Novel quasi phase matching of high harmonic generation via advanced dual gas multi jet targets

Lead Research Organisation: Queen's University of Belfast
Department Name: Sch of Mathematics and Physics


Ultrafast/attosecond physics is an exciting and dynamic research discipline, revealing atomic and molecular structures/processes with unprecedented spatial and temporal resolution. A significant limitation, however, has been the limited amount of laser energy that can be converted into XUV and soft x-ray regions of the spectrum. This is primarily due to phase mismatch between the driving laser and generated harmonic field, induced by the large free-electron contribution to the refractive index. Quasi-phasematching has been a front runner in the drive towards this objective but to date has been largely confined to low average power 'proof-of-principle' experiments in hollow core capillaries. This proposal seeks to develop a ground breaking new approach to quasi-phasematching developed by our group at QUB - dual gas multi-jet arrays in a capillary free geometry - to an exceptionally high standard.

In this proposal we intend to build upon experimental observations already made which verify this exciting new technique. Together with our collaborators at the HASYLAB (DESY, Hamburg) and TEI Rethymno (Crete) the current design will be extended to generate a high average power harmonic source suitable for seeding the FLASH free electron laser at DESY. In a second strand of this proposal we will use the unique ability of this source to fine-control the phase of HHG emission for intense single attosecond pulse generation. This proposal will form the core of an international collaboration aimed at delivering the first high average power HHG source and intense attosecond pulses, and work will be performed on lasers at QUB, DESY and TEI Crete.

Planned Impact

The socio-economic impact of developing complete coherent control of high harmonic generation in gases can be categorized into two main strands.

First to benefit will be the accelerator based ultrafast X-ray source user community - including groups from both science and industry. This community spans materials science (semiconductor industry, advanced materials for solar cell research etc) to diffractive imaging of single molecules for in vivo studies of biomedical samples. Our research will allow better pulse energy stability and focusability of the X-ray radiation produced by these multi billion pound machines, which in turn will allow users to metrologise their samples with unprecedented accuracy.

Secondly, over a longer term, this work will contribute significantly to the downsizing of ultrafast X-ray sources. Controlling the process by which harmonics are generated in gas targets coherently will ultimately lead to compact bright sources. In turn this will provide the basis for moderately priced systems (<£3m) that will be useful in numerous scientific and industrial applications. One excellent example of this is imaging of in vivo cells in aqueous solutions using coherent radiation generated in the 'water-window' region of the spectrum. Allowing onoclogical researchers access to systems capable of delivering bright water window radiation on a regular basis from an in house system (as opposed to competitive slots at large facilities) will expedite our understanding of the basic mechanisms of metastasis and hopefully, in time, lead to better cures/preventative measures for the spread of cancer in the body. Our method for coherent control of the generation process of X-rays in gases is the first step on the road to such a commercially viable device.
Description Develping novel gas targets for short pulses of x-rays to study atomic processes
Exploitation Route Our findings can be implemented as seed sources for next generation high average power x-ray free electron lasers
Sectors Aerospace, Defence and Marine,Education,Electronics,Environment,Security and Diplomacy,Other

Description We have applied our findings to the generation of new sources for biomedical imaging and materials science. We have submitted our finds to scientific journals for publication (Review of scientific instruments and New journal of physics. This has led to the development of novel targets and new methods to enhance the efficiency of attosecond pulse generation
First Year Of Impact 2012
Sector Aerospace, Defence and Marine,Education,Electronics,Energy,Security and Diplomacy,Transport,Other
Impact Types Societal,Economic

Description EPSRC equipment upgrade
Amount £1,000,000 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 05/2015 
End 10/2016
Description Helmholtz institute Jena 
Organisation Friedrich Schiller University Jena (FSU)
Country Germany 
Sector Academic/University 
PI Contribution WE attended and designed new experiments on the Jeti laser in Jena
Collaborator Contribution Access to world class laser facilities, plasma mirror setup and cutting edge diagnostic suite
Impact > 6 published articles (PRL, 3 invited talks at international conferences
Start Year 2010
Description Partnership with Class 5 lasers DESY hamburg 
Organisation Deutsches Electronen-Synchrotron (DESY)
Country Germany 
Sector Academic/University 
PI Contribution We have aided in developing novel x-ray sources for deployment at free electron lasers
Collaborator Contribution They have provided access to expertise and engineering
Impact 3 publications accepted, two publications pending
Start Year 2012
Description TEI Crete collaboration 
Organisation Technological Educational Institute of Crete
Country Greece 
Sector Academic/University 
PI Contribution Travelled and performed experiments at the ultrafast laser system in Rethymno, Crete
Collaborator Contribution They provided access to their laser system at not cost and full time experimental support
Impact 3 publications, 1 PRL, 1 New Journal of Physics and 1 Optics letters Plans and invitations for future experiments
Start Year 2010
Description Crete summer school 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Creating awareness to international PhD students about on going work in relativistic laser plasmas and attosecond sources

Experiments planned, international networking, invited talks
Year(s) Of Engagement Activity 2009,2010,2011,2012,2013,2014
Description Cross border schools initiative 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Schools
Results and Impact School students interest in scientific discussions

Students planning to visit lab, cross border initiative
Year(s) Of Engagement Activity 2012,2013,2014
Description Incredible power of light roadshow 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact We hosted and provided full time staffing for the Incredible power of light roadshow from the STFC in the Ulster Museum during February and March 2015. Our active participation in this public out reach event saw over 10,000 members of the public and over 1000 pupils from regional (Northern Ireland) schools. We demonstrated the exhibits and informed attendees about how to pursue careers in science, technology engineering and mathematics with particular emphasis on laser and light based technologies. Since this was the first year it was difficult to directly measure impact. However our success saw my group invited to return to present the exhibits again the following year (2016).

Also the impact on regional schools was tangible with over 10 requests from individual school groups to provide year round displays in public forums with dedicated exhibitors such as those provided by my group.
Year(s) Of Engagement Activity 2015
Description Lasers live demonstration, Northern Ireland Science festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact In 2015 the inaugural Northern Ireland Science festival was held. Following our successful collaboration with Ulster museum with the STFCs Incredible Power of Light roadshow we were invited to build and demonstrate a Laser's Live exhibition in the Foyer of the Ulster Museum. This highly visible location saw nearly 11,000 members of the public attend live demonstrations of how light energy can be harnessed over an 9 day period in 2015.

This was so successful the Ulster Museum invited us to return for an extended period in 2016, extending our reach beyond that of the Northern Ireland Science festival for a 12 day residence in the Foyer. This saw > 18,000 attendees to the museum visit our live demonstrations

We performed detailed metrology in 2016 with over 1000 questionnaires completed by school students and members of the public with ages ranging from 3 - >60 years. The results of these questionnaires are currently being processed but the response has been overwhelming.

All numbers for attendance are official numbers of the Ulster Museum.
Year(s) Of Engagement Activity 2015,2016
Description UCD Japan Ireland Initiative 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Generate new collaborative links in Japan, investigate novel funding streams

New collaborations forged, invitations to international labs for experiments
Year(s) Of Engagement Activity 2012,2013,2014