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Ultrafast & Terahertz Photonics: Publications

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Simultaneous measurement of orthogonal terahertz fields via an emission multiplexing scheme

Diagram

Huiliang Ou, Rayko Ivanov Stantchev, Xuequan Chen, Thierry Blu, Mykhaylo Semtsiv, William Ted Masselink, A. Hernandez Serrano, G. Costa, J. Young, N. Chopra, J. Lloyd-Hughes, and E. Pickwell-MacPherson
Optics Express 32, 5567 (Feb 2024)

Fri 02 Feb 2024, 16:17 | Tags: THz spectroscopy, THz components, MacPherson, 2024, Lloyd-Hughes

Quantifying photoluminescence variability in monolayer molybdenum disulfide films grown by chemical vapour deposition

Shaping

BFM Healy, SL Pain, J. Lloyd-Hughes, NE Grant and JD Murphy
Materials Research Express (Jan 2024)

Tue 23 Jan 2024, 07:24 | Tags: nanomaterials, photoluminescence, 2024, Lloyd-Hughes

The 3237 cm−1 diamond defect: Ultrafast vibrational dynamics, concentration calibration, and relationship to the N3VH0 defect

3237

T.J. Keat, D. J. L. Coxon, R.J. Cruddace, V. G. Stavros, M. E. Newton, and J. Lloyd-Hughes
Diamond and Related Materials 141 110661 (Jan 2024)

Thu 07 Dec 2023, 12:17 | Tags: nanomaterials, 2024, Lloyd-Hughes, ultrafast

Optimum Optical Designs for Diffraction-Limited Terahertz Spectroscopy and Imaging Systems Using Off-Axis Parabolic Mirrors

Shaping

N. Chopra and J. Lloyd-Hughes
J Infrared Milli Terahz Waves 44, 981 (Nov 2023)


Terahertz Emission via Optical Rectification in a Metal-Free Perovskite Crystal

mDABCO

Nathaniel P. Gallop, Dumitru Sirbu, David Walker, James Lloyd-Hughes, Pablo Docampo and Rebecca L. Milot
ACS Photonics 10 4022, (October 2023)

Thu 02 Nov 2023, 07:36 | Tags: THz spectroscopy, Milot, perovskites, Lloyd-Hughes, 2023, ultrafast, highlight

High-bandwidth perovskite photonic sources on silicon

LED

A. Ren, H. Wang, L. Dai, J. Xia, E. Butler-Caddle, J.A. Smith, ... S.A. Hindmarsh, A.M. Sanchez, J. Lloyd-Hughes, S. J Sweeney, ... and Wei Zhang
Nature Photonics 17, 798–805 (July 2023)


Resolving the Ultrafast Charge Carrier Dynamics of 2D and 3D Domains within a Mixed 2D/3D Lead-Tin Perovskite

CNT

Jake D. Hutchinson, Edoardo Ruggeri, Jack M. Woolley, Géraud Delport, Samuel D. Stranks, Rebecca L. Milot
Advanced Functional Materials 2305736, (August 2023)

Mon 07 Aug 2023, 11:41 | Tags: THz spectroscopy, Milot, perovskites, 2023, ultrafast

Spectroscopic insight on impact of environment on natural photoprotectants

Diagram

A. Whittock, X. Ding, X. Ramirez Barker, N. Auckloo, R. Sellers, J.M. Woolley V. Krishnan, C. Marine, C. Corre, E. Pickwell-MacPherson and V.G. Stavros
Chem. Sci. 14, 6763 (June 2023)

Wed 28 Jun 2023, 08:00 | Tags: THz spectroscopy, MacPherson, 2023, biomedical

Ultrafast THz spectroscopy of carbon nanotube-graphene composites

CNT

M.G. Burdanova, A.P. Tsapenko, S. Ahmad, E.I. Kauppinen and J. Lloyd-Hughes
Nanotechnology 34 405203 , (June 2023)

Wed 28 Jun 2023, 07:26 | Tags: THz spectroscopy, nanomaterials, Lloyd-Hughes, 2023, ultrafast

The 2023 terahertz science and technology roadmap

Diagram

A. Leitenstorfer, ..., E. Pickwell-MacPherson, ... and J. Cunningham
J. Phys. D: Appl. Phys. 56, 223001 (April 2023)


Quantitative evaluation of transdermal drug delivery patches on human skin with in vivo THz-TDS

