PhD opportunities

The Chimera high-power mid-IR OPCPA laser system.

Title: The Chimera high-power mid-IR OPCPA laser system.

Type: Experimental 80%, computational 20%

Funding: EPSRC DTA with DSTL top-up (UK nationality required).

Supervisors: Dr Stuart Mangles and Professor Roland Smith

Description: We are developing a new and unique type of mid infrared laser system based on "Optical Parametric Chirped Pulse Amplification" (OPCPA) as part of a large UK-US collaboration funded by DSTL, EPSRC and the US AFOSR.  CPA is an elegant temporal stretch-compression technique that allows short pulses to be amplified to high energy without destroying the laser system, while optical parametric amplification (OPA) involves instantaneous transfer of energy from one laser beam to another.  OPA has the advantage of very high gain, low noise and huge bandwidth compared to "traditional" laser amplifiers.  It also allows access to laser wavelengths from 2-10 microns where it is very difficult to find a "traditional" laser material.

Our new Chimera laser combines the CPA and OPA techniques and will deliver multiple ultra-short light pulses to experiments including laser particle acceleration systems.  Here moving to longer wavelengths offers some very attractive benefits as there is a strong l2 scaling of the energy an electron can acquire from the light field.  The PhD will involve a combination of innovative laser development, characterisation of ultra-short light pulses (including the development of new instruments) and use of mid-IR light pulses in experiments.  Laser acceleration work will likely include campaigns at both Imperial and at some of our US collaborators laboratories.

Ultra-high contrast multi-terawatt laser systems.

Title: Ultra-high contrast multi-terawatt laser systems.
Type: Experimental 80%, computational 20%
Funding: EPSRC industrial CASE with AWE (UK nationality required).  We are now recruiting for a student to start in October 2018.  
Supervisor: Professor Roland Smith
Description:  Current generation short-pulse, high-power laser systems can deliver peak powers in the terawatt (1012W) to petawatt (1015W) range and are used to probe and drive a very broad range of exotic processes including laser particle acceleration and laboratory simulations of supernova explosions and astrophysical jet formation.  These lasers use a technique called Chirped Pulse Amplification (CPA) to stretch, amplify and compress a light pulse in time to avoid destroying the system.  However this temporal manipulation also introduces subtle and unwanted effects that result in "low power" light a million or more times or less bright than the "main" pulse arriving on target early in time.  This can cause catastrophic changes to experiments, for example destroying a fragile target before the "real" experiment can begin.
This project will identify sources of optical scatter, optical noise and temporal distortion in large CPA laser systems (particularly from diffraction gratings), characterise laser pre-pulse over ~11 orders of magnitude in intensity, and develop new methods of reducing pre-pulse.  Experimental work will be based around "Cerberus" at Imperial, the UK's largest University based laser system.  Cerberus is used for both development and testing of advanced laser concepts, and drives a broad range of experimental plasma physics campaigns.  These include both stand-alone laser-plasma interaction and X-ray generation experiments and work in conjunction with the world's largest open access Z-Pinch MAGPIE.  Cerberus is a "hybrid" multi-beam system that utilises large aperture flashlamp pumped Nd:Glass based power amplifiers.  To extract the best performance from these very powerful amplifiers we couple them to an advanced "optical parametric chirped pulse amplification" (OPCPA) front end.
The project will involve collaborations with laser physicists from the UK's major National Facilities, the Rutherford Appleton laboratory and AWE Aldermaston.  Working as a multi-institute consortium we will have a much more leverage when persuading major grating manufacturers to create new and unique types of low-scatter optics.