Industry / Innovation

Potential impact

The device concept developed within TREASURE will open new perspectives for various THz technological applications, mainly due to the compact and rugged form of the device, to its low-power consumption, and to its room-temperature operation. The expected level of performances is unprecedented both in and outside Europe. Moreover the device is scalable, in the sense that the elementary emission units of the device can be multiplied and integrated, thus forming THz emitter arrays. This opens the possibility of adjusting the total emitted power and creating a flexible platform to address poorly solved problems, such as THz bio-chemical sensing and THz imagery.

To recapitulate, the TREASURE project will deliver a device, electrically pumped at room temperature, which generates a high intensity of spectrally pure THz radiation. The TREASURE technology will form a platform that will allow further development of both the technology itself and the applications based on this technology, beyond the duration of the project.

Further development of the TREASURE technology may allow phase-locking of several THz emitters, enabling coherent addition of the outputs of an array of N emitters with an even higher output power (Iout~N2) as well as the possibility of steerable beams from phased arrays. A room-temperature, electrically pumped light source with such properties will have profound impact on the technological development of our society, as detailed below.

Market reports predict that in 10 years, the worldwide market for THz technology will increase from its current annual volume of approximately 10-30 million dollars [60,61] to approximately 500 million dollars [61,62]. This increase will be driven by emerging applications of THz technology, including security and screening applications, biomedical applications, non-destructive evaluation and testing applications, and THz wireless communication technology. The successful TREASURE project will have a significant and positive impact on all these applications, and will lead to a further increase of the volume of the market for THz technology.

As a specific example of the impact of the TREASURE device, consider its use as replacement of the current state-of-the-art for generation of frequencies above 1 THz, namely photo-mixing of two laser lines with a frequency difference corresponding to the generated THz frequency. Despite the fact that photo-mixer transceivers have been developed for more than one decade, the power levels available from such devices remain rather low, especially at high frequencies. For instance, in the 2-3 THz band maximum output powers are of only a few nW [63]. Such low power levels are among the main factors limiting the bandwidth of photoconductive transceivers. Note that merely increasing the power of the laser diode pumps is not a solution to this problem since beyond ~50mW pump, photo-mixers suffer from permanent thermal damage [64].

Thus the TREASURE device offers the exciting and commercially attractive possibility of replacing a system consisting of two laser sources, optical feeds, power supplies, and photo-mixing circuit, with a single integrated, electrically pumped component, capable of generating orders of magnitude higher THz intensity at the interesting frequency band above 2.5 THz.

The following table compares the TREASURE device with photo-mixer technology:

TREASURE device Photo-mixer
Material Standard III-V MBE growth Low-temperature III-V MBE growth
Frequency range 2.5-6 THz 0.05-2 THz
THz power > µW at all frequencies ~µW at 0.1 THz, nW at 2 THz
Pump DC current Two CW lasers
Tunability By design of MR structure By tuning of laser emission frequencies
Scalable Yes, can be integrated into arrays Difficult due to parallel optical excitation
Use as detector Yes, electrically driven                 upconversion (Idet µITHz) Yes, requires optically driven homodyning (Idet µ ETHz)
Phase-locked     operation Potentially, must be developed Potentially, requires phase-locked, parallel excitation with single laser source

An important example of the applications that will be enabled by the TREASURE technology is the detection of trace gases. From an environmental point of view, an important application of gas phase spectroscopy at THz frequencies is given by the study of chemical processes in the upper atmosphere, which are important in ozone formation and destruction. Indeed, many atmospheric molecules have strong absorption bands in the far IR e.g. water, oxygen, carbon monoxide, the hydroxyl radical, and nitrogen to name a few.

For instance the hydroxyl radical (OH) in the stratosphere is an important player in known ozone depletion cycles, and is also a critical element for the formation of photochemical smog. OH is also critical in many combustion based industrial processes. For instance the temperature profile of a flame can be obtained from the concentration of OH [65]. For all these reasons the quantification of this gas phase radical is a key objective for various fields of applied and fundamental research and in particular for environmental monitoring. Other than in the UV, which suffers from interference from nearby SO2 and C10H8 transitions, the strongest absorption lines of OH are located around 2.5 THz (2.510 THz and 2.514 THz) and are suitable for its detection at low concentrations. Frequencies around 2.5 THz are particularly well suited for atmospheric monitoring. In fact this frequency band is located in a relatively transparent window of the atmosphere, with the closest significant water transition found approximately 50 GHz away from OH absorption lines. Unlike the infrared and UV domains, THz radiation offers the advantage of being insensitive to scattering caused by the presence of aerosols or particulate matter, allowing studies of industrial emissions and flames to be undertaken. THz spectroscopy is thus an excellent solution for the measurement of OH at low concentrations and under various conditions including flames and industrial emissions such as smoke.

In this context, the TREASURE coherent generation and detection technology will have major impact on the feasibility of future gas detection systems based on far-infrared spectroscopy.