Diagram

X. Ding, G. Costa, A. I. Hernandez-Serrano, R.I. Stantchev, G. Nurumbetov, D.M. Haddleton, and E. Pickwell-MacPherson
Bio. Opt. Express 14, 1146 (Feb 2023)

Tue 06 Jun 2023, 22:02 | Tags: THz spectroscopy, MacPherson, 2023, biomedical, highlight

Spectroscopic Insights into the Influence of Filling Carbon Nanotubes with Atomic Nanowires for Photophysical and Photochemical Applications

HgTe

Z. Hu, B. Breeze, M. Walker, E. Faulques, J. Sloan and J. Lloyd-Hughes
ACS Appl. Nano Mater. 6, 2883 (Feb 2023)

Wed 08 Feb 2023, 16:28 | Tags: nanomaterials, Lloyd-Hughes, 2023, ultrafast

Active THz beam shaping using a one-dimensional array of photoconductive emitters

Shaping

N. Chopra, J. Deveikis and J. Lloyd-Hughes
Appl. Phys. Lett. 122 061102 (Feb 2023)

Tue 07 Feb 2023, 11:28 | Tags: THz spectroscopy, Lloyd-Hughes, THz imaging, 2023

Tunable THz flat zone plate based on stretchable single-walled carbon nanotube thin film

CNT THz Fresnel lenses

G.M. Katyba, N.I. Raginov, E.M. Khabushev, V.A. Zhelnov, A. Gorodetsky, D.A. Ghazaryan, M.S. Mironov, D.V. Krasnikov, Y.G. Gladush, J. Lloyd-Hughes, A.G. Nasibulin, A.V. Arsenin, V.S. Volkov, K.I. Zaytsev, and M.G. Burdanova
Optica 10, 53 (Jan 2023)

Fri 06 Jan 2023, 22:48 | Tags: THz components, Lloyd-Hughes, 2023

Terahertz photoconductance dynamics of semiconductors from sub-nanosecond to millisecond timescales

E-OPTP

E. Butler-Caddle, N.E. Grant, S.L. Pain, J.D. Murphy, K.D.G.I. Jayawardena and J. Lloyd-Hughes
Appl. Phys. Lett. 122 012101 (Jan 2023)

Tue 03 Jan 2023, 17:17 | Tags: THz spectroscopy, perovskites, Lloyd-Hughes, 2023, ultrafast, highlight

Dephasing Dynamics across Different Local Vibrational Modes and Crystalline Environments

PFID

T.J. Keat , D. J. L. Coxon, M. Staniforth, M. W. Dale, V. G. Stavros, M. E. Newton, and J. Lloyd-Hughes
Phys. Rev. Lett. 129 237401 (Nov 2022)

Tue 29 Nov 2022, 18:45 | Tags: Lloyd-Hughes, 2022, ultrafast, highlight

Multi-pixel photoconductive emitters for the controllable generation of azimuthal and radial terahertz beams ("Editor's Pick")

Multi-pixel emitters

J. Deveikis and J. Lloyd-Hughes
Optics Express 30 43293 (Nov 2022)

Thu 10 Nov 2022, 13:00 | Tags: THz spectroscopy, THz components, Lloyd-Hughes, 2022

Terahertz (THz) biophotonics technology: Instrumentation, techniques, and biomedical applications

Diagram

X. Chen, H. Lindley-Hatcher, R. I. Stantchev, J. Wang, K. Li, A. I. Hernandez-Serrano, Z. D. Taylor, E. Castro-Camus and E. Pickwell-MacPherson
Chem. Phys. Rev. 3, 011311 (June 2022)

Wed 01 Jun 2022, 09:45 | Tags: THz spectroscopy, MacPherson, 2022, biomedical, review

Optimized multilayer structure for sensitive THz characterization of thin-film glucose solutions

Diagram

X. Ding, A. I. Hernandez-Serrano, H. Lindley-Hatcher, R. I. Stantchev, J. Zhou and E. Pickwell-MacPherson
Optics Express 30, 18079 (May 2022)

