photonic integrated mode locked lasers as optical signal sources for frequency-stable and low-phase noise Terahertz signal generation for pumping SBD mixers. Expected Results: The vision of this research work is to develop a high repetition rate mode locked laser diode (MLLD) prototype using intra-cavity and extra-cavity structures that will provide a sub-harmonic continuous wave optical local oscillator signal required to generate high quality frequency stable and low phase noise THz signals. This research work will contribute to answering TERAOPTICS’ research Challenge I, III and V. Planned secondment(s): to UDE (Prof. Andreas Stöhr), M14 for 1 months for round-robin tests of optically-mediated THz signal generation to ULIL (Prof. Guillaume Ducournau), M20 for 1.5 months, to find assembly solutions for THz sources based on mode locked laser to ACST (Dr. Oleg Cojocari), M28 for 1.5 months, to explore assembly of MLLD, high speed PDs for photonic LO signal for SBD receiver

Yılmaz Uçar received his bachelor’s degree in Electronics and Communications Engineering from Doğuş University, Turkey, and his master’s degree in Telecommunications Engineering from Universitat Politècnica de Catalunya (UPC-BarcelonaTech), Spain, with the specialization in Antennas, Microwaves and Photonics for Communications and Earth Observation. His master’s thesis was about designing and testing of microwave circuits for optimized R-o-F data transmission which was awarded by Most honorable (MH) title. Moreover, his research paper is in preparation process which presents a novel approach of Optical Single Sideband (OSSB) modulation based on different electrical phase shifts using a dual-drive Mach–Zehnder modulator to support the connections in Passive Optical Networks (PONs) for tunable working frequency without re-adjustment.

Objectives: Due to the high free-space path loss at THz frequencies, moderate output powers and receiver sensitivities, future mobile THz applications such as THz communications but also mobile THz sensing for material identification (security, material science) must utilize meta-surfaces providing directive and steerable THz beams. The aim of this research is to investigate approaches for THz beam steering (Challenge II) and to integrate photonic phase shifters and wideband optical true-time-delays with mediated THz sources developed in the network (Challenge V) to demonstrate <1 THz beam steering. Expected Results: Optically mediated antennas array providing directive and steerable beams at up to 1THz Planned secondment(s): to FTMC (Dr. Irmantas Kašalynas), M10 for 1 month, on training in solid state THz sources and spectroscopic THz imaging to TRT (Dr. Daniel Dolfi), M16 for 1 month, for low-phase noise optical THz generation using TRTs dual-mode lasers to DAS (Dr. Valentin Polo), M28 for 2 months, for exp. testing of beam-steering arrays in spectroscopic imagers

Objectives: The purpose of this project is to develop arrays of photonic mediated THz sources to tackle the actual power limitations. Currently, the safe saturation current for THz photodiodes is below 10 mA allowing up to about a few 100 µW output power at 300 GHz. This research project will develop a novel 300 GHz multilayer waveguide technology for hybrid integration with a THz photodiode array. The aim is further to exploit HHI’s polymer board technology or SiN photonics for low-low power splitter as optical feeder and TRTs dual-mode laser for low-phase noise THz generation. This work addresses low-low THz waveguides and directive antennas (Challenge IV), high-power THz photodiode arrays as optically-mediated THz sources and photonic integration (Challenge I & V) and thus it will contribute to overcoming the challenges 1, 4 and 5. Expected Results: Low-phase noise, frequency stable and high-power optically-mediated THz sources for optical THz communications and as photonic LO for pumping mixers (e.g. SIS or low-barrier SD) in space and radioastronomy. Planned secondment(s): to ULIL (Prof. Guillaume Ducournau), M12 for 1 month, for round-robin characterization of THz photodiodes to HHI (Prof. Björn Globisch), M15 for 1.5 months, for designing the polymer-based low-loss optical power splitter to ACST (Dr. Oleg Cojocari), M 30 for 2 months, pumping ACSTs low-barrier SBD mixers with optical THz sources