Room Temperature Continuous-Wave Inorganic Maser

Lead Research Organisation: Imperial College London
Department Name: Materials

Abstract

Until very recently the MASER could only be used in very specialist applications such as radio astronomy. The reason for this is that cryogenic cooling and to a lesser extent, high applied magnetic fields, prohibited mass production on the grounds of both complexity and cost. Despite the fact that the MASER was discovered before the LASER these issues meant that the latter, which does not need applied magnetic fields or cooling, saw widespread adoption in a huge range of applications from bar-code readers, laser discs to laser eye surgery.

In 2013 Imperial and UCL were awarded an EPSRC funded research project to produce a room temperature MASER. Although we had preliminary observations that room temperature masing was possible we had not verified this in a different laboratory setting, nor did we have a clear idea of how the masing molecule interacted with light and which crystal orientations or dopant concentrations would be optimal. This collaboration was remarkably successful achieving all the objectives we set.
Now, in what is another world first, the team has constructed a diamond MASER capable of continuous-wave operation at room temperature.

Our previous research has concentrated solely on organic materials as the masing medium. In this proposal we will explore the potential of masing in inorganic materials at room temperature. In doing so we will obviate two key problems encountered with organics.

Problem 1 - Decay rates: The primary obstacle that prevents continuous operation in organics is the relatively long lifetime of the lowest triplet sub-level, reducing the number of pentacenes available for optical pumping (bottleneck) and destroying the population inversion.

Problem 2 - Heating: The organic gain medium, pentacene in p-terphenyl we first used to demonstrate a room temperature MASER cannot withstand a continuous illumination by a laser because the temperature of the terphenyl host rises above its melting point.


Solution to both problems: a radical but exciting departure which will address both problems simultaneously is to explore high spin states in inorganic materials with high melting/decomposition temperature and favourable thermal conductivities (T.C.): such as diamond (M.P. 3550C; T.C. 2000 W/mK) and silicon carbide (2730C; T.C. 120 W/mK).
Very recently we observed masing at room temperature in diamond exploiting NV centres. This means we can build upon a huge wealth of research in the UK and elsewhere on diamond NV centres. Again there is much research exploring defects in SiC that we can build on. We have initiated a collaboration with the group of Prof. Dr. Vladimir Dyakonov at Würzburg group who are currently exploring SiC. REF. https://arxiv.org/pdf/1709.00052.pdf

Achieving this would further establish without doubt the UK as the key place to carry out fundamental research on the topic of room temperature MASERs.

Planned Impact

Who will benefit from this research?

1) There are two demonstrators that we will build to take advantage of the maser's unique properties.
- The most likely early take-up will probably be in very low noise amplifiers and measurements of phase noise. Currently, the noise floor of the best HEMTs is around 22 K at measured 17 K (Bryerton et al DOI:10.1109/MWSYM.2009.5165788). However at room temperature the noise floor of the best InP HEMTS is 0.82dB (60K) (Tsu et al Microelectronic Engineering (2010) doi:10.1016/j.mee.2010.02.012). Estimates of the noise floor of our maser device indicate that it could be very competitive and show that there is plenty of incentive to explore the area of low noise amplifiers.
- Associated with applications that demand a low noise floor are devices that benefit from very low phase noise. We have plans to build two devices so that we can measure the phase noise.
2) Magnetic Resonance Imaging / Nuclear Magnetic Resonance and Electron Paramagnetic Resonance - all three would benefit from better LNAs.
3) Flowing on from its potential as an extremely sensitive sensor one can imagine miniaturisation to devices capable of medical diagnostics. Indeed the current LCR) inductance, capacitance, resistance) circuit is only a millimetre in size.
4) Quantum computing. Given that the fundamental process occurring in a maser is the conversion of optical photons to coherent microwave photons, we expect the field of diamond-based quantum optics to be an immediate beneficiary of this work, where the optical-microwave photon interface is key to the initialization, manipulation and detection of quantum states.

