This thesis describes the design, development, testing and evaluation of instrumentation designed to work with and enable the performance of spin-exchange relaxation-free magnetometers. The instrumentation includes ultra-low noise bi-polar current sources for driving magnetic field nulling coils and exhibiting ≈ 15 ppb/√ Hz wideband noise and narrow 1/f noise bandwidth of 1 Hz. Custom photodetectors featuring very low noise of ≈ 52 nV/√ Hz after 100 Hz for transimpedance gain of 150 kV/A were designed, built, and characterised. The detector also features adjustable gain and bandwidth, with the ability to accept a range of photodiodes to suit different applications. A custom laser driver for driving vertical-cavity surface-emitting (VCSELs) lasers was also developed, featuring very low current noise of 40 pA/√ Hz at 10 Hz and diode temperature controller capable of stabilising the temperature to < 0.5 mK. The thesis also describes the development of two, spin-exchange relaxation-free magnetometers. One utilising 87Rb, which is a lab-based experiment and a portable sensor that uses 133Cs as its alkali species. Both experiments benefit from custom instrumentation developed, achieving ultimate sensitivity of 24.7 fT/√ Hz and 90 fT/ √ Hz respectively. Additionally, the thesis describes an investigation of low-power and low-intensity noise vertical-cavity surface-emitting lasers as an alternative coherent light source to distributed Bragg reflector lasers commonly used for optically pumped magnetometers. The change to inexpensive and power-efficient laser light sources offers a benefit for the development of portable magnetometers.
| Date of Award | 9 Jan 2024 |
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| Original language | English |
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| Awarding Institution | - University Of Strathclyde
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| Sponsors | EPSRC (Engineering and Physical Sciences Research Council) |
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| Supervisor | Paul Griffin (Supervisor) & Erling Riis (Supervisor) |
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