Research

Research Interests:

  • Optoelectronic components for terahertz generation, detection, and modulation.
  • Plasmonic waveguides for terahertz and millimeter-waves.
  • Micromachined circuits for terahertz applications.
  • Reconfigurable/broadband antennas and phased arrays.
  • Development of nano switches for microwave/millimeter-wave applications.
  • Novel NEMS circuits for microwave/millimeter-wave applications.
  • Hybrid integration of MMIC/RFIC circuits with MEMS components.
  • Periodic electromagnetic structures.
  • Development of novel micro/nanofabrication processes.
  • Hybrid / Monolithic packaging of MEMS components.
  • Discontinuity modeling of coplanar waveguide and microstrip structures.


Projects:

1. Project name: Development of higher order behavior models for NEMS and MEMS microstructures.

Funded by: TUBITAK (1001).

Position: Researcher (PI: Prof. Hüsnü Dal, METU Mechanical Eng.).

Duration: 2017-2020 (ongoing)

2. Project name: Development of X-band planar phase shifters.

Funded by: Ankara Yıldırım Beyazıt University (BAP).

Position: Principle Investigator.

Duration: 2016-2018 (completed)

3. Project name: Reconfigurable surface plasmon polariton waveguides for terahertz frequencies.

Funded by: TUBITAK (1001).

Position: Principle Investigator.

Duration: 2016-2019 (completed)

4. Project name: Beam steering, frequency reconfigurable terahertz photomixer array using nano-actuators.

Funded by: EU H2020 Marie Sklodowska Curie Program, Reintegration (RI) Grant.

Position: Principle Investigator.

Duration: 2015-2017 (completed)

5. Project name: Development of a reflectarray antenna.

Funded by: TUBITAK UZAY.

Position: Consultant.

Duration: 2015-2017 (completed)

6. Project name: Development of frequency reconfigurable, wideband, high radiation resistance photomixers and photoconductive antennas for terahertz frequencies (114E089).

Funded by: TUBITAK (3501).

Position: Principle Investigator.

Duration: 2014-2017 (completed)

7. Project name: Development of Miniature MEMS Switching Structures for Modulators in Terahertz Band.

Funded by: Ankara Yıldırım Beyazıt University (BAP).

Position: Principle Investigator.

Duration: 2013-2016 (completed)

8. Project name: Design and Development of Transmitter and Receiver Structures for Terahertz Frequency Band High Data Speed Communication System (113E230).

Funded by: TUBITAK (1001).

Position: Consultant (PI: Prof. Asaf Behzat Şahin, Ankara Yıldırım Beyazıt University, EE)

Duration: 2013-2016 (completed)


Current Research Activities:

Novel, Reconfigurable Source for Terahertz Band

1. K. Demir, H Bilgin, AB Sahin, M. Unlu, “Design of a frequency reconfigurable, terahertz antenna for photomixers,” Proc. International Conference on Infrared, Millimeter, and Terahertz Waves, Copenhagen, Denmark, Sep. 25-30, 2016.

2. K. Demir, AB Sahin, M. Unlu, “Design of a Frequency Reconfigurable, Terahertz Folded Antenna for Photomixers,” 2017 IEEE AP-S International Symposium and USNC/URSI National Radio Science Meeting, San Diego, California, USA, 9-14 July 2017.

Reconfigurable Spoof Surface Plasmon Polariton Waveguides and Components

1. MA., Unutmaz, M. Unlu, “Modelling of the Effective Dielectric Constant of Corrugated Planar Goubau Lines for Terahertz Band,” 2017 IEEE AP-S International Symposium and USNC/URSI National Radio Science Meeting, San Diego, California, USA, 9-14 July 2017.

2. MA., Unutmaz, M. Unlu, “Design of Spoof Surface Plasmon Polariton Based Terahertz Delay Lines,” 2017 IEEE AP-S International Symposium and USNC/URSI National Radio Science Meeting, San Diego, California, USA, 9-14 July 2017.

NEMS Switches and Nano-Actuators for Terahertz Frequencies

1. M., Kandaz, H., Dal, M. Unlu, “Analysis of Gold Micro-Beams with Higher Order Continuum Theories,” 88th GAMM Annual Meeting, Germany, 6-10 March 2017.