Sun 01 May 2022, 20:55 | Tags: THz spectroscopy, MacPherson, 2022

Simulated and Experimental Verification for a Terahertz Specific Finite Rate of Innovation Signal Processing Method

Diagram

X. E. Ramirez Barker, R. I. Stantchev, A. I. Hernandez-Serrano and E. Pickwell-MacPherson
Sensors 22, 3387 (April 2022)

Thu 21 Apr 2022, 12:00 | Tags: THz spectroscopy, MacPherson

Zigzag HgTe Nanowires Modify the Electron–Phonon Interaction in Chirality-Refined Single-Walled Carbon Nanotubes

HgTe

Z. Hu, B. Breeze, R.J. Kashtiban, J. Sloan and J. Lloyd-Hughes
ACS Nano 16 6789 (Apr 2022)

Thu 07 Apr 2022, 22:37 | Tags: nanomaterials, photoluminescence, Lloyd-Hughes, 2022, ultrafast

Predicting Solar Cell Performance from Terahertz and Microwave Spectroscopy

THz round robin

H. Hempel, T.J. Savenjie, M. Stolterfoht, J. Neu, M. Failla, V.C. Paingad, P. Kužel, E.J. Heilweil, J.A. Spies, M. Schleuning, J. Zhao, D. Friedrich, K. Schwarzburg, L.D.A. Siebbeles, P. Dörflinger, V. Dyakonov, R. Katoh, M.J. Hong, J.G. Labram, M. Monti, E. Butler-Caddle, J. Lloyd-Hughes, M.M. Taheri, J.B. Baxter, T.J. Magnanelli, S. Luo, J.M. Cardon, S. Ardo, T. Unold
Advanced Energy Materials 2102776 (Feb 2022)

Tue 01 Mar 2022, 11:13 | Tags: photoluminescence, perovskites, Lloyd-Hughes, 2022, ultrafast

A Review of the Terahertz Conductivity and Photoconductivity of Carbon Nanotubes and Heteronanotubes

Review on CNTs

M.G. Burdanova, A.P. Tsapenko, M.V. Kharlamova, E.I. Kauppinen, B.P. Gorshunov, J. Kono and J. Lloyd-Hughes
Advanced Optical Materials 2101042 (Sept 2021)

Thu 30 Sep 2021, 22:28 | Tags: THz spectroscopy, nanomaterials, Lloyd-Hughes, review, 2021

Intertube Excitonic Coupling in Nanotube Van der Waals Heterostructures

1D van der Waals hetereostructures

M.G. Burdanova, M. Liu, M. Staniforth, Y. Zheng, R. Xiang, S. Chiashi, A. Anisimov, E. I. Kauppinen, S. Maruyama and J. Lloyd-Hughes
Advanced Functional Materials 2104969 (Sept 2021)

Tue 21 Sep 2021, 20:29 | Tags: nanomaterials, Lloyd-Hughes, ultrafast, 2021

Precise and accurate control of the ellipticity of THz radiation using a photoconductive pixel array

Multi-pixel emitters

C.D.W. Mosley, J. Deveikis and J. Lloyd-Hughes
Appl. Phys. Lett. 119 121105 (Sep 2021)

Tue 21 Sep 2021, 12:00 | Tags: THz spectroscopy, THz components, Lloyd-Hughes, 2021

Linear and Helical Cesium Iodide Atomic Chains in Ultranarrow Single-Walled Carbon Nanotubes: Impact on Optical Properties

CsI atomic chains

R.J. Kashtiban, M.G. Burdanova, A. Vasylenko, J. Wynn, P.V.C. Medeiros, Q. Ramasse, A.J. Morris, D. Quigley, J. Lloyd-Hughes and J. Sloan
ACS Nano 15 13389 (Aug 2021)

Tue 10 Aug 2021, 07:47 | Tags: nanomaterials, photoluminescence, Lloyd-Hughes, 2021

The 2021 ultrafast spectroscopic probes of condensed matter roadmap

roadmap

J. Lloyd-Hughes, P.M. Oppeneer, T. Pereira dos Santos, A. Schleife, S. Meng, M.A. Sentef, M. Ruggenthaler, A. Rubio, I. Radu, M. Murnane, X. Shi, H. Kapteyn, B. Stadtmüller, K.M. Dani, F.H. da Jornada, E. Prinz, M. Aeschlimann, R.L. Milot, M. Burdanova, J. Boland, T. Cocker and F. Hegmann
J. Phys.: Cond. Matt. 33 353001 (July 2021)


