Resonant tunnelling diode-photodetectors and DFB lasers for optical communications

Zhang, Weikang (2020) Resonant tunnelling diode-photodetectors and DFB lasers for optical communications. PhD thesis, University of Glasgow.

Due to Embargo and/or Third Party Copyright restrictions, this thesis is not available in this service.


Resonant tunnelling diode (RTD)-based technique has been investigated for a few years, and RTD-based devices have been proven as one of the most promising solid-state mm-wave/THz sources which can operate at room temperature. RTDs have the advantages of ultra-high operating frequencies, the nonlinearity of the I-V characteristic, low power consumption and high integration capability. These features make RTD-based devices feasible to be utilised as transmitters and detectors for high-speed wireless communications, as well as the interfaces in the existing high-speed optical networks. With the advancement of fabrication processes, a variety of RTD-based devices have been developed, and their performances, such as the oscillation frequency and output power, have been continuously improving. For communication purposes, a number of demonstrations on RTD-based transceivers have been illustrated with transmission data rates from hundreds of Mbit/s to tens of Gbit/s, depending on the application scenarios. However, most studies are based on the all-electrical RTD devices, with an effort to improve the carrier frequencies and transmission data rates. Although the optical characteristics of RTDs have been widely investigated, research of the directly optical modulation of RTDs is still at an early stage. In this work, innovative research on RTD devices which employ semiconductor photoabsorption layer(s) is illustrated, with a series of measurements of RTD-photodetector (RTD-PD) devices being conducted. Specifically, the optical and electrical intensity modulations, as well as the short-range wireless transmission, are demonstrated. These experimental results highlight the potential of RTD devices for future high-speed optical/wireless communications.

The second topic of this thesis looks at the characteristic analyses of distributed feedback (DFB) lasers, in terms of both steady-state and dynamic performances. Firstly, some basic measurements are conducted to analyse and evaluate the quality of DFB lasers, including the steady-state light-current-voltage (LIV), spectrum and frequency response features. It is significant to accurately extract the intrinsic parameters which determine the modulation bandwidth of the devices. A new method, which is modified from the classic frequency response subtraction method, is introduced to obtain the resonant frequency and damping rate of the laser device. This method makes use of the small-signal frequency responses measured at different temperature conditions, and its feasibility has been preliminarily verified. Moreover, the parasitic elements of the laser are analysed with the help of equivalent circuit models. Finally, large-signal measurements are conducted to evaluate the quality of data transmission with the help of eye diagrams. It is worth noting that the impact of temperature on the laser performances is also measured to explore the temperature tolerance of the laser devices.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Due to copyright issues the electronic version of this thesis will not be available for viewing.
Keywords: Resonant tunnelling diode (RTD), distributed feedback (DFB) lasers, high-speed optical/wireless communications.
Subjects: T Technology > T Technology (General)
Colleges/Schools: College of Science and Engineering > School of Engineering
Funder's Name: the European Commission
Supervisor's Name: Kelly, Prof. Anthony
Date of Award: 2020
Embargo Date: 17 June 2023
Depositing User: Mr Weikang Zhang
Unique ID: glathesis:2020-81462
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 18 Jun 2020 06:32
Last Modified: 18 Jun 2020 06:32
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