A caveat must be noted. It took us 5 years to move from a pulsed MASER to a continuous-wave MASER and the average time taken from discovery to serious commercialisation is anywhere between 10-30 years. In preparation however, IC and UCL are taking care to protect intellectual property with one patent granted, and four filed. The protection of intellectual property is being handled by Imperial Innovations and by UCL Enterprise. We already have collaboration agreements in place.

How will they benefit from the research?
It is really too early to make definitive statements as to where the research will lead and who will benefit, but to generalise:

- the maser is expected to impact in the area of healthcare because of improved signal to noise sensors for magnetic resonance in particular.
- In the area of communications again because of improved signal to noise ratio and because of potential for very low phase noise. In the proposal we will explore the phase noise of the system.
- possibly in the area of room temperature quantum computing although this has some way to go.

We will take advice from an Industrial Partner board which will be made up from our industrial partners as well as Imperial Innovations, UCL enterprise and the principal investigators. The main objective of the board will be to focus on the impact of the research by taking a broader and more commercial view of the science and engineering. As mentioned in the case for support we will target low noise amplifiers and very low phase noise as the initial demonstrators.
 
Description The acronym Maser stands for "microwave amplification by stimulated emission of radiation", and the physics behind the maser is essentially the same as that of the laser (light amplification by stimulated emission of radiation): both produce electromagnetic radiation at a single wavelength/frequency. One of the main current uses of masers is for deep space communication, due to their ability to amplify tiny signals, e.g. from probes such as the Voyager Spacecraft, without adding noise to the signal. Thus, they also have the potential to be useful for future communication technologies on which our world increasingly depends.

However, unlike lasers, which were realized after the maser, and have become ubiquitous technologies, most masers work under inconvenient conditions, such as very low temperatures that require liquid helium for cooling. In contrast the maser presented in this paper works at ambient conditions, and makes use of a sapphire microwave resonator held in a magnet to contain and concentrate the microwaves produced following optical excitation of Nitrogen-Vacancy (NV) Centres in the diamond. In contrast to pure diamonds which only contain carbon atoms and therefore are colorless, in the diamond used in this study, a small number of carbon atoms are replaced by nitrogen atom, and a site next to the nitrogen atom, which would normally contain a carbon atom is empty. Hence, this defect is known as an NV Centre.

Diamonds containing NV Centres have a myriad of remarkable quantum properties that make them the subject of a huge research effort in order to develop novel technologies, particularly for sensing at the nanoscale - often referred to as nanometrology.


Given that masers use optical photons to create microwave photons, it is expected that this demonstration will open up a new avenues in the field of diamond quantum technology, including in quantum computing, quantum communication, quantum optics and quantum sensing.


The work was supported by the UK Engineering and Physical Sciences Research Council through grants EP/K011987/1 (IC) and EP/K011804/1 (UCL) and the Henry Royce Institute.
Exploitation Route Potential applications:

Low noise amplifiers
ESR Imaging
Ultra low phase noise applications
Deep space comms
Satellite comms
Telecomms
Quantum computing
Quantum sensing
Sectors Aerospace

Defence and Marine

Digital/Communication/Information Technologies (including Software)

Electronics

Healthcare

Security and Diplomacy

 
Description New collaborations with 2 industrial partners
First Year Of Impact 2019
 
Description Nanoscale Advanced Materials Engineering
Amount £7,671,801 (GBP)
Funding ID EP/V001914/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 06/2021 
End 06/2026
 
Description Room Temperature, Earth's Field MASER
Amount £1,200,284 (GBP)
Funding ID EP/K011987/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 01/2013 
End 08/2017
 
Description University of Manchester 
Organisation University of Manchester
Country United Kingdom 
Sector Academic/University 
PI Contribution Collaboration on a Programme Grant
Collaborator Contribution Scientific research
Impact No outputs yet
Start Year 2017
 
Description collaboration with Leeds University 
Organisation University of Leeds
Country United Kingdom 
Sector Academic/University 
PI Contribution Collaboration within Royce and a new Programme Grant
Collaborator Contribution Scientific research
Impact Multidisciplinary Physics, Materials, Chemistry, Electrical engineering
Start Year 2017
 
