Terahertz photonics

My research interests are broadly centred to the investigation of terahertz science and technology. My main interest consists in the investigation of active plasmonic/metamaterial devices based on 2D materials, e.g. graphene, for the realization of integrated fast optoelectronic devices, such as amplitude, frequency and polarization modulators and detectors, for spectroscopic, imaging and communication applications. I am actively involved in other areas of research related to terahertz photonics, such as engineering of terahertz quantum cascade lasers, waveguides, and microscopy. In parallel, I am active in laser-assisted processing of raw materials, such as plastics, for the future development of the green economy.

Key research areas

  • Physics-based modelling of creep behaviour for nuclear cladding materials
  • Dislocation-based modelling for multi-step metal forming process
  • Development of fundamental polycrystal modelling framework

Research themes

Terahertz integrated optoelectronic devices

Hybrid metamaterial/graphene modulators and detectors for the development of the next generation of terahertz optoelectronic devices.


Fig 1: Tuneable electromagnetically induced transparency in coupled metamaterial resonators actively damped by graphene. From Adv. Optical Mater. 1800570 (2018).


Fig 2: Fast room-temperature terahertz detector based on interdigitated bow-tie antennas contacting graphene. From ACS Photonics, 3, 1747–1753, (2016).

The aim of this research consists in the investigation of a novel class of integrated optoelectronic devices based on the interplay between graphene and metamaterials and operating in the Terahertz frequency range. The THz spectral region is particularly appealing for many applications, ranging from spectroscopy to communications, to imaging and astronomy. The basic optoelectronic building blocks capable of actively manipulating this radiation are currently missing, thus hindering its full exploitation in fundamental research and in industrial applications. The aim is to provide such tools by combining metamaterials unique features, such as compactness, versatility and high-efficiency together with bi-dimensional materials, such as graphene.

Key publications

• S. Kindness, N. Almond, B. Wei, R. Wallis, V. Kamboj, P. Braeuninger-Weimer, S. Hofmann, H. E. Beere, D. A. Ritchie, R. Degl'Innocenti ”Active control of electromagnetically induced transparency in a coupled plasmonic resonator array with graphene for continuous frequency control of terahertz radiation” Adv. Optical Mater. 1800570 (2018).

• R. Degl'Innocenti, L. Xiao, S.Kindness, V. Kamboj, B. Wei, P. Braeuninger-Weimer, K. Nakanishi, A. Aria, S. Hofmann, H. Beere, and D. Ritchie “Bolometric detection of terahertz quantum cascade lasers with graphene-plasmonic antenna arrays” Journal of Physics D invited article 50(17),17400, (2017)

• R. Degl'Innocenti, L. Xiao, D. S. Jessop, S. J. Kindness, Y. Ren, H. Lin, J. A. Zeitler, J. A. Alexander-Webber, H. J. Joyce, P. Braeuninger-Weimer, S. Hofmann, H. E. Beere and D. A. Ritchie “Fast room temperature detection of terahertz quantum cascade lasers with graphene loaded bow-tie plasmonic antenna arrays” ACS Photonics, 3, 1747–1753, (2016)

• D. S. Jessop, S. J. Kindness, L. Xiao, P. Braeuninger-Weimer, H. Lin, Y. Ren, C. X. Ren, S. Hofmann, J. A. Zeitler, H. E. Beere, D. A. Ritchie and R. Degl'Innocenti “Graphene based plasmonic terahertz amplitude modulator operating above 100 MHz”, Appl. Phys Lett. 108, 171101 (2016)

• R. Degl'Innocenti, D. S. Jessop, C. W. O. Sol, L. Xiao, S. J. Kindness, H. Lin, J. A. Zeitler, P. Braeuninger-Weimer, S. Hofmann, Y. Ren, V. S. Kamboj, J. Griffiths, H. E. Beere and D. A. Ritchie “Fast modulation of terahertz quantum cascade lasers using graphene loaded plasmonic antennas” ACS Photonics 3, 464-470, (2016).


“THz metamaterial/graphene optoelectronic modulators” EPSRC grant EP/S019383/1 (PI: 15/1/2019-> 14/1/2021).