Hot electron cooling in InSb probed by ultrafast time-resolved terahertz cyclotron resonance

InSb cyclotron

C.Q. Xia, M. Monti, J.L. Boland, L.M. Herz, J. Lloyd-Hughes, M.R. Filip and M.B. Johnston
Phys. Rev. B 103 245205 (June 2021)

Tue 29 Jun 2021, 09:37 | Tags: THz spectroscopy, Lloyd-Hughes, 2021

Real time THz imaging—opportunities and challenges for skin cancer detection

Diagram

H. Lindley-Hatcher, R. I. Stantchev, X. Chen, A. I. Hernandez-Serrano, J. Hardwicke and E. Pickwell-MacPherson
Appl. Phys. Lett. 118, 230501 (June 2021)

Thu 10 Jun 2021, 12:30 | Tags: THz spectroscopy, MacPherson, THz imaging, biomedical, review, 2021

Layered Perovskites in Solar Cells: Structure, Optoelectronic Properties, and Device Design

Helen review

D. Sirbu, F. H. Balogun, R. L. Milot and P. Docampo
Advanced Energy Materials (May 2021)


Ultrafast, high modulation depth terahertz modulators based on carbon nanotube thin films

1D van der Waals hetereostructures

M.G. Burdanova, G.M. Katybab, R. Kashtiban, G.A. Komandin, E. Butler-Caddle, M. Staniforth, A.A. Mkrtchyan, D.V. Krasnikov, Y.G. Gladush, J.Sloan, A.G. Nasibulin and J. Lloyd-Hughes
Carbon 173 245 (Mar 2021)

Mon 01 Mar 2021, 00:00 | Tags: THz spectroscopy, THz components, nanomaterials, Lloyd-Hughes, 2021

Low cost and long-focal-depth metallic axicon for terahertz frequencies based on parallel-plate-waveguides

Diagram

A. I. Hernandez-Serrano and E. Pickwell-MacPherson
Scientific Reports 11, 3005 (February 2021)

Thu 04 Feb 2021, 13:20 | Tags: THz components, MacPherson, THz imaging, 2021

Hot carriers in mixed Pb-Sn halide perovskite semiconductors cool slowly while retaining their electrical mobility

Hot carrier temperatures

M. Monti, K.D.G.I. Jayawardena, E. Butler-Caddle, R.M.I. Bandara, J.M. Woolley, M. Staniforth, S.R.P. Silva and J. Lloyd-Hughes
Phys. Rev. B 102 245204 (Dec 2020) [ pdf ] [ ref ]

Thu 24 Dec 2020, 10:00 | Tags: THz spectroscopy, photoluminescence, perovskites, Lloyd-Hughes, 2020

Evaluation of in vivo THz sensing for assessing human skin hydration

Diagram

H. Lindley-Hatcher, A. I. Hernandez-Serrano, J. Wang, J. Cebrian, J. Hardwicke and E. Pickwell-MacPherson
J. Phys. Photonics 3, 014001 (December 2020)

Mon 14 Dec 2020, 13:00 | Tags: THz spectroscopy, MacPherson, biomedical, 2020

Exploiting Complementary Terahertz Ellipsometry Configurations to Probe the Hydration and Cellular Structure of Skin In Vivo

Diagram

X. Chen, Q. Sun, J. Wang, H. Lindley-Hatcher, E. Pickwell-MacPherson
Adv. Photonics Res. 2000024 (November 2020) [ pdf ] [ ref ]

Tue 10 Nov 2020, 10:00 | Tags: THz spectroscopy, MacPherson, biomedical, 2020

Nanotechnology for catalysis and solar energy conversion

, , , , , , , , , , , , , , , , ,

Mon 09 Nov 2020, 17:46 | Tags: THz spectroscopy, nanomaterials, Milot, perovskites, 2020, review

Evaluation of transdermal drug delivery using terahertz pulsed imaging

Diagram

J. Wang, H. Lindley-Hatcher, K. Liu, E. Pickwell-MacPherson
Biomedical Optics Express 11 4484 (August 2020) [ pdf ] [ ref ]