Title A Light Source 
Description There is provided a light source arranged to output light at a first wavelength. The light source comprises a luminescent concentrator having a slab-shaped geometry. The luminescent concentrator comprises: an input port arranged to receive light and define a first area; an output port arranged to transmit light and define a second area which is smaller than the first area; and surfaces arranged to direct light inside the luminescent concentrator to the output port. The luminescent concentrator further comprises lumophores arranged to receive light at a second wavelength and emit light at the first wavelength; and a pump light supply coupled to the input port and arranged to illuminate the input port with light at the second wavelength. 
IP Reference US2017329065 
Protection Patent application published
Year Protection Granted 2017
Licensed No
Impact In progress
 
Title DEVICE AND METHOD FOR GENERATING STIMULATED EMISSION OF MICROWAVE OR RADIO FREQUENCY RADIATION 
Description A device for generating stimulated emission of microwave or radio frequency electromagnetic radiation, the device comprising: a resonator structure;an input source of microwave or radio frequency electromagnetic radiation to be amplified; and an input of energy arranged to pump the resonator structure and thereby cause amplification of the electromagnetic radiation; wherein the configuration of the resonator structure and/or the materials used in its construction give rise to an increase in the magnetic Purcell factor of the resonator structure. Corresponding methods for generating stimulated emission of microwave or radio frequency electromagnetic radiation are also provided. 
IP Reference WO2013175235 
Protection Patent granted
Year Protection Granted 2013
Licensed No
Impact . These breakthroughs have received significant global attention; the room temperature maser was recognised as one of the top 10 breakthroughs in 2012 by Physics World, celebrated for the UK Engineering and Physical Sciences Research Council (EPSRC) 20th Anniversary in 2014, presented to an international audience at the World Economic Forum by Professor Neil Alford in 2016 and exhibited at the Royal Society Summer Exhibition in 2017. (https://royalsociety.org/science-events-and-lectures/2017/sum
 
Title ROOM TEMPERATURE MASING USING SPIN-DEFECT CENTRES 
Description Apparatus for achieving masing at room temperature, the apparatus comprising: a microwave cavity which exhibits a resonance of sufficiently high Q-factor for maser oscillation; a resonator structure comprising a masing medium located within a resonant element, wherein the masing medium comprises spin-defect centres, the resonator structure being disposed within the microwave cavity; means for applying a magnetic field across the masing medium; an input of microwave radiation to be amplified, the input of microwave radiation being coupled to the resonator structure; and means for optically pumping the masing medium and thereby causing stimulated emission of microwave photons; wherein the microwave cavity has an effective magnetic mode volume matching the volume of the masing medium. A corresponding method for producing masing at room temperature is also provided. 
IP Reference WO2019021002 
Protection Patent application published
Year Protection Granted 2019
Licensed No
Impact in progress
 
Description 51st International Meeting of the Royal Society of Chemistry ESR Group - Dr Jon Breeze invited talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The ESR Group was founded in 1968 as a forum within the Chemical Society for scientists to share, disseminate and promote knowledge about electron spin resonance. The main aim of the RSC ESR Group is to promote innovation, share and advance knowledge, and to encourage applications of electron spin resonance in chemistry, as well as in physical and biological sciences and their applications.
Year(s) Of Engagement Activity 2018
URL https://www.rsc.org/events/detail/30647/51st-annual-international-meeting-of-the-esr-spectroscopy-gr...
 
Description Google SciFoo Dr Jon Breeze invitation to participate 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact From its inception in 2006, Sci Foo has always been hosted at Google's famed headquarters: the Googleplex. However, for this year's event, a larger Google venue - the secretive "X" (formerly "Google X") - played host to more than 300 attendees, who made up the largest invite list in Sci Foo's history. The halls of X, home of many ambitious "moonshots" like self-driving cars and Internet balloons, served as an inspiring backdrop for Sci Foo attendees.

