Abstract-Comparison of Optical Single Sideband Techniques for THz-over-fiber Systems

Luis Gonzalez Guerrero,  Haymen Shams,  Irshaad Fatadin,  Martyn Fice, Mira Naftaly,  Alwyn Seeds, Cyril Renaud

https://ieeexplore.ieee.org/document/8570768

The use of single sideband (SSB) signals and envelope detection is a promising approach to enable the use of economic free-running lasers in photonic THz communications. To combat the signal-signal beat interference (SSBI) associated with envelope detection, broad guard bands (GBs) may be used given the large unregulated spectrum available at THz frequencies (100 GHz - 10 THz). In this scenario, the conventional way of generating SSB signals through a digital SSB filter (here referred to as the CSSB scheme) would require quite high analog digital-to-analog converter (DAC) bandwidths. Digital virtual SSB (DVSSB) and analog virtual SSB (AVSSB) have been proposed in direct-detection optical systems for relaxing the DAC bandwidth requirements. In this paper, we compare the three techniques through simulations and implement them, for the first time, in a THz-over-fiber (ToF) system operating at 250 GHz. For the transmission experiments we employ 5 GBd 16-QAM signals with three different GBs (5.5 GHz, 4.75 GHz and 3.5 GHz). The simulations show that the best performance is obtained with the AVSSB technique, while the worst is obtained with the DVSSB scheme, where the quality of the generated sideband degrades with carrier-to-sideband power ratio. In the experimental transmissions, where receiver noise was the main source of noise, similar behavior was found between the three techniques. At the 3.5 GHz GB, however, the DVSSB exhibited a penalty of 1 dB with respect to the other two. This is likely to be due to nonlinear distortions caused by the increase in the virtual tone power.

Abstract-Photonics, Fiber and THz Wireless Communication

Haymen Shams and Alwyn Seeds

https://www.osapublishing.org/opn/abstract.cfm?uri=opn-28-3-24&origin=search

Optical-fiber’s long-haul strengths, coupled with improvements in terahertz wireless signal generation and handling with photonic technology, could constitute part of the solution for a data-hungry society.

© 2017 Optical Society of America

Abstract-Photonics, Fiber and THz Wireless Communication

Haymen Shams and Alwyn Seeds

https://www.osapublishing.org/opn/abstract.cfm?uri=opn-28-3-24&origin=search

Optical-fiber’s long-haul strengths, coupled with improvements in terahertz wireless signal generation and handling with photonic technology, could constitute part of the solution for a data-hungry society.

© 2017 Optical Society of America

Abstract-Accurate equivalent circuit model for millimetre-wave UTC photodiodes

Michele Natrella, Chin-Pang Liu, Chris Graham, Frederic van Dijk, Huiyun Liu, Cyril C. Renaud, and Alwyn J. Seeds
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-24-5-4698

We present a comprehensive study of uni-travelling carrier photodiode impedance and frequency photo-response supported by measurements up to 110 GHz. The results of this investigation provide valuable new information for the optimisation of the coupling efficiency between UTC-PDs and THz antennas. We show that the measured impedance cannot be explained employing the standard junction-capacitance/series-resistance concept and propose a new model for the observed effects, which exhibits good agreement with the experimental data. The achieved knowledge of the photodiode impedance will allow the absolute level of power emitted by antenna integrated UTCs to be predicted and ultimately maximized.

© 2016 Optical Society of America

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Abstract-TeraHertz Photonics for Wireless Communications

TeraHertz Photonics for Wireless Communications

Alwyn J. Seeds, Haymen Shams, Martyn J. Fice, and Cyril C. Renaud 

Journal of Lightwave Technology, Vol. 33, Issue 3, pp. 579-587 (2015)

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Acrobat PDF (621 KB) 

http://www.opticsinfobase.org/jlt/abstract.cfm?uri=jlt-33-3-579

Optical fibre transmission has enabled greatly increased transmission rates with 10 Gb/s common in local area networks. End users find wireless access highly convenient for mobile communication. However, limited spectrum availability at microwave frequencies results in per-user transmission rates limited to much lower values, e.g., 500 Mb/s for 5-GHz band IEEE 802.11ac. Extending the high data-rate capacity of optical fiber transmission to wireless devices requires greatly increased carrier frequencies. This paper will describe how photonic techniques can enable ultrahigh capacity wireless data distribution and transmission using signals at millimeter-wave and TeraHertz (THz) frequencies.

© 2014 OAPA

Conference paper-TeraHertz Photonics for Communications

Alwyn J. Seeds  »View Author Affiliations

http://dx.doi.org/10.1364/OFC.2014.Th4H.1

http://www.opticsinfobase.org/abstract.cfm?uri=OFC-2014-Th4H.1

Extending the high data-rate capacity of optical fibre transmission to wireless devices, requires greatly increased carrier frequencies. This tutorial will describe how photonic techniques can enable ultra-high capacity data transmission using signals at TeraHertz frequencies.

