Monolithic integration of photonic devices for use in a regrowth-free coherent WDM transmitter

In this communication age, consumer internet traffic continues to grow at an exponential rate year on year. As a result, networks need to be continually upgraded to keep up with ever increasing bandwidth demands. Diverse research is currently being undertaken at a global level to produce cost effective solutions to maximize network performance. One such area focuses on the development of photonic integrated circuits (PICs), striving to replicated the same compact design and low power consumption achieved in the electronics industry. However, photonic components are more complex and diverse than their electrical equivalents, such as transistors. As these components can have large footprints, involve multiple electrical contacts and require different material properties for optimal performance, the best approach is not obvious when cost is considered. While platforms such as heterogenous integration and monolithic regrowth have produced PICs with advance functionality, they rely on complex fabrication processes which increase production time and cost. As a result, this thesis proposes a monolithic regrowth-free design for a coherent WDM transmitter which requires less sophisticated fabrication techniques and would therefore be more cost effective to manufacture than alternative methods. The work began with the development of suitable processes for the fabrication of DC and high-speed components associated with the transmitter. Utilizing the associated composite hard mask process, the integration of core components required for the coherent WDM transmitter was undertaken. The monolithic integration of a 1x2 multimode interference coupler, two slotted Fabry-Perot (SFP) lasers, two electroabsorption modulators (EAMs) and a star coupler was demonstrated using regrowth free epitaxy and UV contact lithography. The feasibility of integrating an SFP laser with an EAM by means of injection locking was also investigated, resulting in the production of a 2.5 Gbps eye diagram. It was shown that the high-speed performance of these PICs could be improved by using more advanced modulator designs. As a result, this thesis concludes with an investigation of high speed modulators with the aim of to increase the data rate of the developed PICs. An integratable electroabsorption modulator with a 3 dB bandwidth of 17.5 GHz and a corresponding 12.5 Gbps eye diagram was realized

Using a virtual reality cricket simulator to explore the effects of pressure, competition anxiety on batting performance in cricket

Virtual reality (VR) has created opportunities to innovatively re-imagine the way we examine the relations between pressure, competition anxiety and performance. This study aimed to determine the efficacy of VR as a means of measuring the effects of competition anxiety when pressure manipulations are applied while participants bat in a cricket batting VR simulator. The twenty-eight male participants who took part in two experiments were divided into a high (14, mean age: 22.94, SD: 5.4) and a low skill group (14; mean age: 23.55, SD: 9.9). The aim of the first experiment was to validate the VR simulator as a tool that could capture differences in batting performance between a high and low skilled group. The results showed that high skill participants not only scored significantly higher run rates than low skill participants, but they outperformed the low skill group in all performance measures including higher incidences of correct foot placements that reflect better anticipatory responses. Having established the VR batting simulator as being a reliable tool for capturing batting dynamics, experiment 2 aimed to explore the effects of a pressure manipulation on competition anxiety and batting performance. All measures of competition anxiety were significantly greater for both groups in the high-pressure condition compared to the two low-pressure conditions (p &lt; 0.001). The magnitude of this effect was greater in the low skill group for cognitive (0.59) and somatic (0.794) anxiety. Despite anxiety levels significantly increasing in the high-pressure condition, no significant negative changes to batting performance were found for either group, with both groups actually demonstrating performance improvements. Overall, the findings show how a cricket batting virtual reality simulator can be used as a tool to measure the effects of pressure on competition anxiety and batting performance in tasks involving dynamic skill execution.</p

Regrowth-free single-mode semiconductor laser suitable for monolithic integration based on pits mirror

A regrowth-free single-mode laser that is made using standard UV photolithography is reported. The laser achieves a single-mode side-mode suppression ratio of 37 dB, linewidth of 450 kHz, and tunes across 2.9 nm and is suitable for monolithic integration as a distributed feedback replacement, due to a large free spectral range of 60 nm

Tunable L-band semiconductor laser based on Mach–Zehnder interferometer

A regrowth-free tunable L-band semiconductor laser based on Mach–Zehnder interferometer is presented in this paper. The laser exhibit a side mode suppression ratio of 38 dB and linewidth of 500 kHz. A tuning range of 30 nm across the L-band is also demonstrated

On-chip investigation of phase noise in monolithically integrated gain-switched lasers

Phase noise in gain-switched lasers is investigated theoretically using the semiconductor laser rate equations and compared with the experimental results from monolithically integrated devices. The phase noise of a gain-switched laser is modelled both with and without injection-locking using the rate equations for a single-mode laser. Phase noise is found to increase with gain-switching, and decrease when injection-locked to a master laser. This trend is then observed experimentally on-chip with monolithically integrated devices without the use of an isolator

Deeply etched inner-cavity pit reflector

A deeply etched pit reflector is presented in this paper. The pit is not depth sensitive and has a comparable reflection and loss to a slot. Moreover, a two-section 750 μm laser cavity based on the pits is demonstrated. The laser achieved a side-mode suppression ratio of 40 dB, a linewidth of 280 KHz, and tuning across 40 nm

Single mode semiconductor laser based on coupled cavities of an active ring laser and Fabry Perot

A single mode laser based on coupled cavities of an active ring laser and a Fabry Perot is presented. The laser exhibits tunable single mode behaviour with a side mode suppression ratio of 41 dB and a line-width of 400 kHz

A facetless regrowth-free single mode laser based on MMI couplers

This paper presents a facetless, tunable laser operating near 1575 nm, as well as a theoretical model predicting spectral features of the laser. The lasers were fabricated without regrowth or advanced lithography techniques, and are based on MMI couplers and etched facets. Coarse vernier tuning was achieved over a range of 25 nm, while fine, thermal tuning was also demonstrated over a range of 1.5 nm. SMSR values of 25 dB and higher were observed, with a measured laser linewidth of 600 kHz