“THz graphene/metamaterial active frequency modulators” Royal Society research grant RSG\R1\180148 (PI 15/3/2018->15/3/2019)

Terahertz photonics including microscopy and quantum cascade lasers

This theme covers several research fields involving THz photonics, with a specific interest in microscopy and quantum cascade lasers.

In collaboration with other leading research groups in UK and worldwide, I am interested in all the different areas where THz Photonics find application in, such as quantum electronics, imaging and waveguiding. In particular I am actively investigating novel imaging techniques, including near-field nanoscopy and self-mixing imaging in combination with quantum cascade lasers. These laser sources offer a straightforward implementation and synergy with metamaterial/graphene modulators, at the same time providing a unique platform for the investigation of nonconventional optical microcavities.

Fig 1: Hyperuniform cavity THz quantum cascade laser based on pillars etched in the laser active region, planarized and wire-bonded for electrical contact. From Sci. Rep. 6, 19325 (2016).


Fig 2: Terahertz scattering near-field optical microscope (s-SNOM) based on a quantum cascade laser implemented as both source and detector in a self-mixing scheme, yielding a spatial resolution > /1000. From ACS Photonics, 4(9), 2150–2157, (2017).

Key publications:

• B. Wei, S. Kindness, N. Almond, R. Wallis, Y. Wu, Y. Ren, S.-C. Shi, P. Braeuninger-Weimar, S. Hofmann, H. Beere, D. Ritchie, and R. Degl'Innocenti “Amplitude stabilization and active control of a terahertz quantum cascade laser with a graphene loaded split-ring-resonator array” Appl. Phys. Lett. 112, 201102 (2018).

• R. Degl'Innocenti, R. Wallis, B. Wei, L. Xiao, S. J. Kindness, O. Mitrofanov, P. Braeuninger-Weimer, S. Hofmann, H. E. Beere, D. A. Ritchie “Terahertz Nanoscopy of Plasmonic Resonances with a Quantum Cascade Laser” ACS Photonics, 4(9), 2150–2157, (2017).

• S. J. Kindness, D. S. Jessop, B. Wei, R. Wallis, V. S. Kamboj, L. Xiao, Y. Ren, P. Braeuninger-Weimer, A. I. Aria, S. Hofmann, H. E. Beere, D. A. Ritchie, R. Degl'Innocenti “External amplitude and frequency modulation of a terahertz quantum cascade laser using metamaterial/graphene devices”, Scientific Reports 7(1), 7657 (2017)

• A. Pitanti, L. Masini, L. Baldacci, M. S. Vitiello, R. Degl'Innocenti, H. Beere, D. Ritchie, and A. Tredicucci. “Continuous wave laser operation of a dipole-antenna terahertz microresonator” Light: Science & Applications, 6(10), e17054 (2017).

• R. Degl'Innocenti, Y. Shah, L. Masini, A. Ronzani, A. Pitanti, Y. Ren, D. Jessop, A. Tredicucci, H. Beere and D. Ritchie “Hyperuniform disordered terahertz quantum cascade laser” Scientific Report 6, 19325 (2016).


“HyperTerahertz - High precision terahertz spectroscopy and microscopy” EPSRC program grant EP/P021859/1 (CO-I 1/6/2017-> 31/5/2022)

Laser-assisted material processing for the green economy

This research area is focused on the investigation of laser-assisted techniques for recycling of materials such as rubber and plastics.

The aim is to use powerful solid-state lasers to aid the disposal, via thermal decomposition, of common materials in industrial processes, such as rubber or plastics. The target consist in treat these items in a controlled, reproducible and environment friendly system capable of recycling the interesting by-products of the reaction.


"Laser-assisted controlled pyrolysis of rubber/bitumen raw materials" Industrial sponsor: Synecom (Bg, Italy) / Kima EKO Engineering (Bg, Italy). (25/4/2018-15/6/2019).

Key information


  • Terahertz time domain spectrometer
  • Technology Centre clean room facility


  • EPSRC Engineering and Physical Sciences Research Council
  • Royal society