The TREASURE technology is scalable to arrays. This directly opens up the possibility of using this technology for future focal-plane imaging. Although certain mid-IR focal-plane imaging systems are capable of detecting THz radiation at sufficiently high intensity, no focal-plane imaging systems are currently optimised for high sensitivity in the THz range. Thus the TREASURE technology, being inherently frequency-selective, offers completely new imaging capabilities including chemical specificity, hyper-spectral imaging, and high suppression of thermal background radiation in the 2.5-6 THz region.

Finally, and independently of the impact on THz technology detailed above, we would like to stress the additional scientific impact of TREASURE project: on WGM physics (Q factors well beyond 105 are promised by optimised etching and passivation), QD lasers (high power WGM lasing at room temperature), and accurate refractive index models in the THz range.

Contribution at the EU level

The expected impacts listed in the work programme in relation to our topic are:

  1. Leading position of European industry in high-value photonic products.
  2. New photonic-based applications in several industrial sectors with emphasis on communications, health, well being, environment, safety and security.
  3. Continued European leadership in RTD in photonics from components to systems, securing the necessary human resources and knowledge to design, produce and use new generations of photonic components.

Each of these issues is referred to by one or more central points of this project.

Industrial interest

There is a strong interest for European industry in the development of cheap, compact and easy-to-use THz sources. Terahertz technology is now at a point where it has serious potential in the commercial domain. THz biomedical applications, still in its infancy, promise wide margins for European industry to fill the historical gap accumulated with respect to Japanese and American competitors.

AL will leverage on its existing customer base in the THz field as well as its contacts in this domain, to provide an accelerated route to the market of THz integrators. AL will advertise the potential of the technology in order to attract early adopters and thus obtain early recognition of a wider range of specialists applying the technology as a mean to satisfy their needs. This will firstly establish a solvable need and secondly attract additional funding for developing new applications of the TREASURE source.

The development of very compact (and precisely localized) THz sources can open the route towards optical distribution of THz local oscillators very close to THz detectors. In other words it would permit optical distribution of the necessary local oscillators to all the pixel of a THz camera operating in the coherent detection mode. Such a coherent camera is of primary importance because it would permit a practical use of THz imaging, e.g. for people screening at few meter distance.

European dimension

This proposal brings together three of the leading groups in semiconductor photonics and THz sources (CEA, UPD, AL), a major actor in semiconductor technology (UW) and a leader of THz applications (DTU). On the one hand, no national consortium could provide such a high-level convergence of different cultures and technologies toward such an interdisciplinary and application-oriented goal in THz integrated photonics. On the other hand, teamwork efficiency is granted by the strong scientific links already established within the consortium, as illustrated in Section B.2.3.

Project-related patents

J. Claudon et al., French Patent 08 53939 (CEA and Paris Diderot University, 13/06/2008).

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Hired people

A PhD student is partially funded by the TREASURE project:
- Silvia Mariani

Also funded by TREASURE project is the Project Manager at Paris Diderot University:
- Anne-Sophie Refloc'h

A post doc is being funded by the TREASURE project at Julius-Maximilians Universitaet Wuerzburg:
- Fabian Langer

Conferences

The TREASURE consortium organises:
a workshop session dedicated to electrically-injected nonlinear THz emitters at 300K, within the 7th Terahertz days and GDR-I workshop to be held in Cargèse, Corsica, France, 25-27 March 2013

The TREASURE consortium attended:

7th Optoelectronics & Photonics School, 16-22 March 2013, Trento, Italy

NLO 50 International Symposium, 8-10 October 2012, Barcelona, Spain, "AlGaAs micropillars for THz DFG"

IEEE International Semiconductor Laser Conference San Diego, USA, 7-10 October 2012, "Room Temperature, Continuous Wave Lasing in Microcylinder and Microring Quantum Dot Laser Diodes"

Nonlinear Optics, 17-21 June 2012, Colorado Springs (Colorado), United States, "Optical Characterization of Nonlinear THz Emitters"

3rd EOS Topical Meeting on Terahertz Science & Technology (TST 2012), 17 -20 June, 2012 Prague, Czech Republic (Poster Presentation)

Industrial Exhibits

The TREASURE consortium attended:

International Quantum Cascade Lasers School & Workshop 2012, September 2-6, 2012, Baden bei Wien, Austria.

Future Security, Security Research Conference, September 4 – 6, 2012, Bonn, Germany.

Pittcon 2012, Orlando, FL from 11 March to 15 March 2012. Major new products and technologies in the field of analytical and laboratory instruments.

Laser Applications to Chemical Security and Environmental (LACSEA), 29 January - 1 February 2012, Rancho Bernardo Inn, San Diego, California, United States

SPIE Defense Security & Sensing, "International Defense, Security & Sensing Exhibition", April 23-27 2012, Baltimore, United States

Swiss NanoConvention 2012, “the prime showcase for nanotechnology in Switzerland”, Lausanne May 23rd 2012, Lausanne, Switzerland

FLAIR 2011 - Field Laser Applications in Industry and Research / September 13-17, 2011, Conference Center, Murnau, Germany

10e Rencontres HélioSpir, September 24, 2011, Montpellier, France

LASER World of PHOTONICS, May 23-26, 2011 Munich, Germany

"Alliance" organization was visited in order to prepare a technology offer on the "Enterprise Europe Network"