Sci Foo is not your traditional scientific conference. The schedule, which is sprinkled with keynotes, lightning talks, and meal times, is otherwise open to be filled up with "unconference" sessions that the attendees themselves organize and run. Attendees are free to rove from session-to-session, and choose whichever ones grab their curiosity. Unconference sessions are by their nature unconstrained and may take the form of discussions, debates, or lectures. But the most successful and exciting sessions are always the ones that demand interactivity, and active participation from attendees of diverse backgrounds.
Year(s) Of Engagement Activity 2018
URL https://www.digital-science.com/blog/guest/sci-foo-2018-changing-the-world-one-weekend-at-a-time/
 
Description International Conference on Materials for Advanced Technologies - Dr Jon Breeze invited talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The first 9 conferences in this biennial ICMAT series attracted more than 23,000 participants including 25 Nobel Laureates and hundreds of distinguished plenary & keynote speakers, in addition to thousands of invited speakers

The 10th conference had 45 technical symposia, 10 plenary lectures and several theme, keynote, invited, oral and poster presentations with the participation of 3,500 delegates internationally.

One of the largely participated conferences of its kind, each and every edition of this conference series remained as a premier scientific platform for both local and international materials scientists, engineers and technologists to share their expertise and knowledge.
Year(s) Of Engagement Activity 2019
URL http://icmat2019.mrs.org.sg/
 
Description Materials Research Society Boston Dr Jon Breeze invited talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact General dissemination of research
Year(s) Of Engagement Activity 2019
URL https://www.mrs.org/fall2019
 
Description Royal Society Summer Exhibition 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Schools
Results and Impact RSSE data

Students* Teachers Public Subtotal (public, schools and media)
2002 262 10,123 12,438 1,224 13,611


What is a MASER? We've all heard of LASERs - the acronym stands for Light Amplification by Stimulated Emission of Radiation - that provide intense beams of light and represent a several billion-dollar industry. We use them everywhere from supermarket checkouts to CD players and eye surgery. But before the LASER, there was the MASER, where instead of visible light, microwaves were amplified. SoL for light and M for microwave The main difference is the frequency - our maser works at roughly the same frequency as your mobile phone 1.5 GHz.
What are they used for? Microwaves are used in communications, e.g. mobile phones and satellite networks and are good at getting information from A to B, even in challenging circumstances. And it doesn't get much more challenging than space. Yet with microwave technology, we can send images 225 million kilometers from Mars to Earth. We do this using MASERs, which take extremely weak signals and amplify them without adding noise.
What is the key advantage? It's all to do with signal to noise. Noise is the bane of electronic engineers. We see it on our TVs and hear it on our mobile phones and our radios. A maser can amplify the signal we want without adding noise. The images that were sent from the Rover on mars are transmitted using microwaves. These are picked up on Earth using a conventional maser that amplifies the miniscule signal (it's Attowatts 10-18 of a Watt) so that we can see the amazing images of Mars.
What's the big deal with your MASER?. The traditional masers need a magnetic field and need to be kept at cryogenic temperatures so they are bulky, costly and just too difficult - no prospect at all of mass production. Our maser doesn't need cooling and doesn't need a magnetic field and that means it can be miniaturised and mass produced.
What will it be used for? If we can amplify tiny signals and increase signal to noise then we can use them as very low noise amplifiers - these are found in all manner of electronic equipment but our noise floor is 2-3 orders of magnitude lower than the best semiconductor (high electron mobility transistors) available today. So for example we would get better images in a MRI machine or clearer communications. Already we can foresee additional applications for the re-engineered maser that include more sensitive medical scanners; chemical sensors for remotely detecting explosives; advanced quantum computer components; and better radio astronomy devices for potentially detecting life on other planets.
Year(s) Of Engagement Activity 2017
URL https://royalsociety.org/science-events-and-lectures/2017/summer-science-exhibition/exhibits/amazing...
 
Description YouTube Video "The maser goes mainstream", produced by Nature with 160,000+ views 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Considerable press interest/radio interviews
Year(s) Of Engagement Activity 2018
URL https://www.nature.com/articles/d41586-018-07890-0