Past Research Activities:

High Performance Terahertz Modulators*

1. M. Unlu, M. Jarrahi, "Miniature Multi-Contact MEMS Switch for Broadband Terahertz Modulation," Optics Express, 22, 2014.

2. M. Unlu, M. R. Hashemi, C. W. Berry, S. Li, S.-H. Yang, M. Jarrahi, "Switchable scattering meta-surfaces for broadband terahertz modulation", Nature Scientific Reports, 4, 5708, DOI:10.1038/srep05708, 2014.

*These components were developed in the Terahertz Electronics Laboratory at University of Michigan (currently at UCLA).

Novel Circuit Topologies for Microwave and Millimeter-Wave Applications

Triple stub circuit topology*

1. M. Unlu, S. Demir, and T. Akin, "A 15–40-GHz Frequency Reconfigurable RF MEMS Phase Shifter," IEEE Transactions on Microwave Theory and Techniques, vol. 61, no. 8, pp. 2865-2877, Aug. 2013.

2. M. Unlu, S. Demir, and T. Akin, “Triple Stub Circuit Topology as Simultaneous Insertion Phase, Amplitude and Impedance Control Circuit for Phased Array Applications,” IET Microwaves, Antennas and Propagation, vol. 6, no. 13, pp. 1399-1406, Dec. 2012.

*These components were developed in the RF MEMS Group at Middle East Technical University.


Novel Components for Terahertz Band

Plasmonics-enhanced photoconductive terahertz emitters*

1. C. W. Berry, N. Wang, M. R. Hashemi, M. Unlu, and M. Jarrahi, “Significant Performance Enhancement in Photoconductive Terahertz Optoelectronics by Incorporating Plasmonic Contact Electrodes,” Nature Communications, 4, 1622, 2013.

2. C. W. Berry, M. R. Hashemi, M. Unlu, M. Jarrahi, "Plasmonic Photoconductive Antennas for Significant Terahertz Radiation Enhancement", Proc. IEEE International Antennas and Propagation Symposium, Orlando, FL, Jul. 7-12, 2013 (Best student paper award, 2nd place).

*These components were developed in the Terahertz Electronics Laboratory at University of Michigan (currently at UCLA).

Reconfigurable Antennas and Antenna Arrays

Electrically small, multi-band PIFA antennas*

1. A. Zohur, H. Mopidevi, D. Rodrigo, M. Unlu, L. Jofre, and B. A. Cetiner, “RF MEMS Reconfigurable Two-Band Antenna,” IEEE Antennas and Wireless Propagation Letters, vol. 12, pp. 72-75, Jan. 2013.

2. M. Unlu, H. Mopidevi, A. Zohur, and B. A. Cetiner, "Frequency reconfigurable, 220–5000 MHz, five-band RF MEMS PIFA," presented at the IEEE Int. Midwest Symp. Circuits and Systems (MWSCAS), Boise, ID, USA, Aug. 2012, pp. 65-68.

*These antennas were developed in the RF Micro-Nano Group at Cornell University.

Pixelled, pattern reconfigurable antennas*

1. D. Rodrigo, Y. Damgaci, M. Unlu, L. Jofre, and B. A. Cetiner, “Small pixelled antenna with MEMS-Reconfigurable radiation pattern,” presented at the IEEE Int. Antennas and Propagation Symp., Toronto, Ontario, Canada, Jul. 2010, pp. 1-4.

2. D. Rodrigo, Y. Damgaci, M. Unlu, B. A. Cetiner, J. Romeu and L. Jofre, “Antenna reconfigurability based on a novel parasitic pixel layer,” European Conf. on Antennas and Propagation, Rome, Italy, Apr. 2011, pp. 3497-3500.

*These antennas were developed in the RF Micro-Nano Group at Cornell University.

Frequency reconfigurable antennas*

1. E. Erdil, K. Topalli, M. Unlu, O. Aydin Civi, and T. Akin, "Frequency tunable microstrip patch antenna using RF MEMS technology," IEEE Trans. Antennas and Propagation, vol. 55, no. 4, pp. 1193-1196, Apr. 2007.