© 2014 OSA

Exploiting underused THz Spectrum

Collaboration between UCL, Cambridge, Leeds and the London Centre for Nanotechnology.

http://www.ee.ucl.ac.uk/research/cots-news

UCL, Cambridge, Leeds and the London Centre for Nanotechnology unite to unlock the THz region of the electromagnetic spectrum, opening it up for widespread scientific and commercial exploitation. Three of the UK's Russell Group universities are joining together to unlock the underused and unchartered terahertz (THz) region of the electromagnetic spectrum, the last unexploited part of the airwaves. UCL, Cambridge and Leeds Universities are pioneering research through a project called COTS (Coherent Terahertz Systems), funded by a £6.5m Engineering and Physical Sciences Research Council (EPSRC) grant. Lying between radio and optical frequencies, the bandwidth available is some 30 times greater than the entire allocated radio spectrum. Within 10 years it is expected there will be widespread applications using THz ranging from ultra-broadband wireless technology for indoor "super Wi-Fi" to THz sensing and imaging systems in production control, security and medical applications. The UK has pioneered the exploitation of the THz spectrum through companies such as Teraview, and is well placed to exploit the outcomes from this Programme to benefit the UK economy. Dr Don Arnone, CEO of Teraview, who gave a keynote speech on the 16th July 2013 in Cambridge at a gathering of THz academics and industry leaders called 'UK THz Day', said "The COTS research programme will help the UK to maintain pre-eminence in THz research and exploit it to establish UK leadership in wireless communications, in quantum information processing and in advanced imaging technology, especially for biomedicine. We are delighted to be working in collaboration with the world leading COTS researchers." The main reason why this resource has been so little used so far is the complexity, bulk, high power consumption and lack of coherence of current THz technologies. The COTS programme brings together the world leading teams that have pioneered THz quantum cascade lasers, microwave photonics and THz quantum state control to open up the THz spectrum for widespread scientific and commercial application, through the use for the first time of photonics-enabled coherent techniques. The team met in Cambridge on the 17th July with invited academics and industry leaders from across the UK, to discuss their research findings so far and plans to set up a UK THz research network. Principal Investigator for the programme, Professor Alwyn Seeds, Head of the Department of Electronic and Electrical Engineering at UCL, said: "This programme will enable us to address the THz spectrum with the same precision and sensitivity as is today possible at radio frequencies, leading to this underused part of the electromagnetic spectrum finally achieving its full scientific and commercial potential."

Abstract-Coherent terahertz photonics

 

 

 

Alwyn J. Seeds, Martyn J. Fice, Katarzyna Balakier, Michele Natrella, Oleg Mitrofanov, Marco Lamponi, Mourad Chtioui, Frederic van Dijk, Michael Pepper, Gabriel Aeppli, A. Giles Davies, Paul Dean, Edmund Linfield, and Cyril C. Renaud

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-21-19-22988

We present a review of recent developments in THz coherent systems based on photonic local oscillators. We show that such techniques can enable the creation of highly coherent, thus highly sensitive, systems for frequencies ranging from 100 GHz to 5 THz, within an energy efficient integrated platform. We suggest that such systems could enable the THz spectrum to realize its full applications potential. To demonstrate how photonics-enabled THz systems can be realized, we review the performance of key components, show recent demonstrations of integrated platforms, and give examples of applications.

© 2013 OSA

University of Leeds £6.5 million programme brings together world experts in terahertz research

http://www.engineering.leeds.ac.uk/faculty/news/2012/terahertz-research.shtml

Published Friday 9 March 2012

Researchers at the University of Leeds are to benefit from a £6.5 million programme into terahertz lasers with applications ranging from security to future quantum computers.

The programme, funded by the Engineering and Physical Sciences Research Council (EPSRC), will involve researchers from the School of Electronic and Electrical Engineering, University of Leeds; the Department of Electronic and Electrical Engineering, UCL; the London Centre for Nanotechnology; and the Cavendish Laboratory, University of Cambridge.

The terahertz (THz) frequency region is the last unexploited part of the electromagnetic spectrum.

Lying between radio and optical frequencies, the bandwidth available is some 30 times greater than the entire allocated radio spectrum.

The main reason why this resource has been so little used is the complexity, bulk, high power consumption and lack of coherence of current THz technologies.

The programme will bring together the world leading teams that have pioneered THz quantum cascade lasers, microwave photonics and THz quantum state control to open up the THz spectrum for widespread scientific and commercial application, through the use for the first time of photonics-enabled coherent techniques.

The programme aims to maintain this pre-eminence and exploit it to establish UK leadership in wireless communications, with a thousand-fold enhancement in bandwidth available to untethered devices; in quantum information processing with optically controlled gates in silicon, and in advanced imaging technology, especially for biomedicine.

Principal Investigator at Leeds, Professor Giles Davies, Pro-Dean for Research and Innovation in the Faculty of Engineering, said: "This is a fantastic opportunity for us to build on our pioneering and internationally-leading work on the growth, design, fabrication and measurement of terahertz frequency quantum cascade lasers. By developing photonic control of these devices, we will transform the application of terahertz technology across the physical, biological and medical sciences, and strengthen the UK’s leadership in this emerging field.”

Principal Investigator for the programme, Professor Alwyn Seeds, Head of the Department of Electronic and Electrical Engineering at UCL, said: "This programme will enable us to address the THz spectrum with the same precision and sensitivity as is today possible at radio frequencies, leading to this underused part of the electromagnetic spectrum finally achieving its full scientific and commercial potential."

For more information:

Contact: Paula Gould, University of Leeds Communications & Press Office: Tel 0113 343 8059