Abstract- Antenna Integrated THz Uni-Traveling Carrier Photodiodes

Cyril C. Renaud, Michele Natrella,   Chris Graham,  James Seddon,   Frederic Van Dijk,  Alwyn J. Seeds

http://ieeexplore.ieee.org/document/7979505/

High-speed photodiodes are a key element of numerous photonic systems. With the development of potential applications in the THz range such as sensing, spectroscopy, and wireless transmission, devices with integrated antenna covering the frequency range from 0.1 to 3 THz will become essential. In this paper, we discuss the development of uni-traveling carrier photodiodes with integrated antennas to address that need. In particular we develop the key elements to present a simple design tool for the efficient integration of the device with an antenna. We also present fabricated device results that show the highest figure of merit to date for photonic THz emitters. When integrated with well-matched antennas the devices have achieved record level of power up to 1 THz compared to other published photomixers. We also show that these devices can be used as receivers at frequencies up to 560 GHz with conversion losses of the order of 30 dB.

Abstract- Injection locking of a terahertz quantum cascade laser to a telecommunications wavelength frequency comb

Joshua R. Freeman, Lalitha Ponnampalam, Haymen Shams, Reshma A. Mohandas, Cyril C. Renaud, Paul Dean, Lianhe Li, A. Giles Davies, Alwyn J. Seeds, and Edmund H. Linfield

https://www.osapublishing.org/optica/abstract.cfm?uri=optica-4-9-1059

High-resolution spectroscopy not only can identify atoms and molecules but also can provide detailed information on their chemical and physical environment and relative motion. In the terahertz frequency region of the electromagnetic spectrum, where many molecules have fundamental vibrational modes, there is a lack of powerful sources with narrow linewidths that can be used for absorption measurements or as local oscillators in heterodyne detectors. The most promising solid-state source is the THz frequency quantum cascade laser (QCL), however, the linewidth of this compact semiconductor laser is typically too broad for many applications, and its frequency is not directly referenced to primary frequency standards. In this work, we injection lock a QCL operating at 2 THz to a compact fiber-based telecommunications wavelength frequency comb, where the comb line spacing is referenced to a microwave frequency reference. This results in the QCL frequency locking to an integer harmonic of the microwave reference, and the QCL linewidth reducing to the multiplied linewidth of the microwave reference, <100  Hz$<100\mathrm{Hz}$. Furthermore, we perform phase-resolved detection of the locked QCL and measure the phase noise of the locked system to be −75  dBc/Hz$-75\mathrm{dBc}/\mathrm{Hz}$ at 10 kHz offset from the 2 THz carrier.

Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Abstract-Advances in terahertz communications accelerated by photonics

• Tadao Nagatsuma,
• Guillaume Ducournau
• & Cyril C. Renaud

http://www.nature.com/nphoton/journal/v10/n6/full/nphoton.2016.65.html

Almost 15 years have passed since the initial demonstrations of terahertz (THz) wireless communications were made using both pulsed and continuous waves. THz technologies are attracting great interest and are expected to meet the ever-increasing demand for high-capacity wireless communications. Here, we review the latest trends in THz communications research, focusing on how photonics technologies have played a key role in the development of first-age THz communication systems. We also provide a comparison with other competitive technologies, such as THz transceivers enabled by electronic devices as well as free-space lightwave communications.

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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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