Type                ~80% Experimental, ~20% Numerical

Description.    The elegant Nobel Prize winning Chirped Pulse Amplification (CPA) technique allows us to overcome damaging non-linear processes such as the Kerr effect that might otherwise destroy a high-power laser as soon as it is turned on.  In CPA short (ps to fs) pulses of light are stretched in time, amplified and then recompressed to deliver peak powers well in excess of 1 Terawatt (10E12 W).  Since its invention, CPA has been extended in many ways to enable a revolution in the capability of both “small” table sized lasers and very large “national facility” machines and their ability to drive and probe a huge range of experiments and applications in areas as diverse as attosecond science, molecular dynamics, biological imaging and inertial fusion.

The UK national lab AWE Aldermaston operates the large ~£200M Orion laser system, which incorporates two World Class petawatt (~1ps, 1kJ) beams that are used to drive both their in-house experiments and also academic access for undertaken by the wider UK scientific community.  Orion is now due for a major upgrade, and this PhD project will act as a test bed for new laser techniques that may be incorporated (at much larger scale and cost) in Orion.  A key part of this is to investigate ways to use non-linear optical processes to efficiently wavelength shift Orion laser pulses from the infra-red to visible green.  This is an inherently “lossy” process, but has the key advantage that it can remove unwanted optical “noise” that might otherwise destroy a target or radically change the physics the laser drives.

The project will be based on the Cerberus laser at Imperial College.  This multi-TW OPCPA system uses similar pulse stretching and non-linear optical parametric amplifiers as Orion, which allows it to act as a highly effective test bed for new laser techniques.  The PhD research will explore ways to efficiently frequency double sub ps IR laser pulses, and mitigate against optical damage, while at the same time enhancing their “contrast”, the ratio of the peak of the laser pulse to unwanted optical “noise”.  It will be primarily experimental and includes the development of new state of the art laser measurement systems.  Some supporting numerical work will also be undertaken to develop and benchmark models of the optical parametric (OPCPA) and frequency doubling processes with “chirped” or spectrally shaped light pulses to improve overall laser efficiency.

Funding   
UK Nationality Required.  Expected to be funded by a UK national lab covering fees and bursary at the level of a standard EPSRC PhD studentship award, plus travel, lab consumables and some items of equipment.  AWE Aldermaston have identified this project as a priority for their internal funding process in support of an upgrade to the large Orion laser.  We expect to hear about the status of this bid in early January 2023.