Thu 24 Sep 2020, 10:01 | Tags: MacPherson, THz imaging, biomedical, 2020

In-line evanescent-field-coupled THz bandpass mux/demux fabricated by additive layer manufacturing technology

Diagram

A. I. Hernandez-Serrano, S. J. Leigh and E. Pickwell-MacPherson
OSA Continuum 3, 2407 (August 2020)

Tue 25 Aug 2020, 12:45 | Tags: THz components, MacPherson, 2020

An Ultrafast Shakedown Reveals the Energy Landscape, Relaxation Dynamics and Concentration of the N3VH0 Defect in Diamond

Ultrafast shakedownD.J.L. Coxon, M. Staniforth, B.G. Breeze, S.E. Greenough, J.P. Goss, M. Monti, J. Lloyd-Hughes, V.G. Stavros, and M.E. Newton
J. Phys. Chem. Lett. 11, 6677 (July 2020) [ pdf (with SI) ] [ ref ]



Fri 17 Jul 2020, 22:00 | Tags: nanomaterials, Lloyd-Hughes, 2020

Emergent Antipolar Phase in BiFeO3-La0.7Sr0.3MnO3 Superlattice

W. Dong, J.J.P. Peters, D. Rusu, M. Staniforth, A. Brunier, J. Lloyd-Hughes, A.M. Sanchez and M. Alexe
Nano Lett. 20 8, 6045 (July 2020) [ pdf ] [ ref ]

Emergent antipolar phase



Tue 14 Jul 2020, 21:05 | Tags: nanomaterials, Lloyd-Hughes, 2020

Real-time terahertz imaging with a single-pixel detector

R. I. Stantchev, X. Yu, T. Blu and E. Pickwell-MacPherson
Nature Communications 11 2535 (May 2020) [ pdf ] [ ref ] Stantchev 2020

Thu 09 Jul 2020, 22:23 | Tags: THz components, MacPherson, 2020

Metal composition influences optoelectronic quality in mixed-metal lead-tin triiodide perovskite solar absorbers

M. T. Klug, R. L. Milot, J.B. Patel, T. Green, H. C. Sansom, M. D. Farrar, A. J. Ramadan, S. Martani, Z. Wang, B. Wenger, J. M. Ball, L. Langshaw, A. Petrozza, M. B. Johnston, L. M. Herz and H. J. Snaith
Energy & Environmental Science (May 2020)

Klug 2020



Fri 01 May 2020, 13:00 | Tags: THz spectroscopy, photoluminescence, Milot, perovskites, 2020

Ultrafast Optoelectronic Processes in 1D Radial van der Waals Heterostructures: Carbon, Boron Nitride, and MoS2 Nanotubes with Coexisting Excitons and Highly Mobile Charges

M.G. Burdanova, R.J. Kashtiban, Y. Zheng, R. Xiang, S. Chiashi, J.M. Woolley, M. Staniforth, E. Sakamoto-Rablah, X. Xie, M. Broome, J. Sloan, A. Anisimov, E.I. Kauppinen, S. Maruyama and J. Lloyd-Hughes
Nano Lett. 20 5, 3560 (Apr 2020) [ free e-print ] [ preprint pdf ] [ ref ]

1D van der Waals hetereostructuresHeterostructures built from 2D, atomically thin crystals are bound by the van der Waals force and exhibit unique optoelectronic properties. Here, we report the structure, composition and optoelectronic properties of 1D van der Waals heterostructures comprising carbon nanotubes wrapped by atomically thin nanotubes of boron nitride and molybdenum disulfide (MoS2). The high quality of the composite was directly made evident on the atomic scale by transmission electron microscopy, and on the macroscopic scale by a study of the heterostructure’s equilibrium and ultrafast optoelectronics. Ultrafast pump–probe spectroscopy across the visible and terahertz frequency ranges identified that, in the MoS2 nanotubes, excitons coexisted with a prominent population of free charges. The electron mobility was comparable to that found in high-quality atomically thin crystals. The high mobility of the MoS2 nanotubes highlights the potential of 1D van der Waals heterostructures for nanoscale optoelectronic devices.




