Project Type: EngD

Supervisor: Dr Michael Lengden

Project Description

The proposed project will focus on the development of the detection and sensing techniques based on the photothermal effects. It will comprise of the development and characterization of miniature transducers, optical systems enabling this phenomenon as well as the instrumentation required to drive the system. All these aspects of the technology will be explored in the context of applications targeting relevant problems of our customers. As such we believe that this proposed project perfectly fits the scope of this CDT’s programme, in that it is a sensor technology underpinned by photonics technology and will involve a high component of engineering and technology transfer.

The root question we seek to answer over the course of this study is: can established photothermal techniques be enhanced and translated to the spectrally-potent fingerprint region; and if so can the resulting technology be miniaturised and automated such that it can find utility in front line homeland security / environmental monitoring applications? Although the photothermal effects are well established, their use in sensing extra-laboratory applications is still limited. These limitations often come from the size and complexity of relevant system and in this project we aim to drive the development of solutions that can find direct applications in the field. From the design of gas cells and optical systems characterised by superior performance, through the development of measurement techniques simplifying the testing procedure to the miniaturisation and ruggedization of relevant systems, this project will explore ways of marrying exceptional performance with portability and ease of operation.

The project will bring together state of the art developments in Quantum-Cascade excitation lasers operating in the spectroscopically potent 7-12um spectral fingerprint region; low-cost, high-performance 3D-printed acoustic spectrophones and deep-infrared, low-loss optical enhancement cavities. Specifically, this project will merge the know-how and experience in manufacturing of miniature, 3D-printed photoacoustic cells from the Centre for Microsystems and Photonics (CMP) at the University of Strathclyde, and the unique position of Fraunhofer Centre for Applied Photonics in development and application of optical systems. Among other things, the prospective student will explore new molecule excitation schemes, novel cell designs, ways to reduce the noise and calibrate the detector and finally new fields of applications. 

During this project the student will be predominantly based at the premises of Fraunhofer CAP, however thanks to the geographical proximity between the company and the academic group (the same floor of the same building) she/he will enjoy direct access to both teams, enhancing the first-hand exposure for the activities in both teams. The student will be responsible for (a) designing, manufacturing and characterising the miniature acoustic cells; (b) characterising commercial and in-house QCL systems; (c) optical cavity design; (d) instrumentation [optical cavity locking techniques, low-level signal recovery, including digital lock-in amplifiers]. She/he will be responsible for the development of the whole infrastructure of given experiment, data collection and analysis. When appropriate, the student will be involved in commercial projects exploiting the resulting technology.

The photothermal spectroscopic techniques are a very potent and although a single aspect of the above work programme could be considered in a short-term task, in this programme we envisage the student to build up an extensive know-how on principles, implementation and exploitation of this technology. Our vision is for the student to be responsible for a comprehensive overview of the current state of the art, and then a ‘ground up’ design and integration activity to result in an optimised device. It is particularly suited to the engineering Doctorate programme as he/she will be expected to work beyond fundamental bottom-line performance and develop high TRL demonstration modules for exploitation in various gas spectroscopy applications, stand-off photoacoustic sensing and various other concepts based on the photothermal effects. Although from industrial perspective the student may be involved in a portfolio of different projects, the photothermal spectroscopy sits at the core of all the work in this programme which will make for a coherent body of results fully fulfilling the level of doctoral thesis.

CDT Essential Criteria

A Masters level degree (MEng, MPhys, MSc) at 2.1 or equivalent.

Desire to work collegiately, be involved in outreach, undertake taught and professional skills study.

Project Essential Criteria

First- or upper-second degree background in physics, preferably with specialisation in laser physics or acoustics.

Strong ability and desire to set-up experimental systems and put theory into practice.

Ability to work with as part of a wider team and demonstrate initiative when tasked with lone working.

Desire to interact with industrial end-users.

Project Desirable Criteria

Knowledge of programming languages such as Matlab, Labview or Python.

Experience in setting up optical and laser-based systems.

Industrial background and experience in executing commercial projects.