2. E. Erdil, K. Topalli, M. Unlu, I. Istanbulluoglu, E. U. Temocin, H. I. Atasoy, O. Bayraktar, O. A. Civi, S. Demir, S. Koc, T. Akin, “Reconfigurable slot antenna with fixed-fixed beam type RF MEMS capacitors,” European Conference on Antennas and Propagation, Nice, France, 6-10 Nov. 2006.

*These antennas were developed in the RF MEMS Group at Middle East Technical University.

Impedance Tuners

Reconfigurable double-stub tuners*

1. M. Unlu, K. Topalli, H. I. Atasoy, S. Demir, O. Aydin Civi, and T. Akin, “Hybrid Connection of RF MEMS and SMT Components in an Impedance Tuner,” AEU International Journal of Electronics and Communications, vol. 64, no. 8, pp. 748-756, Aug. 2010.

2. M. Unlu, K. Topalli, H. I. Atasoy, E. U. Temocin, I. Istanbulluoglu, O. Bayraktar, S. Demir, O. Aydin-Civi, S. Koc, and T. Akin, “A reconfigurable RF MEMS impedance tuner for impedance matching of a two-stage low noise amplifier,” 7th Workshop on MEMS for MilimeterWave Communications (MEMSWAVE), pp. 115-118, Orvieto, Italy, 27-30 Jun. 2006.

*These components were developed in the RF MEMS Group at Middle East Technical University.

Reconfigurable triple-stub tuners*

1. M. Unlu, K. Topalli, H. I. Atasoy, E. U. Temocin, I. Istanbulluoglu, O. Bayraktar, S. Demir, O. A. Civi, S. Koc, and T. Akin, “A reconfigurable RF MEMS triple stub impedance matching network,” European Microwave Conference 2006, Manchester, United Kingdom, pp. 1370-1373, 10-15 Sep. 2006.

2. M. Unlu, H. I. Atasoy, S. Demir, O. Aydin Civi, S. Koc, and T. Akin, "Double stub and triple stub RF MEMS impedance tuners," Proceedings of 8th International Symposium on RF MEMS and RF Microsystems, MEMSWAVE, Barcelona, Spain, pp. 169-172, 26-29 Jun. 2007.

3. M. Unlu, K. Topalli, S. Demir, O. Aydin Civi, S. Koc, and T. Akin, “Design and modeling of a reconfigurable triple stub impedance matching network using Distributed MEMS Transmission Lines,” 5th Workshop on MEMS for MilimeterWave Communications (MEMSWAVE), pp. I17-I20, Uppsala, Sweden, 30 Jun.-2 Jul. 2004.

*These components were developed in the RF MEMS Group at Middle East Technical University.

MEMS Switches

Metal and capacitive contact SPST switches*

1. K. Topalli, M. Unlu, H. I. Atasoy, O. A. Civi, S. Demir, and T. Akin, “Empirical Formulation of Bridge Inductance in Inductively Tuned RF MEMS Shunt Switches,” Progress In Electromagnetics Research, PIER 97, pp. 343-356, 2009.

2. H. I. Atasoy, K. Topalli, M. Unlu, I. Istanbulluoglu, E. U. Temocin, O. Bayraktar, S. Demir, O. Aydin-Civi, S. Koc, and T. Akin, “Metal-to-metal and capacitive contact RF MEMS shunt switch structures,” 7th Workshop on MEMS for MilimeterWave Communications (MEMSWAVE), pp. 154-156, Orvieto, Italy, 27‑30 Jun. 2006.

*These components were developed in the RF MEMS Group at Middle East Technical University.

Periodic Structures

Distributed MEMS transmission lines (DMTLs)*

1. K. Topalli, M. Unlu, S. Demir, O. Aydin Civi, S. Koc, and T. Akin, “A new approach for modeling Distributed MEMS Transmission Lines,” IEE Proc. Microwaves, Antennas & Propagation, vol. 153, pp. 152-162, Apr. 2006.

2. M. Unlu, K. Topalli, S. Demir, O. Aydin Civi, S. Koc, and T. Akin, “A Parametric Study On Modeling Distributed Mems Transmission Lines”, 34th European Microwave Conference, pp.1157-1160, Amsterdam, The Netherlands, Oct. 11‑15, 2004.

*These components were developed in the RF MEMS Group at Middle East Technical University.