Broadband amplitude, frequency, and polarization splitter for terahertz frequencies using parallel-plate waveguide technology

A. I Hernandez-Serrano, D. M. Mittleman and E. Pickwell-MacPherson
Optics Letters 45 1208 (Feb 2020) [ pdf ] [ ref ]

SchematicIn this Letter, we report a broadband frequency/polarization demultiplexer based on parallel-plate waveguides (PPWGs) for terahertz (THz) frequencies. The fabrication and experimental validation of this polarization sensitive demultiplexer is demonstrated for the range from 0.2 to 1 THz. Upgrading the demultiplexer by adding a second demultiplexer stage, a fifty-fifty amplitude splitter is also demonstrated in the same frequency range. The multiplexer is based on a stainless-steel traveling-wave antenna, exhibiting strong mechanical robustness. This unique device exhibits three splitting mechanisms in the same device: amplitude, polarization, and frequency splitting. This is a significant improvement for the next generation of THz passive components for communication purposes.

Tue 25 Feb 2020, 12:00 | Tags: THz spectroscopy, THz components, MacPherson, 2020

Landau polaritons in highly nonparabolic two-dimensional gases in the ultrastrong coupling regime

J. Keller, G. Scalari, F. Appugliese, S. Rajabali, M. Beck, J. Haase, C.A. Lehner, W. Wegscheider, M. Failla, M. Myronov, D.R. Leadley, J. Lloyd-Hughes, P. Nataf, and J. Faist
Physical Review B 101:075301 (Feb 2020) [ pdf ][ ref ]

Keller 2020We probe ultrastrong light-matter coupling between metallic terahertz metasurfaces and Landau-level transitions in high-mobility two-dimensional electron and hole gases. We utilize heavy-hole cyclotron resonances in strained Ge and electron cyclotron resonances in InSb quantum wells, both within highly nonparabolic bands, and compare our results to well-known parabolic AlGaAs/GaAs quantum well systems. Tuning the coupling strength of the system by two methods, lithographically and by optical pumping, we observe a behavior clearly deviating from the standard Hopfield model previously verified in cavity quantum electrodynamics: an opening of a lower polaritonic gap.



Mon 17 Feb 2020, 23:27 | Tags: THz spectroscopy, nanomaterials, Lloyd-Hughes, 2020

Approaching the Shockley-Queisser limit for fill factors in lead–tin mixed perovskite photovoltaics

K.D.G.I. Jayawardena, R.M.I. Bandara, M. Monti, E. Butler-Caddle, T. Pichler, H. Shiozawa, Z. Wang, S. Jenatsch, S.J. Hinder, M.G. Masteghin, M. Patel, H.M. Thirimanne, W. Zhang, R.A. Sporea, J. Lloyd-Hughes and S. R. P. Silva
J. Mater. Chem. A 8 693 (Jan 2020) [ pdf ] [ ref ]

GABr paperThe performance of all solar cells is dictated by charge recombination. A closer to ideal recombination dynamics results in improved performances, with fill factors approaching the limits based on Shockley-Queisser analysis. It is well known that for emerging solar materials such as perovskites, there are several challenges that need to be overcome to achieve high fill factors, particularly for large area lead-tin mixed perovskite solar cells. Here we demonstrate a strategy towards achieving fill factors above 80% through post-treatment of a lead-tin mixed perovskite absorber with guanidinium bromide for devices with an active area of 0.43 cm2. This bromide post-treatment results in a more favourable band alignment at the anode and cathode interfaces, enabling better bipolar extraction. The resulting devices demonstrate an exceptional fill factor of 83%, approaching the Shockley–Queisser limit, resulting in a power conversion efficiency of 14.4% for large area devices.



Mon 06 Jan 2020, 14:07 | Tags: THz spectroscopy, photoluminescence, perovskites, Lloyd-Hughes, 2020

A Robust Protocol for In Vivo THz Skin Measurements

H. Lindley-Hatcher, A. I Hernandez-Serrano, Q. Sun, J. Wang, J. Cebrian, L. Blasco, E. Pickwell-MacPherson
J Infrared Milli Terahz Waves 40 980 (August 2019) [ pdf ] [ ref ]

MethodThis work presents an experimental setup to control the way in which pressure interferes with the repeatability of in vivo THz skin measurements. By integrating a pressure sensor circuit into our THz system, it is possible to identify which measurements were taken within a previously specified pressure range. The live response of the pressure sensor helps to acquire data within the desired pressure leading to greater consistency of data between measurements. Additionally, a protocol is proposed to help achieve repeatable results and to remove the effects of the natural variation of the skin through the course of the day. This technique has been shown to be able to quantify the changes induced in the skin following the application of a moisturising skin product and shows the measured result to be significantly different from natural skin variation. This research therefore prepares the way for further studies on the effectiveness of different skin products using in vivo THz measurements.

Wed 28 Aug 2019, 09:00 | Tags: THz spectroscopy, MacPherson, 2019, biomedical

Ionic liquid gated carbon nanotube saturable absorber for switchable pulse generation

Y. Gladush, A. Mkrtchyan, D. Kopylova, A. Ivanenko, B. Nyushkov, S. Kobtsev, A. Kokhanovskiy, A. Khegai, M. Melkumov, M.G. Burdanova, M. Staniforth, J. Lloyd-Hughes and A.G. Nasibulin
Nano Letters 19 5836 (Aug 2019) [ pdf ] [ ref ]

Ionic liquid gated carbon nanotube saturable absorberMaterials with electrically tunable optical properties offer a wide range of opportunities for photonic applications. The optical properties of the single-walled carbon nanotubes (SWCNTs) can be significantly altered in the near infrared region by means of electrochemical doping. The states’ filling, which is responsible for the optical absorption suppression under doping, also alters the nonlinear optical response of the material. Here, for the first time, we report that the electrochemical doping can tailor the nonlinear optical absorption of SWCNT films and demonstrate its application to control pulsed fiber laser generation. With a pump-probe technique we show that under an applied voltage below 2 V the photo-bleaching of the material can be gradually reduced and even turned to photo-induced absorption. Furthermore, we integrated a carbon nanotube electrochemical cell on a side-polished fiber to tune the absorption saturation and implemented it into the fully polarization-maintaining fiber laser. We show that the pulse generation regime can be reversibly switched between femtosecond mode locking and microsecond Q-switching using different gate voltages. This approach paves the road towards carbon nanotube optical devices with tunable nonlinearity.

Fri 02 Aug 2019, 00:10 | Tags: nanomaterials, Lloyd-Hughes, 2019

Scalable interdigitated photoconductive emitters for the electrical modulation of terahertz beams with arbitrary linear polarization

C.D.W. Mosley, M. Staniforth, A. I. Hernandez Serrano, E. Pickwell-MacPherson and J. Lloyd-Hughes
AIP Advances 9, 045323 (Apr 2019) [ pdf ] [ ref ]

A multi-element interdigitated photoconductive emitter for broadband THz polarization rotation is proposed and experimentally verified. The device consists of separate pixels for the emission of horizontally and vertically polarized THz radiation. The broadband (0.3–5.0 THz) nature of the device is demonstrated, and the polarization angle of the generated far-field THz radiation is shown to be readily controlled by varying the relative bias voltage applied to the horizontally and vertically emitting pixels. The device is scalable in design, and with its simple method of polarization rotation it allows the modulation of the generated THz polarization at rates significantly faster than those achievable in ellipsometry systems based on mechanically rotating components.

Fri 26 Apr 2019, 19:08 | Tags: THz components, MacPherson, Lloyd-Hughes, 2019

Utilizing multilayer structures to enhance terahertz characterization of thin films ranging from aqueous solutions to histology slides

Q. Sun, K. Liu, X. Chen, X. Liu, A. I Hernandez-Serrano, E. Pickwell-MacPherson
Optics Letters 44 2149 (April 2019) [ pdf ] [ ref ]

GeometryWe propose a multilayer geometry to characterize thin-film samples in reflection terahertz time domain spectroscopy. Theory indicates that this geometry has higher sensitivity compared to ordinary transmission or reflection geometries when characterizing both low- and high-absorption samples. Pure water and water–ethanol mixtures are measured to verify the characterization accuracy of the proposed geometry and its capability to measure trace liquids. Paraffin-embedded oral cancer tissue is imaged to further show how the proposed geometry enhances the sensitivity for solid low-absorptive films.

Wed 17 Apr 2019, 17:00 | Tags: THz spectroscopy, THz components, MacPherson, 2019, biomedical

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